Mushrooms—fleshy fungi—are the premier recyclers on the planet. Fungi are essential to recycling organic wastes and the efficient return of nutrients back into the ecosystem. Not only are they recognized for their importance within the environment, but also for their effect on human evolution and health. Yet, to date, the inherent biological power embodied within the mycelial network of mushrooms largely remains a vast, untapped resource. As we begin the twenty-first century, ecologists, foresters, bioremediators, pharmacologists, and mushroom growers are converging at a new frontier of knowledge, wherein enormous biodynamic forces are at play.

Only recently have we learned enough about the cultivation of mushrooms to tap into their inherent biological power. Working with mushroom mycelium en masse will empower every country, farm, recycling center, and individual with direct economic, ecological, and medical benefits. Through the genius of evolution, the Earth has selected fungal networks as a governing force managing ecosystems. This sentient network responds quickly to catastrophia. I believe the mycelium is Earth’s natural Internet, a neural network of communicating cells. All landmasses are criss-crossed with interspersing mosaics of mycelial colonies. With more than a mile of cells in a cubic inch of soil, the fungi are moving steadily, although silently all around us. This vast mass of cells, in the hundreds of billions of tons, represents a collective intelligence, like a computer honed to improve itself. Only now are scientists discovering that it is the microbial community upon which all higher life forms are dependent. And only now do we know how to join in alliance with them to improve life. As we begin a new century, myco-technology is a perfect example of the equation of good environmentalism, good health, and good business.

This book strives to create new models for the future use of higher fungi in the environment. As woodland habitats, especially old growth forests, are lost to development, mushroom diversity also declines. Wilderness habitats still offer vast genetic resources for new strains. The temperate forests of North America, particularly the mycologically rich Pacific Northwest, may well be viewed in the twenty-first century as pharmaceutical companies viewed the Amazon Basin earlier in the twentieth century. Hence, mushroom cultivators should preserve this gene pool now for its incalculable, future value. The importance of many mushroom species may not be recognized for decades to come.

In many ways, this book is an offspring of the marriage of many cultures arising from the worldwide use of mushrooms as food, as religious sacraments in Mesoamerica, and as medicine in Asia. We now benefit from the collective experience of lifetimes of mushroom cultivation. As cultivators we must continue to share, explore, and expand the horizons of the human/fungal relationship. In the future, humans and mushrooms must bond in an evolutionary partnership. By empowering legions of individuals with the skills of tissue culture and mycelial management, future generations will be able to better manage our resources and improve life on this planet.

Now that the medical community widely recognizes the health-stimulating properties of mushrooms, a combined market for gourmet and medicinal foods is rapidly emerging. People with compromised immune systems would be wise to create their own medicinal mushroom gardens. I envision the establishment of a community-based, resource-driven industry, utilizing recyclable materials in a fashion that strengthens ecological equilibrium and human health. As recycling centers flourish, their by-products include streams of organic waste, which cultivators can divert into mushroom production.

I foresee a network of environmentally sensitive and imaginative individuals presiding over this new industry, which has previously been controlled by a few mega-businesses. The decentralization began with The Mushroom Cultivator in 1983, and continues with Growing Gourmet and Medicinal Mushrooms. Join me in the next phase of this continuing revolution.

I first acknowledge the Mushrooms who have been my greatest teachers. They are the Body Intellect, the Neural Network of this book.

My family has been extremely patient and forgiving during this multiyear project. Azureus and LaDena have tolerated my insistent need for their modeling talents and have helped on many mushroom projects. Dusty Wu Yao is credited for her research skills, support, humor, and love.

My parents have taught me many things. My father championed education and science and impressed upon me that a laboratory is a natural asset to every home. My mother taught me patience and kindness, and that precognition is a natural part of the human experience. My brother John first piqued my interest for mushrooms upon his return from adventures in Colombia and Mexico. Additionally, his knowledge on the scientific method of photography has greatly helped improve my own techniques. In some mysterious way, their combined influences set the stage for my unfolding love of fungi.

Other people warrant acknowledgement in their assistance in the completion of this book. Andrew Weil played a critical role in helping build the creative milieu, the wellspring of spiritual chi from which this manuscript flowed. Gary Lincoff was extremely helpful in uncovering some of the more obscure references and waged intellectual combat with admirable skill. Brother Bill Stamets is thanked for his critical editorial remarks. Satit Thaithatgoon, my friend from Thailand, is appreciated for his insights about mushroom culture and life. I must thank Kit and Harley Barnhart for their advice on photographic technique. Michael Beug deserves acknowledgment for his unwavering support through all these years. Erik Remmen kept me healthy and strong through the many years of rigorous training in the ancient and noble martial art of Hwarang Do.

Joseph Ammirati, David Arora, Julie Bennett, Alan and Arleen Bessette, David Brigham, Janet Butz, Jonathan Caldwell, Alice Chen, Jeff Chilton, Ken Cochran, Don Coombs, Kim and Troy Donahue, Robert Ellingham, Gaston Guzman, Paxton Hoag, John Holliday, Rick Hoss, Lou Hsu, Eric Iseman, Loren Israelson, Omon Isikhuemhen, Barbara King, Mike Knoke, Alexander Krenov, Gary Leatham, Andrew Lenzer, Mike Maki, Andrew H. Miller, Orson and Hope Miller, Scott Moore, Tomiro Motohashi, Peter Mohs, Yoshikazu Murai, Takashi Mizuno, Takeshi Nakazawa, Louise North, George Osgood, Christiane Pischl, David Price, Paul Przybylowicz, Warren Rekow, Scott Redhead, Rusty Rodriguez, Maggie Rogers, Luiz Amaro Pachoa de Silva, Bulmaro Solano, Lillian Stamets, David Sumerlin, Ralph Tew, Harry Thiers, Tom O’Dell, James Trappe, Solomon Wasser, Dusty Yao, and Rytas Vilgalys all helped in their own special ways.

The late Jim Roberts, of Lambert Spawn, gained my respect and admiration for his devotion to helping the gourmet mushroom industry. And, I will never forget the generosity shown to me by the late Alexander Smith and Daniel Stuntz who were instrumental in encouraging me to continue in the field of mycology—in spite of those who fervently opposed me.

Companies that unselfishly contributed photographic material to this work, and to whom I am grateful, are The BOTS Group, The Minnesota Forest Resource Center, The Growing Company, DXN Company, Morel Mountain, Organotech, and Ostrom’s Mushroom Farms. I would also like to thank The Mushroom Council and the American Mushroom Institute. The Evergreen State College generously supported my studies with Psilocybe mushrooms and in scanning electron microscopy.

Finally, I wish to acknowledge all those bewildered and bemushroomed researchers who have paved the way into the future. For your help on this odyssey through life, I will forever be in your debt.

Mushrooms have never ceased to amaze me. The more I study them, the more I realize how little I have known, and how much more there is to learn. For thousands of years, fungi have evoked a host of responses from people—from fear and loathing to reverent adulation. And I am no exception.

When I was a little boy, wild mushrooms were looked upon with foreboding. It was not as if my parents were afraid of them, but our Irish heritage lacked a tradition of teaching children anything nice about mushrooms. In this peculiar climate of ignorance, rains fell and mushrooms magically sprang forth, wilted in the sun, rotted, and vanished without a trace. Given the scare stories told about “experts” dying after eating wild mushrooms, my family gave me the best advice they could: Stay away from all mushrooms, except those bought in the store. Naturally rebellious, I took this admonition as a challenge, a call to arms, firing up an already overactive imagination in a boy hungry for excitement.

When we were seven, my twin brother and I made a startling mycological discovery—Puffballs! We were told that they were not poisonous but if the spores got into our eyes, we would be instantly blinded! This information was quickly put to good use. We would viciously assault each other with mature puffballs, which would burst upon impact and emit a cloud of brown spores. The battle would continue until all the puffballs in sight had been hurled. They provided us with hours of delight over the years. Neither one of us ever went blind—although we both suffer from very poor eyesight. You must realize that to a seven-year-old these free, ready-made missiles satisfied instincts for warfare on the most primal of levels. This is my earliest memory of mushrooms, and to this day I consider it to be a positive emotional experience. (Although I admit a psychiatrist might like to explore these feelings in greater detail.)

Not until I became a teenager did my hunter-gatherer instincts resurface, when a relative returned from extensive travels in South America. With a twinkle in his eyes, he spoke of his experiences with the sacred Psilocybe mushrooms. I immediately set out to find these species, not in the jungles of Colombia, but in the fields and forests of Washington State where they were rumored to grow. For the first several years, my searches provided me with an abundance of excellent edible species, but no Psilocybes. Nevertheless, I was hooked.

When hiking through the mountains, I encountered so many mushrooms. Each was a mystery until I could match them with descriptions in a field guide. I soon came to learn that a mushroom was described as “edible,” “poisonous,” or my favorite, “unknown,” based on the experiences of others like me, who boldly ingested them. People are rarely neutral in their opinion about mushrooms—either they love them or they hate them. I took delight in striking fear into the hearts of the latter group, whose illogical distrust of fungi provoked my overactive imagination.

When I enrolled in the Evergreen State College in 1975, my skills at mushroom identification earned the support of a professor with similar interests. My initial interest was taxonomy, and I soon focused on fungal microscopy. The scanning electron microscope revealed new worlds, dimensional landscapes I never dreamed possible. As my interest grew, the need for fresh material year-round became essential. Naturally, these needs were aptly met by learning cultivation techniques, first in petri dishes, then on grain, and eventually on a wide variety of materials. In the quest for fresh specimens, I had embarked upon an irrevocable path that would steer my life on its current odyssey.

Paul Stamets in the virgin rainforest of Washington State, in route to collect new strains of wild mushrooms.

Humanity’s use of mushrooms extends back to Paleolithic times. Few people—even anthropologists—comprehend how influential mushrooms have been in affecting the course of human evolution. They have played pivotal roles in ancient Greece, India, and Mesoamerica. True to their beguiling nature, fungi have always elicited deep emotional responses: from adulation by those who understand them to outright fear by those who do not.

The historical record reveals that mushrooms have been used for less than benign purposes. Claudius II and Pope Clement VII were both killed by enemies who poisoned them with deadly Amanitas. Buddha died, according to legend, from a mushroom that grew underground. Buddha was given the mushroom by a peasant who believed it to be a delicacy. In ancient verse, that mushroom was linked to the phrase “pig’s foot” but has never been identified. (Although Truffles grow underground, and pigs are used to find them, no deadly poisonous species are known.)

The oldest archaeological record of probable mushroom use is a Tassili image from a cave dating back 5000 years B.C. (Lhote, 1987). The artist’s intent is clear. Mushrooms with electrified auras are depicted outlining a bee-masked dancing shaman. The spiritual interpretation of this image transcends time and is obvious. No wonder the word “bemushroomed” has evolved to reflect the devout mushroom lover’s state of mind.

In the fall of 1991, hikers in the Italian Alps came across the well-preserved remains of a man who died over 5,300 years ago, approximately 1,700 years later than the Tassili cave artist. Dubbed the “Iceman” or “Oetzi” by the news media, he was well-equipped with a knapsack, flint axe, a string of dried Birch Polypores (Piptoporus betulinus), a tinder fungus (Fomes fomentarius), and another as-yet-unidentified mushroom that may have had magico-spiritual significance (Peintner et al. 1998). Polypores can be used as spunk for starting fires and medicine for treating wounds. Further, a rich tea with immuno-enhancing and antibacterial properties can be prepared by boiling these mushrooms. Equipped for traversing the high alpine wilderness, this intrepid adventurer had discovered the value of the noble polypores. Even today, this knowledge can be life-saving for anyone astray in the wilderness.

2000+ year-old Mesoamerican mushroom stone.

Fear of mushroom poisoning pervades every culture, sometimes reaching phobic extremes. The term mycophobic describes those individuals and cultures who look upon fungi with fear and loathing. The English and Irish epitomize mycophobic cultures. In contrast, mycophilic societies can be found throughout Asia and Eastern Europe, especially among Polish, Russian, and Italian peoples. These societies have enjoyed a long history of mushroom use, with as many as a hundred common names to describe the mushroom varieties they love.

An investment banker named R. Gordon Wasson intensively studied the use of mushrooms by diverse cultures. His studies concentrated on the use of mushrooms by Mesoamerican, Russian, English, and Indian cultures. With the French mycologist Dr. Roger Heim, Wasson published research on Psilocybe mushrooms in Mesoamerica, and on Amanita mushrooms in Eurasia/Siberia. Wasson’s studies spanned a lifetime marked by a passionate love for fungi. His publications include Mushrooms, Russia, and History; The Wondrous Mushroom: Mycolatry in Mesoamerica; Maria Sabina and Her Mazatec Mushroom Velada; and Persephone’s Quest: Entheogens and the Origins of Religion. More than any individual of the twentieth century, Wasson kindled interest in ethnomycology to its present state of intense study. Wasson died on Christmas Day in 1986.

One of Wasson’s most provocative findings can be found in Soma: Divine Mushroom of Immortality (1976) where he postulated that the mysterious Soma in Vedic literature, a red fruit leading to spontaneous enlightenment for those who ingested it, was actually a mushroom. The Vedic symbolism carefully disguised its true identity: Amanita muscaria, the hallucinogenic Fly Agaric. Many cultures portray Amanita muscaria as the archetypal mushroom, invoking both fear and admiration. Although some Vedic scholars disagree with his interpretation, Wasson’s exhaustive research still stands (Brough, 1971 and Wasson, 1972).

Meso-American mushroom stones, circa 300 B.C., from the Pacific slope of Guatemala.

Aristotle, Plato, Homer, and Sophocles all participated in religious ceremonies at Eleusis where an unusual temple honored Demeter, the Goddess of Earth. For over two millennia, thousands of pilgrims journeyed fourteen miles from Athens to Eleusis, paying the equivalent of a month’s wage for the privilege of attending the annual ceremony. The pilgrims were ritually harassed on their journey to the temple, apparently in good humor.

Upon arriving at the temple, they gathered in the initiation hall, a great telestrion. Inside the temple, pilgrims sat in rows that descended step-wise to a hidden, central chamber from which a fungal concoction was served. An odd feature was an array of columns, beyond any apparent structural need, whose designed purpose escapes archaeologists. The pilgrims spent the night together and reportedly came away forever changed. In this pavilion crowded with pillars, ceremonies occurred, known by historians as the Eleusinian Mysteries. No revelation of the ceremony’s secrets could be mentioned under the punishment of imprisonment or death. These ceremonies continued until repressed in the early centuries of the Christian era.

In 1977, at a mushroom conference on the Olympic Peninsula, R. Gordon Wasson, Albert Hofmann, and Carl Ruck first postulated that the Eleusinian Mysteries centered on the use of psychoactive fungi. Their papers were later published in a book entitled The Road to Eleusis: Unveiling the Secret of the Mysteries (1978). That Aristotle and other founders of Western philosophy undertook such intellectual adventures, and that this secret ceremony persisted for nearly 2,000 years, underscores the profound impact that fungal rites have had on the evolution of Western consciousness.

Pre-classic Mayan mushroom stone from Kaminaljuyu Highlands of Guatemala, circa 500 B.C.

Mushrooms can be classified into three basic ecological groups: mycorrhizal, parasitic, and saprophytic. Although this book centers on the cultivation of the gourmet and medicinal saprophytic species, other mushrooms are also discussed.

The Mycorrhizal Gourmet Mushrooms: Matsutake, Boletus, Chanterelles, and Truffles

Mycorrhizal mushrooms form a mutually dependent, beneficial relationship with the roots of host plants, ranging from trees to grasses. “Myco” means mushrooms, while “rhizal” means roots. The collection of filament of cells that grow into the mushroom body is called the mycelium. The mycelia of these mycorrhizal mushrooms can form an exterior sheath covering the roots of plants and are called ectomycorrhizal. When they invade the interior root cells of host plants they are called endomycorrhizal. In either case, both organisms benefit from this association. Plant growth is accelerated. The resident mushroom mycelium increases the plant’s absorption of nutrients, nitrogenous compounds, and essential elements (phosphorus, copper, and zinc). By growing beyond the immediate root zone, the mycelium channels and concentrates nutrients from afar. Plants with mycorrhizal fungal partners can also resist diseases far better than those without.

Most ecologists now recognize that a forest’s health is directly related to the presence, abundance, and variety of mycorrhizal associations. The mycelial component of topsoil within a typical Douglas fir forest in the Pacific Northwest approaches 10% of the total biomass. Even this estimate may be low, not taking into account the mass of the endomycorrhizae and the many yeast-like fungi that thrive in the topsoil.

The nuances of climate, soil chemistry, and predominant microflora play determinate roles in the cultivation of mycorrhizal mushrooms in natural settings. Species native to a region are likely to adapt much more readily to designed habitats than exotic species. I am much more inclined to spend time attempting the cultivation of native mycorrhizal species than to import exotic candidates from afar. Here is a relevant example.

A Truffle market in France.

Truffle orchards are well established in France, Spain, and Italy, with the renowned Perigold Black Truffle, Tuber melanosporum, fetching up to $500 per pound. Only in the past thirty years has tissue culture of Truffle mycelia become widely practiced, allowing the development of planted Truffle orchards. Landowners seeking an economic return without resorting to cutting trees are naturally attracted to this prospective investment. The idea is enticing. Think of having an orchard of oaks or filberts, yielding pounds of Truffles per year for decades at several hundred dollars a pound! Several companies in this country have, in the past twenty years, marketed Truffle-inoculated trees for commercial use. Calcareous soils (i.e., high in calcium) in Texas, Washington, and Oregon have been suggested as ideal sites. Tens of thousands of dollars have been exhausted in this endeavor. Only two would-be Truffle orchards have had any success thus far, with only a small percentage of trees producing. This discouraging state of affairs should be fair warning to investors seeking profitable enterprises in the arena of Truffle cultivation. Suffice it to say that the only ones to have made money in the Truffle tree industry are those who have resold “inoculated” seedlings to other would-be trufflateurs.

A group of Oregon trufflateurs has been growing the Oregon White Truffle, Tuber gibbosum. Douglas fir seedlings are inoculated with mycelium from this native species and planted in plots similar to Christmas tree farms. Several years pass before the first harvests begin. However, since Oregon White Truffles were naturally occurring nearby, whether or not the inoculation process caused the truffles to form is unclear.

In Sweden, Eric Danell (1994; 1997), who is the first to grow Chantarelles (Cantharellus cibarius) with a potted pine tree in a greenhouse, is continuing an ambitious project of cultivating mycorrhizal mushrooms using a community of microorganisms as allies. (See photo here.) At the Invermay Agricultural Center in New Zealand, scientists have succeeded in inoculating pines with Matsutake (Tricholoma magnivelare) mycelia in the hope that mushrooms will appear a decade later. In New Zealand, mycorrhizal inoculations are more successful because of the extremely limited number of natural mycorrhizal candidates, in contrast to the hundreds seen in the forestlands of North America. These pilot projects hold great promise for replenishing the fungal genome of threatened mycorrhizal mushrooms in endangered ecosystems.

Mycorrhizal mushrooms in Europe have suffered a radical decline in years of late. The combined effects of acid rain and other industrial pollutants, even the disaster at Chernobyl, have been suggested to explain the sudden decline of both the quantity and diversity of wild mycorrhizal mushrooms. Most mycologists believe the sudden availability of deadwood is responsible for the comparative increase in the numbers of saprophytic mushrooms. The decline in Europe portends, in a worst case scenario, a total ecological collapse of the mycorrhizal community, followed by a widespread die-back of the forests. In the past ten years, the diversity of mycorrhizal mushrooms in Europe has fallen by more than 50%! Some species, such as the Chanterelle, have all but disappeared from regions in the Netherlands where it was abundant only twenty years ago (see Arnolds, 1992; Leck, 1991; Lizon 1993, 1995). Many biologists view these mushrooms as indicator species, the first domino to fall in a series leading to the failure of the forest’s life-support systems.

One method for inoculating mycorrhizae calls for the planting of young seedlings near the root zones of proven Truffle trees. The new seedlings acclimate and become “infected” with the mycorrhizae of a neighboring, parent tree. In this fashion, a second generation of trees carrying the mycorrhizal fungus is generated. After a few years, the new trees are dug up and replanted into new environments. This method has had the longest tradition of success in Europe.

Scanning electron micrograph of an emerging root tip being mycorrhized by mushroom mycelia.

Scanning electron micrograph of mycelia encasing the root of a tree, known as ectomycorrhizae.

Another approach, modestly successful, is to dip exposed roots of seedlings into water enriched with the spore-mass of a mycorrhizal candidate. First, mushrooms are gathered from the wild and soaked in water. Thousands of spores are washed off the gills, resulting in an enriched broth of inoculum. A spore-mass slurry coming from several mature mushrooms and diluted into a 5-gallon bucket can inoculate a hundred or more seedlings. The concept is wonderfully simple. Unfortunately, success is not guaranteed.

Broadcasting spore-mass onto the root zones of likely candidates is another venue that costs little in time and effort. Habitats should be selected on the basis of their parallels in nature. For instance, Chanterelles can be found in oak forests of the Midwest and in Douglas fir forests of the West. Casting spore-mass of Chanterelles into forests similar to those where Chanterelles proliferate is obviously the best choice. Although the success rate is not high, the rewards are well worth the minimum effort involved. Bear in mind that tree roots confirmed to be mycorrhized with a gourmet mushroom will not necessarily result in harvestable mushrooms. Fungi and their host trees may have long associations without the appearance of edible fruitbodies. (For more information, consult Fox, 1983.)

On sterilized media, most mycorrhizal mushrooms grow slowly, compared to the saprophytic mushrooms. Their long evolved dependence on root by-products and complex soils makes media preparation inherently more complicated. Some mycorrhizal species, like Pisolithus tinctorius, a puffball favoring pines, grow quite readily on sterilized media. A major industry has evolved providing foresters with seedlings inoculated with this fungus. Mycorrhized seedlings are healthier and grow faster than non-mycorrhized ones. Unfortunately, the gourmet mycorrhizal mushroom species do not fall into the readily cultured species category. The famous Matsutake may take weeks before its mycelium fully colonizes the media on a single petri dish! Unfortunately, this rate of growth is the rule rather than the exception with the majority of gourmet mycorrhizal species.

The first authenticated success in the cultivation of the Chantarelle: Pinus sylvestris in companionship with Cantharellus cibarius.

Chanterelles are one of the most popularly collected wild mushrooms. In the Pacific Northwest of North America the harvesting of Chanterelles has become a controversial, multi-million dollar business. Like Matsutake, Chanterelles also form mycorrhizal associations with trees. Additionally, they demonstrate a unique interdependence on soil yeasts and pseudomonads. This type of mycorrhizal relationship makes tissue culture most difficult. At least three organisms must be cultured simultaneously: the host tree, the mushroom, and soil microflora. A red soil yeast, Rhodotorula glutinis, is crucial in stimulating spore germination. The Chanterelle life cycle may have more dimensions of biological complexity. Cultivators have yet to grow Chanterelles to the fruitbody stage under laboratory conditions. Not only do other microorganisms play essential roles, the timing of their introduction appears critical to success in the mycorrhizal theater.

Senescence occurs with both saprophytic and mycorrhizal mushroom species. Often the first sign of senescence is not the inability of mycelia to grow vegetatively, but the loss of the formation of the sexually reproducing organ: the mushroom. Furthermore, the slowness from sowing the mycelium to the final stages of harvest confounds the quick feedback all cultivators need to refine their techniques. Thus, experiments trying to model how Matsutakes grow may take twenty to forty years each, the age the trees must be to support healthy, fruiting colonies of these prized fungi. Faster methods are clearly desirable, but presently only the natural model has shown any clue to success.

Given the huge hurdle of time for honing laboratory techniques, I favor the “low-tech” approach of planting trees adjacent to known producers of Chanterelles, Matsutake, Truffles, and Boletus. After several years, the trees can be uprooted, inspected for mycorrhizae, and replanted in new environments. The value of the contributing forest can then be viewed, not in terms of board feet of lumber, but in terms of its ability for creating satellite, mushroom/tree colonies. When industrial or suburban development threatens entire forests, and is unavoidable, future-oriented foresters may consider the removal of the mycorrhizae as a last-ditch effort to salvage as many mycological communities as possible by simple transplantation techniques, although on a much grander scale.

Until laboratory techniques evolve to establish a proven track record of successful marriages that result in harvestable crops, I hesitate to recommend mycorrhizal mushroom cultivation as an economic endeavor. Mycorrhizal cultivation pales in comparison to the predictability of growing saprophytic mushrooms like Oyster and Shiitake mushrooms. The industry simply needs the benefit of many more years of mycological research to better decipher the complex models of mycorrhizal mushroom cultivation.

Oyster and Honey mushrooms sharing a stump.

Parasitic Mushrooms: Blights of the Forest?

Parasitic fungi are the bane of foresters. They do immeasurable damage to the health of resident tree species, but in the process create new habitats for many other organisms. Although the ecological damage caused by parasitic fungi is well understood, we are only just learning of their importance in the forest ecosystem. Comparatively few mushrooms are true parasites.

Parasites live off a host plant, endangering the host’s health as it grows. Of all the parasitic mushrooms that are edible, the Honey mushroom, Armillaria mellea, is the best known. One of these Honey mushrooms, known as Armillaria gallica, made national headlines when scientists reported finding in Michigan a single colony covering 37 acres, weighing at least 220,000 pounds, with an estimated age of 1,500 years! Washington State soon responded with reports of a colony of Armillaria ostoyae covering 2,200 acres and at least 2,400 years old. With the exception of the trembling Aspen forests of Colorado, this fungus is the largest known living organism on the planet. And, it is a marauding parasite!

On a well-traveled trail in the Snoqualmie Forest of Washington State, hikers have been stepping upon the largest and perhaps oldest polypore: Bridgeoporus (Oxyporus) nobilissimus, a conk that grows up to several feet in diameter and can weigh hundreds of pounds!¹ This “parasitic” species grows primarily on old-growth Abies procera (California red fir) or on their stumps. Less than a dozen specimens have ever been collected. This mushroom is the first ever to be listed on any list, private or public, as an endangered species. Known only from the old-growth forests of the Pacific Northwest, the Noble Polypore’s ability to produce a conk that lives for hundreds of years distinguishes it from any other mushroom known to North America. This fact—that it produces a fruiting body that survives for centuries—suggests that the Noble Polypore has unique anti-rotting properties, antibiotics, or other compounds that could be useful medicinally. Located at the Kew Gardens in Scotland, another ancient polypore, Rigidioporus ulmarius, might also be medically significant, holding the Guinness Book of Records for the largest mushroom in the world—with an estimated weight of more than 625 pounds (284 kilograms). These examples from the fungal kingdom attract my attention in the search for candidates having potentially new medicines. With the loss of old-growth forests, cultivator–mycologists can play an all-important role in saving the fungal genome, especially in old-growth forests, a potential treasure trove of new medicines.

Intrepid amateur mycologist Richard Gaines points to parasitic fungus attacking a yew tree.

In the past, a parasitic fungus has been looked upon as biologically evil. This view is rapidly changing as science progresses. Montana State University researchers have discovered a new parasitic fungus attacking the yew tree. This new species is called Taxomyces andreanae and is medically significant for one notable feature: it produces minute quantities of the potent anticarcinogen Taxol, a proven treatment for breast cancer (Stone, 1993). This new fungus was studied and now a synthetic form of this potent drug is available for cancer patients. Recently, a leaf fungus isolated in the Congo has been discovered that duplicates the effect of insulin, but is orally active. Even well known medicines from fungi harbor surprises. A mycologist at Cornell University (Hodge et al. 1996) recently discovered that the fungus responsible for the multibillion dollar drug, cyclosporin, has a sexual stage in Cordyceps subsessilis, a parasitic mushroom attacking scarab beetle larvae. Of the estimated 1,500,000 species of fungi, approximately 70,000 have been identified (Hawksworth et al. 1995), and about 10,000 are mushrooms. We are just beginning to discover the importance of species hidden within this barely explored genome.

Many saprophytic fungi can be weakly parasitic in their behavior, especially if a host tree is dying from other causes. These can be called facultative parasites: saprophytic fungi activated by favorable conditions to behave parasitically. Some parasitic fungi continue to grow long after their host has died. Oyster mushrooms (Pleurotus ostreatus) are classic saprophytes, although they are frequently found on dying cottonwood, oak, poplar, birch, maple, and alder trees. These appear to be operating parasitically when they are only exploiting a rapidly evolving ecological niche.

Most of the parasitic fungi are microfungi and are barely visible to the naked eye. In mass, they cause the formation of cankers and shoot blights. Often their preeminence in a middle-aged forest is symptomatic of other imbalances within the ecosystem. Acid rain, groundwater pollution, insect damage, and loss of protective habitat all are contributing factors unleashing parasitic fungi. After a tree dies, from parasitic fungi or other causes, saprophytic fungi come into play.

The cultivation of the Button mushroom in caves near Paris in 1868. Note candle used for illumination. (Robinson, 1885)

Saprophytic Mushrooms: The Decomposers

Most of the gourmet mushrooms are saprophytic, wood-decomposing fungi. Saprophytic fungi are the premier recyclers on the planet. The filamentous mycelial network is designed to weave between and through the cell walls of plants. The enzymes and acids they secrete degrade large molecular complexes into simpler compounds. All ecosystems depend upon fungi’s ability to decompose organic plant matter soon after it is rendered available. The end result of their activity is the return of carbon, hydrogen, nitrogen, and minerals back into the ecosystem in forms usable to plants, insects, and other organisms. As decomposers, they can be separated into three key groups. Some mushroom species cross over from one category to another depending upon prevailing conditions.

Primary Decomposers: These are the fungi first to capture a twig, a blade of grass, a chip of wood, a log or stump. Primary decomposers are typically fast-growing, sending out ropy strands of mycelium that quickly attach to and decompose plant tissue. Most of the decomposers degrade wood. Hence, the majority of these saprophytes are woodland species, such as Oyster mushrooms (Pleurotus species), Shiitake (Lentinula edodes), and King Stropharia (Stropharia rugosoannulata). However, each species has developed specific sets of enzymes to break down lignin-cellulose, the structural components of most plant cells. Once the enzymes of one mushroom species have broken down the lignin-cellulose to its fullest potential, other saprophytes utilizing their own repertoire of enzymes can reduce this material even further.

Secondary Decomposers: These mushrooms rely on the previous activity of other fungi to partially break down a substrate to a state wherein they can thrive. Secondary decomposers typically grow from composted material. The actions of other fungi, actinomycetes, bacteria, and yeasts all operate within compost. As plant residue is degraded by these microorganisms, the mass, structure, and composition of the compost is reduced, and proportionately available nitrogen is increased. Heat, carbon dioxide, ammonia, and other gases are emitted as by-products of the composting process. Once these microorganisms (especially actinomycetes) have completed their life cycles, the compost is susceptible to invasion by a select secondary decomposer. A classic example of a secondary decomposer is the Button Mushroom, Agaricus brunnescens, the most commonly cultivated mushroom. Another example is Stropharia ambigua, which invades outdoor mushroom beds after wood chips have been first decomposed by a primary saprophyte.

Tertiary Decomposers: An amorphous group, the fungi represented by this group are typically soil dwellers. They survive in habitats that are years in the making from the activity of the primary and secondary decomposers. Fungi existing in these reduced substrates are remarkable in that the habitat appears inhospitable for most other mushrooms. A classic example of a tertiary decomposer is Aleuria aurantia, the Orange Peel Mushroom. This complex group of fungi often poses unique problems to would-be cultivators. Panaeolus subbalteatus is yet another example. Although one can grow it on composted substrates, this mushroom has the reputation of growing prolifically in the discarded compost from Button mushroom farms. Other tertiary decomposers include species of Conocybe, Agrocybe, Pluteus, and some Agaricus species.

The floor of a forest is constantly being replenished by new organic matter. Primary, secondary, and tertiary decomposers can all occupy the same location. In the complex environment of the forest floor, a “habitat” can actually be described as the overlaying of several, mixed into one. And, over time, as each habitat is being transformed, successions of mushrooms occur. This model becomes infinitely complex when taking into account the interrelationships of not only the fungi to one another, but also the fungi to other microorganisms (yeasts, bacteria, protozoa), plants, insects, and mammals.

Primary and secondary decomposers afford the most opportunities for cultivation. To select the best species for cultivation, several variables must be carefully matched.

Climate, available raw materials, and the mushroom strains all must interplay for cultivation to result in success. Native species are the best choices when you are designing outdoor mushroom landscapes.

Temperature-tolerant varieties of mushrooms are more forgiving and easier to grow than those that thrive within finite temperature limits. In warmer climates, moisture is typically more rapidly lost, narrowing the opportunity for mushroom growth. Obviously, growing mushrooms outdoors in a desert climate is more difficult than growing mushrooms in moist environments where they naturally abound. Clearly, the site selection of the mushroom habitat is crucial. The more exposed a habitat is to direct midday sun, the more difficult it is for mushrooms to flourish.

Many mushrooms actually benefit from indirect sunlight, especially in the northern latitudes. Pacific Northwest mushroom hunters have long noted that mushrooms grow most prolifically, not in the darkest depths of a woodlands, but in environments where shade and “dappled” sunlight are combined. Sensitivity-to-light studies have established that various species differ in their optimal response to wavebands of sunlight. Nevertheless, few mushrooms enjoy prolonged exposure to direct sunlight.

The Global Environmental Shift and the Loss of Species Diversity

Studies in Europe show a frightening loss of species diversity in forestlands, most evident with the mycorrhizal species. Many mycologists fear many mushroom varieties, and even species, will soon become extinct. As the mycorrhizal species decline in both numbers and variety, the populations of saprophytic and parasitic fungi initially rise as a direct result of the increased availability of deadwood debris. However, as woodlots are burned and replanted, the complex mosaic of the natural forest is replaced by a highly uniform, mono-species landscape. Because the replanted trees are nearly identical in age, the cycle of debris replenishing the forest floor is interrupted. This new “ecosystem” cannot support the myriad fungi, insects, small mammals, birds, mosses, and flora so characteristic of ancestral forests. In pursuit of commercial forests, the native ecology has been supplanted by a biologically anemic woodlot. This woodlot landscape is barren in terms of species diversity.

With the loss of every ecological niche, the sphere of biodiversity shrinks. At some presently unknown level, the diversity will fall below the critical mass needed for sustaining a healthy forestland. Once passed, the forest may not ever recover without direct and drastic counteraction: the insertion of multiage trees of different species, with varying canopies and undergrowth. Even with such extraordinary action, the complexity of a replanted forest cannot match that which has evolved for thousands of years. Little is understood about prerequisite microflora—yeasts, bacteria, and micro-fungi—upon which the ancient forests are dependent. As the number of species declines, whole communities of organisms disappear. New associations are likewise limited. If this trend continues, I believe the future of new forests, indeed the planet, is threatened.

Apart from the impact of wood harvest, the health of biologically diverse forests is in increasing jeopardy due to acid rain and other airborne toxins. Eventually, the populations of all fungi—saprophytic and mycorrhizal—suffer as the critical mass of dead trees declines more rapidly than it is replenished. North Americans have already experienced the results of habitat loss from the European forests. Importation of wild picked mushrooms from Mexico, the United States, and Canada to Europe has escalated radically in the past twenty years. This increase in demand is not due just to the growing popularity of eating wild mushrooms. It is a direct reflection of the decreased availability of wild mushrooms from regions of the world suffering from ecological shock. The woodlands of North America are only a few decades behind the forests of Europe and Asia.

With the loss of habitat of the mycorrhizal gourmet mushrooms, market demands for gourmet mushrooms should shift to those that can be cultivated. Thus, the pressure on this not-yet-renewable resource would be alleviated. I believe the judicious use of saprophytic fungi by homeowners as well as foresters may well prevent widespread parasitic disease vectors. Selecting and controlling the types of saprophytic fungi occupying these ecological niches can benefit both forester and forestland.

Catastrophia: Nature as a Substrate Supplier

Many saprophytic fungi benefit from catastrophic events in the forests. When hurricane-force winds rage across woodlands, enormous masses of dead debris are generated. The older trees are especially prone to fall. Once the higher canopy is gone, the growth of a younger, lower canopy of trees is triggered by the suddenly available sunlight. The continued survival of young trees is dependent upon the quick recycling of nutrients by the saprophytic fungi in decomposing deadwood.

Every time catastrophes occur—hurricanes, tornadoes, volcanoes, floods, and even earthquakes—the resulting deadwood becomes a stream of inexpensive substrate materials. In a sense, the cost of mushroom production is underwritten by natural disasters. Unfortunately, to date, few individuals and communities take advantage of catastrophia as a fortuitous event for enhancing mycelial growth. However, once the economic value of recycling with gourmet and medicinal mushrooms is clearly understood, and with the increasing popularity of backyard cultivation, catastrophia can be viewed as a positive event, at least in terms of providing new economic opportunities and positive environmental consequences for those who are mycologically astute.

Mushrooms and Toxic Wastes

In heavily industrialized areas, the soils are typically contaminated with a wide variety of pollutants, particularly petroleum-based compounds, polychlorinated biphenols (PCBs), heavy metals, pesticide-related compounds, and even radioactive wastes. Mushrooms grown in polluted environments can absorb toxins directly into their tissues, especially heavy metals (Bressa, 1988; Stijve 1974, 1976, 1992). As a result, mushrooms grown in these environments should not be eaten. Recently, a visitor to Ternobyl, a city about 60 miles from Chernobyl, the site of the world’s worst nuclear power plant accident, returned to the United States with a jar of pickled mushrooms. The mushrooms were radioactive enough to set off Geiger counter alarms as the baggage was being processed. Customs officials promptly confiscated the mushrooms. Unfortunately, most toxins are not so readily detected.

A number of fungi can, however, be used to detoxify contaminated environments, in a process called “bioremediation.” The white rot fungi (particularly Phanerochaete chrysosporium) and brown rot fungi (notably Gloephyllum species) are the most widely used. Most of these wood-rotters produce lignin peroxidases and cellulases, which have unusually powerful degradative properties. These extracellular enzymes have evolved to break down plant fiber, primarily lignin-cellulose, the structural component in woody plants, into simpler forms. By happenstance, these same enzymes also reduce recalcitrant hydrocarbons and other manufactured toxins. Given the number of industrial pollutants that are hydrocarbon-based, fungi are excellent candidates for toxic waste cleanup and are viewed by scientists and government agencies with increasing interest. Current and prospective future uses include the detoxification of PCB (polychloralbiphenols), PCP (pentachlorophenol), oil, and pesticide/herbicide residues. They are even being explored for ameliorating the impact of radioactive wastes by sequestering heavy metals.

A far-reaching patent has been applied for using mycelial mats to break down toxic wastes, particularly those that are hydrocarbon based, including most petroleum products, pesticides, PCBs (polychlorobiphenols), and PCPs (pentachlorophenols), and for eliminating the flow of pathogenic bacteria into sensitive watersheds. This revolutionary patent also describes methods for effectively destroying nerve gas surrogates, including Sarin and VX, as well as chemical and biological warfare components by training the mushroom mycelium (Venter, A. J., 1999; Word et al. 1997; Thomas et al. 1998).

Bioremediation of toxic waste sites is especially attractive because the environment is treated in situ. The contaminated soils do not have to be hauled away, eliminating the extraordinary expense of handling, transportation, and storage. Since these fungi have the ability to reduce complex hydrocarbons into elemental compounds, these compounds pose no threat to the environment. Indeed, these former pollutants could even be considered “fertilizer,” helping rather than harming the nutritional base of soils.

Dozens of bioremediation companies have formed to solve the problem of toxic waste. Most of these companies look to the imperfect fungi. The higher fungi should not be disqualified for bioremediation just because they produce an edible fruitbody. Indeed, this group may hold answers to many of the toxic waste problems. The most vigorous rotters described in this book are the Ganoderma and Pleurotus mushrooms. Mushrooms grown from toxic wastes are best not eaten, as residual heavy metal toxins may be concentrated within the mushrooms. However, one experiment using Oyster mushrooms to degrade petroleum residues on an oil-saturated Department of Transportation lot near Bellingham, Washington, not only largely decomposed the oil, but the mushrooms were free of petroleum residues when analyzed (Stamets, 1999).

Scanning electron micrograph of the mycelial network.

Mushroom Mycelium and Mycofiltration

The mycelium is a fabric of interconnected, interwoven strands of cells. One colony can range in size from a half-dollar to many acres. A cubic inch of soil can host up to a mile of mycelium. This organism can be physically separated, and yet behave as one.

The exquisite lattice-like structure of the mushroom mycelium, often referred to as the mycelial network, is perfectly designed as a filtration membrane. Each colony extends long, complex chains of cells that fork repeatedly in matrix-like fashion, spreading to geographically defined borders. The mushroom mycelium, being a voracious forager for carbon and nitrogen, secretes extracellular enzymes that unlock organic complexes. The newly freed nutrients are then selectively absorbed directly through the cell walls into the mycelial network.

In the rainy season, water carries nutritional particles through this filtration membrane, including bacteria, which often become a food source for the mushroom mycelium. The resulting downstream effluent is cleansed of not only carbon/nitrogen-rich compounds but also bacteria, in some cases nematodes, and legions of other microorganisms. The voracious Oyster mushrooms been found to be parasitic against nematodes (Thorn and Barron, 1984; Hibbett and Thorn, 1994). Extracellular enzymes act like an anesthetic and stun the nematodes, thus allowing the invasion of the mycelium directly into their immobilized bodies.

The use of mycelium as a mycofilter is currently being studied by this author in the removal of biological contaminants from surface water passing directly into sensitive watersheds. By placing sawdust implanted with mushroom mycelium in drainage basins downstream from farms raising livestock, the mycelium acts as a sieve, which traps fecal bacteria and ameliorates the impact of a farm’s nitrogen-rich outflow into aquatic ecosystems. This concept is incorporated into an integrated farm model and explored in greater detail in Chapter 5: Permaculture with a Mycological Twist.

Oyster mushrooms fruiting on diesel-contaminated soil at a test bioremediation site near Bellingham, Washington, effectively “de-contaminating” the soil to a level where it could be used for highway landscaping.

Many mushroom hunters would love to have their favorite edible mushroom growing in their backyard. Who would not want a patch of Matsutake, Shaggy Manes, Giant Puffballs, or the stately Prince gracing their property? As the different seasons roll along, gourmet mushrooms would arise in concert. Practically speaking, however, our knowledge of mushroom cultivation is currently limited to 100 species of the 10,000 thought to exist throughout the world. Through this book and the works of others, the number of cultivatible species will enlarge, especially if amateurs are encouraged to boldly experiment. Techniques for cultivating one species may be applied for cultivating another, often by substituting an ingredient, changing a formula, or altering the fruiting environment. Ironically, with species never before grown, the strategy of “benign neglect” more often leads to success than active interference with the natural progression of events. I have been particularly adept at this nonstrategy. Many of my early mushroom projects only produced when I left them alone.

A list of candidates, which can be grown using current methods, follows. Currently we do not know how to grow those species marked by an asterisk (*). However, I believe techniques for their cultivation will soon be perfected, given a little experimentation. This list is by no means exhaustive, and will be much amended in the future. Many of these mushrooms are described as good edibles in the field guides, as listed in the Resource Directory in this book. (See Appendix 4.)

Woodland Mushrooms

Grassland Mushrooms

Dung Inhabiting Mushrooms

Compost/Litter/Disturbed Habitat Mushrooms

Termitomyces robustus is one of the best of the edible mushrooms but defies human attempts at cultivation. So far only ants know the secret to growing this delicacy.

Gardening with gourmet and medicinal mushrooms.

Natural culture is the cultivation of mushrooms outdoors. After mycological landscapes are constructed and inoculated, the forces of nature take control. For these mycological landscapes to be sustainable, a continual flow of organic debris is essential. Although the cultivator may choose to install desired species, respect towards nature’s selection of preferred mushrooms is the only path to successful cultivation. Wild species in the landscape are natural allies. The responsibility of the cultivator is to design a habitat incorporating both wild and cultivated mushrooms, and seeking the right fits. Yet, the complex nature of creating species mosaics is still being understood. Only through the cumulative experiences of mycological landscapers can the knowledge base of this new model expand.

I also call this laissez-faire cultivation. After the mushroom patch has been inoculated, it is left alone, subject to the whims of nature, except for some timely watering. The mushroom habitat is specifically designed, paying particular attention to site location, topography, sun exposure, and the use of native woods and/or garden by-products. Once prepared, the cultivator launches the selected mushroom species into a constructed habitat by spawning. In general, native mushroom species do better than exotic ones. However, even those obstacles to growing exotic species are easily overcome with some forethought to design, and the helpful suggestions of an experienced cultivator.

Every day, gardeners, landscapers, rhododendron growers, arborists, and nurseries utilize the very components needed for growing mushrooms. Every pile of debris, whether it is tree trimmings, sawdust, wood chips, or a mixture of these materials, will support mushrooms. Unless selectively inoculated, debris piles become habitats of miscellaneous “weed” mushrooms, making the likelihood of growing a desirable mushroom remote.

When inoculating an outdoor environment with mushroom spawn, the cultivator relinquishes much control to natural forces. There are obvious advantages and disadvantages to natural culture. First, the mushroom patch is controlled by volatile weather patterns. This also means that outdoor beds have the advantage of needing minimum maintenance. The ratio of hours spent per pound of mushrooms grown becomes quite efficient. The key to success is creating an environment wherein the planted mycelium naturally and vigorously expands. A major advantage of growing outdoors compared to growing indoors is that competitors are not concentrated in a tight space. When cultivating mushrooms outdoors entropy is your ally.

The rate of growth, time to fruiting, and quality of the crop depends upon the quality of the spawn, substrate materials, and weather conditions. Generally, when mushrooms are fruiting in the wild, the inoculated patches also produce. Mushrooms that fruit primarily in the summer, such as the King Stropharia (Stropharia rugosoannulata) require frequent watering. Shaggy Manes (Coprinus comatus) prefer the cool fall rains, thus requiring little attention. In comparison to indoor cultivation, the outdoor crops are not as frequent. However, the crops can be just as intense, sometimes more so, especially when paying modest attention to the needs of the mushroom mycelium at critical junctions in its life cycle.

While the cultivator is competing with molds indoors, wild mushrooms are the major competitors outdoors. You may plant one species in an environment where another species is already firmly established. This is especially likely if you use old sawdust, chips, or base materials. Starting with fresh materials is the simplest way to avoid this problem. Piles of aged wood chips commonly support four or five species of mushrooms within just a few square feet. Unless, the cultivator uses a high rate of inoculation (25% spawn/substrate) and uniformly clean wood chips, the concurrence of diverse mushroom species should be expected. If, for instance, the backyard cultivator gets mixed wood chips in the early spring from a county road maintenance crew, and uses a dilute 5–10% inoculation rate of sawdust spawn into the chips, the mushroom patch is likely to have more wild species emerging along with the desired mushrooms.

In the Pacific Northwest of North America, I find a 5–10% inoculation rate usually results in some mushrooms showing late in the first year, the most substantial crops occurring in the second and third years, and a dramatic drop-off in the fourth year. As the patch ages, it is normal to see more diverse mushroom varieties co-occurring with the planted mushroom species.

I am constantly fascinated by the way nature reestablishes a polyculture environment at the earliest opportunity. Some mycologists believe a predetermined sequence of mycorrhizal and saprophytic species prevails, for instance, around a Douglas fir tree, as it matures. In complex natural habitats, the interlacing of mycelial networks is common. Underneath a single tree, twenty or more species may thrive. I look forward to the time when mycotopian foresters will design whole species mosaics upon whose foundation vast ecosystems can flourish. This book will describe simpler precursor models for mixing and sequencing species. I hope imaginative and skilled cultivators will further develop these concepts.

In one of my outdoor wood-chip beds, I created a “polyculture” mushroom patch about 50 by 100 feet in size. In the spring I acquired mixed wood chips from the county utility company—mostly alder and Douglas fir—and inoculated three species into it. One year after inoculation, in late April through May, Morels showed. From June to early September, King Stropharia erupted with force, providing our family with several hundred pounds. In late September through much of November, an assortment of Clustered Woodlovers (Hypholoma-like) species popped up. With noncoincident fruiting cycles, this Zen-like polyculture approach is limited only by your imagination.

Species succession can be accomplished indoors. Here is one example. After Shiitake stops producing on logs or sawdust, the substrate can be broken apart, remoistened, resterilized, and reinoculated with another gourmet mushroom; in this case, I recommend Oyster mushrooms. Once the Oyster mushroom life cycle is completed, the substrate can be again sterilized, and inoculated with the next species. Shiitake, Oyster, King Stropharia, and finally Shaggy Manes can all be grown on the same substrate, increasingly reducing the substrate mass, without the addition of new materials. The majority of the substrate mass that does not evolve into gases, is regenerated into mushrooms. The conversion of substrate mass-to-mushroom mass is mind boggling. These concepts are further developed in Chapter 22.

The following is a list of decomposer mushrooms most frequently occurring in wood chips in the northern temperate regions of North America. In general, these natural competitors are easy to distinguish from the gourmet mushroom species described in this book. Those that are mildly poisonous are labeled with^*; those that are deadly have two^**. This list is by no means comprehensive. Many other species, especially the poisonous mycorrhizal Amanita, Hebeloma, Inocybe, and Cortinarius species are not listed here. Mushrooms from these genera can inhabit the same plot of ground where a cultivator may lay down wood chips, even if the host tree is far removed.

The mushrooms in the Galerina autumnalis and Pholiotina filaris groups are deadly poisonous. Some species in the genus Psilocybe contain psilocybin and psilocin, compounds that often cause uncontrolled laughter, hallucinations, and sometimes spiritual experiences. Outdoor cultivators must hone their skills at mushroom identification to avert the accidental ingestion of a poisonous mushroom. Recommended mushroom field guides and mushroom identification courses are listed in the Resource Directory in this book.

Some Wild Mushrooms Naturally Found in Beds of Wood Chips

Methods of Mushroom Culture

Mushrooms can be cultivated through a variety of methods. Some techniques are exquisitely simple, and demand little or no technical expertise. Others—involving sterile tissue culture—are much more technically demanding. The simpler methods take little time, but also require more patience and forgiveness on the part of the cultivator, lest the mushrooms do not appear on your timetable. As one progresses to the more technically demanding methods, the probability of success is substantially increased, with mushrooms appearing exactly on the day scheduled.

The simpler methods for mushroom cultivation, demanding little or no technical expertise, are outlined in this chapter. They are spore-mass inoculation, transplantation, and inoculation with pure cultured spawn.

Collecting the spores of the delicious Lepiota rachodes, a Parasol Mushroom, on two panes of glass, which are then folded together, creating a spore booklet.

Spore-Mass Inoculation

By far the simplest way to grow mushrooms is to broadcast spores onto prepared substrates outdoors. First, spores of the desired species must be collected. Spore collection techniques vary, according to the shape, size, and type of the mushroom candidate.

For gilled mushrooms, the cap can be severed from the stem, and laid, gills down, on top of clean typing paper, glass, or similar surface. A glass jar or bowl is placed over the mushroom to lessen the loss of water. After 12 hours, most mushrooms will have released thousands of spores, falling according to the radiating symmetry of the gills, in a symmetrically attractive outline called a sporeprint. This method is ideal for mushroom hunters “on the go” who might not be able to make use of the spores immediately. After the spores have fallen, the spore print can be sealed, stored, and saved for future use. It can even be mailed without harm.

By collecting spores of many mushrooms, one creates a species library. Spore collections can resemble stamp or coin collections, but are potentially more valuable. A mushroom hunter may find a species only once in a lifetime. Under these circumstances, the existence of a spore print may be the only resource a cultivator has for future propagation. I prefer taking spore prints on panes of glass, using duct tape as binding along one edge. The glass panes are folded together, and masking tape is used to seal the three remaining edges. This spore booklet is then registered with written notes affixed to its face as to the name of mushroom, the date of collection, the county and locality of the find. Spores collected in this fashion remain viable for years, although viability decreases over time. They should be stored in a dark, cool location, low in humidity and free from temperature fluctuation. Techniques for creating cultures from spores are explained further on.

For those wishing to begin a mushroom patch using fresh specimens, a more efficient method of spore collection is recommended. This method calls for the immersion of the mushroom in water to create a spore-mass slurry. Choose fairly mature mushrooms and submerge them in a 5-gallon bucket of water. A gram or two of table salt inhibits bacteria from growing while not substantially affecting the viability of the spores. With the addition of 50 milliliters of molasses, spores are stimulated into frenzied germination. After 4 hours of soaking, remove the mushrooms from the bucket. Most mushrooms will have released tens of thousands of spores. Allow the broth to sit for 24 to 48 hours at a temperature above 50°F (10°C) but under 80°F (26.7°C). In most cases, spores begin to germinate in minutes to hours, aggressively in search of new mates and nutrients. This slurry can be expanded by a factor of 10 in 48 hours. I have often dreamed, being the mad scientist that I am, of using spore-mass slurries of Morels and other species to aerially “bomb” large expanses of forestlands. This idea, as crazy as it may initially sound, warrants serious investigation.

During this stage of frenzied spore germination, the mushroom patch habitat should be designed and constructed. Each species has unique requirements for substrate components for fruiting. However, mycelia of most species will run through a variety of lignin-cellulosic wastes. Only at the stage when fruitbody production is sought does the precise formulation of the substrate become crucial.

Oyster (Pleurotus ostreatus; P. eryngii, and allies), King Stropharia (Stropharia rugosoannulata), and Shaggy Mane (Coprinus comatus) mushrooms thrive in a broad range of substrate formulations. Other mushrooms such as Morels (Morchella angusticeps and esculenta) are more restrictive in their requirements. Since there are several tracks that one can pursue to create suitable habitats, refer to Chapter 21 for more information.

Transplantation: Mining Mycelium from Wild Patches

Transplantation is the moving of mycelium from natural patches to new habitats. Most wild mushroom patches have a vast mycelial network emanating from beneath each mushroom. Not only can one harvest the mushroom, but portions of the mycelial network can be gathered and transferred to a new location. This method ensures the quick establishment of a new colony without having to germinate spores or buy commercial spawn.

When transplanting mycelium, I use a paper sack or a cardboard box. Once mycelium is disturbed, it quickly dries out unless measures are taken to prevent dehydration. After it is removed from its original habitat, the mycelium will remain viable for days or weeks, as long as it is kept moist in a cool, dark place.

Gathering the wild mycelium of mycorrhizal mushrooms could endanger the parent colony. Be sure you cover the divot with wood debris and press tightly back into place. In my opinion, mycorrhizal species should not be transplanted unless the parent colony is imminently threatened with loss of habitat—such as logging, construction, etc. Digging up mycelium from the root zone of a healthy forest can jeopardize the symbiotic relationship between the mushroom and its host tree. Exposed mycelium and roots become vulnerable to disease, insect invasion, and dehydration. Furthermore, transplantation of mycorrhizal species has a lower success rate than the transplantation of saprophytic mushrooms.

If done properly, transplanting the mycelium of saprophytic mushrooms is not threatening to naturally occurring mushroom colonies. Some of the best sites for finding mycelium for transplantation are sawdust piles. Mycelial networks running through sawdust piles tend to be vast and relatively clean of competing fungi. Fans of mycelium are more often found along the periphery of sawdust piles than within their depths. When sawdust piles are a foot deep or more, the microclimate is better suited for molds and thermophilic fungi. These mold fungi benefit from the high carbon dioxide and heat generated from natural composting. At depths of 2–6 inches, mushroom mycelia run vigorously. It is from these areas that mushroom mycelium should be collected for transplantation to new locations. One, in effect, engages in a form of mycelial mining by encouraging the growth and the harvesting of mycelium from such environments. Ideal locations for finding such colonies are sawmills, nurseries, composting sites, recycling centers, rose and rhododendron gardens, and soil mixing companies.

Establishing an outdoor mushroom bed in a garden.

Sprinkling spawn on top of mulch layer.

Adding more moist mulch over the spawn layer.

Cross section of garden bed showing mycelium and mushroom growth.

Inoculating Outdoor Substrates with Pure Cultured Spawn

In the early history of mushroom cultivation, mycelium was collected from the wild and transplanted into new substrates with varying results. Soon compost spawn (for the Button Mushroom, Agaricus brunnescens) evolved with greater success. In 1933, spawn technology was revolutionized by Sinden’s discovery of grain as a spawn carrier medium. Likewise, Stoller (1962) significantly contributed to the technology of mushroom cultivation through a series of practical advances in using plastic bags, collars, and filters.¹ The Mushroom Cultivator (Stamets and Chilton, 1983) explained the process of producing tissue culture for spawn generation, empowering far more cultivators than ever before. Legions of creative individuals embarked on the path of exotic mushroom production. Today, thousands of cultivators are contributing to an ever-expanding body of knowledge, and setting the stage for the cultivation of many gourmet and medicinal fungi of the future.

The advantage of using commercial spawn is in acquiring mycelium of higher purity than can be harvested from nature. Commercial spawn can be bought in two forms: grain or wood (sawdust or plugs). For the inoculation of outdoor, unpasteurized substrates, wood-based spawn is far better than grain spawn. When grain spawn is introduced to an outdoor bed, insects, birds, and slugs quickly seek out the nutritious kernels for food. Sawdust spawn has the added advantage of having more particles or inoculation points per pound than does grain. With more points of inoculation, colonization is accelerated. The distances between mycelial fragments are lessened, making the time to contact less than that with grain spawn. Thus the window of vulnerability is closed to many of the diseases that eagerly await intrusion.

Before spawn is used, the receiving habitat is moistened to near saturation. The spawn is then mixed thoroughly through the new habitat with your fingers or a rake. Once inoculated, the new bed is again watered. The bed can be covered with cardboard, shade cloth, scrap wood, or a similar material to protect the mycelium from sun exposure and dehydration. After inoculation, the bed is ignored, save for an occasional inspection and watering once a week, and then only when deemed necessary.

Certain limitations prevail in the expansion of mycelium and its ability for colonizing new substrates. The intensity or rate of inoculation is extremely important. If the spawn is too dispersed into the substrate, the points of inoculation will not be close enough to result in the rapid reestablishment of one large contiguous mycelial mat. My own experiences show that success is seen with an inoculation rate of 5–50%, with an ideal of 20%. In other words, if you gather a 5-gallon bucket of naturally occurring mycelium, 20 gallons of prepared substrate can be inoculated with a high probability of success. Although this inoculation rate may seem high, rapid colonization is assured. More skilled cultivators, whose methods have been refined through experience, often use a less intensive inoculation rate of 10%. Inoculation rates of 5% or less often result in “island” colonies of the implanted species interspersed among naturally occurring wild colonies.

At a 20% inoculation rate, colonization can be complete in as short as 1 week and as long as 8 weeks. After a new mycelial mat has been fully established, the cultivator has the option of further expanding the colony by a factor of 5, or triggering the patch into fruiting. This usually means providing shade and frequent watering. Should prevailing weather conditions not be conducive to fruiting and yet are above freezing, then the patch can be further expanded. Should the cultivator not expect that further expansion would result in full colonization by the onset of winter, then no new raw material should be added, and mushrooms should be encouraged to form. The widely cast mycelial mat, more often than not, acts as a single organism. At the time when mushrooms are forming, colonization of new organic debris declines or abates entirely. The energy of the mycelium is now channeled to fruitbody formation and development.

Healthy Stropharia rugosoannulata mycelium tenaciously gripping alder chips and sawdust. Note rhizomorphs.

From the same patch, a year later, the wood chips have decomposed into a rich soil-loam.

The mycelium of saprophytic mushrooms must move to remain healthy. When the mycelium reaches the borders of a geographically or nutritionally defined habitat, a resting period ensues. If not soon triggered into fruiting, over-incubation is likely, with the danger of “dieback.” Only very cold temperatures will keep the patch viable for a prolonged period. Typically, dieback is seen as the drastic decline in vigor of the mycelium. Once the window of opportunity has passed for fruiting, the mushroom patch might be salvaged by the reintroduction of more undecomposed organic matter, or by violent disturbance. The mycelium soon becomes a site for contamination with secondary decomposers (weed fungi) and predators (insects) coming into play. It is far better is to keep the mycelium running until fruitings can be triggered at the most opportune time. Mushroom patches are, by definition, temporary communities.

King Stropharia lasts 3 to 4 years on a hardwood chip base. After the second year more material should be added. However, if the health of the patch has declined and new material is mixed in, then the mushroom patch may not recover to its original state of vigor. Mycelium that is healthy tends to be tenacious, holding the substrate particles together. This is especially true with Stropharia spp. and Oyster mushrooms. (Hericium erinaceus and Morchella spp. are exceptions.) Over-incubation results in a weakened mycelial network whereby the mycelium is incapable of holding various substrate particles together. As mycelial integrity declines, other decomposers are activated. Often, when mixing in new material at this stage, weed fungi proliferate to the decided disadvantage of the selected gourmet species. To the eye, the colony no longer looks like a continuous sheet of mycelium, but becomes spotty in its growth pattern. Soon islands of mycelia become smaller and smaller as they retreat, eventually disappearing altogether. The only recourse is to begin anew, scraping away the now-darkened wood/soil, and replacing it with a new layer of wood chips and/or other organic debris.

When to Inoculate an Outdoor Mushroom Patch

Outdoor beds can be inoculated in early spring to early fall. The key to a mushroom bed is that the mycelium has sufficient time to establish a substantial mycelial mat before the onset of inclement weather conditions. Springtime is generally the best time to inoculate, especially for creating large mushroom patches. As fall approaches, more modestly sized beds should be established, with a correspondingly higher rate of inoculation for faster growth. For most saprophytic species, at least 4 weeks are required to form the mycelial network with the critical mass necessary to survive the winter.

Most woodland species survive wintering temperatures. Temperate woodland mushrooms have evolved protective mechanisms within their cellular network that allow them to tolerate cold temperature extremes. Surface frosts usually do not harm the terrestrially bound mushroom mycelium. As the mycelium decomposes organic matter, heat is released, which benefits subsurface mycelium. Mycelial colonization essentially stops when outdoor temperatures fall below freezing.

Site Location of a Mushroom Patch

A suitable site for a mushroom patch is easy to choose. The best clue is to simply take note of where you have seen mushrooms growing during the rainy season. Or just observe where water traverses after a heavy rain. A gentle slope, bordered by shrubs and other shade-giving plants, is usually ideal. Since saprophytic mushrooms are noncompetitive to neighboring plants, they pose no danger to them. In fact, plants near a mushroom bed often thrive—the result of the increased moisture retention and the release of nutrients into the root zone.

An ideal location for growing mushrooms is in a vegetable, flower, and/or rhododendron garden. Gardens are favored by plentiful watering, and the shade provided by potato, zucchini, and similar broadleaf vegetable plants tend to keep humidity high near the ground. Many gardeners bring in sawdust and wood chips to make pathways between the rows of vegetables. By increasing the breadth of these pathways, or by creating small cul-de-sacs in the midst of the garden, a mushroom bed can be ideally located and maintained.

Other suitable locations are exposed north sides of buildings, and against rock, brick, or cement walls. Walls are usually heat sinks, causing condensation, which provides moisture to the mushroom site as temperature fluctuates from day to night. Protected from winds, these locations have limited loss of water due to evaporation.

Mushrooms love moisture. By locating a mushroom bed where moisture naturally collects, colonization is rapid and more complete, and the need for additional water for fruiting is minimized. The message here: Choose your locations with moisture foremost in mind. Choose shady locations over sunny ones. Choose north-facing slopes rather than south facing. Choose companion plants with broad leaves or canopies that shade the midday sun but allow rain to pass. The difference in results is the difference between a bountiful success or dismal failure.

Giant Oyster mushrooms fruiting from a stump.

Stumps as Platforms for Growing Mushrooms

Stumps are especially suitable for growing gourmet mushrooms. There are few better, or more massive platforms, than the stump. Millions of stumps are all that remain of many forests of the world. In most cases, stumps are seen as having little or no economic potential. These lone tombstones of biodegradable wood fiber offer a unique, new opportunity for the mycologically astute. With selective logging being increasingly practiced, cultivating gourmet and medicinal mushrooms on stumps will be the wave of the future.

The advantage of the stump is not only its sheer mass, but with roots intact, water is continuously being drawn via capillary action. Once mycelium has permeated through wood fiber, the stump’s water-carrying capacity is increased, thus further supporting mycelial growth. Candidates for stump culture must be carefully selected and matched with the appropriate species. A stump partially or fully shaded is obviously better than one in full sunlight. Stumps in ravines are better candidates than those located in the center of a clear-cut area. An uprooted stump is not as good a candidate as a well-rooted one. The presence of mosses, lichens, and/or ferns is a good indicator that the microclimate is conducive to mushroom growth. However, the presence of competitor fungi generally disqualifies a stump as a good candidate. These are some of the many factors that determine the suitability of stumpage.

Cultivating mushrooms on stumps requires forethought. Stumps should be inoculated before the first season of wild mushrooms. With each mushroom season, the air becomes laden with spores, seeking new habitats. The open face of a stump, essentially a wound, is highly susceptible to colonization by wild mushrooms. With the spore cast from wild competitors, the likelihood of introducing your species of choice is greatly reduced. If stumps are not inoculated within several months of being cut, the probability of success decreases. Therefore, old stumps are poor candidates. Even so, years may pass after inoculation before mushrooms form on a stump. But once a colony begins, the same species may predominate for many years.

Large-diameter stumps can harbor many communities of mushrooms. On old-growth or second-growth Douglas fir stumps common to the forests of Washington State, finding several species of mushrooms is not unusual. This natural example of “polyculture”—the simultaneous concurrence of more than one species in a single habitat—should encourage experimentally inclined cultivators. Mushroom landscapes of great complexity could be designed. However, the occurrence of poisonous mushrooms should be expected. Two notable toxic mushrooms frequent stumps: Hypholoma fasciculare (=Naematoloma fasciculare) which causes gastrointestinal upset but usually not death, and Galerina autumnalis, a mushroom that does kill. Because of the similarity in appearance between Flammulina velutipes (Enoki) and Galerina autumnalis, I hesitate to recommend the cultivation of Enoki mushrooms on stumps unless the cultivator is adept at identification. (To learn how to identify mushrooms, please refer to the recommended mushroom field guides listed in Appendix 4.)

Several polypores are especially good candidates for stump cultivation, particularly Grifola frondosa, Maitake, Ganoderma lucidum, Reishi, and its close relatives. As the antiviral and anticancer properties of these mushrooms become better understood, new strategies for the cultivation of medicinal mushrooms will be developed. I envision the establishment of Maitake and Reishi mushroom tree farms wherein stumps are purposely created and selectively inoculated for maximum mushroom growth, interspersed among shade trees. Once these models are perfected, other species can be incorporated in creating a multicanopy medicinal forest.

Drilling and inoculating a stump with plug spawn.

Small-diameter stumps rot faster and produce crops of mushrooms sooner than bigger stumps. However, the smaller stump has a shorter mushroom-producing life span than the older stump. Often with large-diameter stumps, mushroom formation is triggered when competitors are encountered and/or coupled with wet weather conditions. The fastest I know of a stump producing mushrooms from time of inoculation is 8 weeks. In this case, an oak stump was inoculated with plug spawn of Chicken-of-the-Woods, Laetiporus (Polyporus) sulphureus. Notably, the stump face was checkered, with multiple fissures running vertically through the innermost regions of the wood. These fissures trapped water from rainfall and promoted fast mycelial growth. Another technique that improves success rates is to girdle the stump with a chain saw, interrupting direct contact between the root zone and the above-air portion. A local mycological society found that all their inoculated stumps produced which were girdled compared to a small fraction for those that were not. As with the growing of any mushrooms, the speed of colonization is a determining factor in the eventual success or failure of any cultivation project.

For foresters and ecologists, actively inoculating and rotting stumps has several obvious advantages. Rather than allowing a stump to be randomly decomposed, species of economic or ecological significance can be introduced. For instance, a number of Honey mushrooms, belonging to the genus Armillaria, can operate as both saprophytes or parasites. Should clear-cuts become colonized with these deadly, root-rotting species, satellite colonies can be spread to adjacent living trees. Now that burning is increasingly restricted because of air pollution concerns, disease vectors coming from stumpage could present a new as-yet-unmeasured threat to the forest ecosystem.

The Honey mushroom, Armillariella mellea, growing on a fir stump in a rhododendron garden, an ideal locus for creating a mycological landscape.

The advantages of growing on stumps can be summarized as

• Developing a new, environmentally friendly wood products industry.
• Recycling wood debris of little or no economic value.
• Prevention of disease vectors from parasitic fungi.
• The rapid return of wood debris back into a nutritious food for the benefit of other citizens of the forest. Since the food chain is accelerated and enriched, ecosystems are invigorated.

Few studies have been published on recycling stumps with mushrooms. One notable work from Eastern Europe, published by Pagony (1973), describes the cultivation of Oyster mushrooms (Pleurotus ostreatus) on large-diameter poplars with a 100% success rate. Inoculations in the spring resulted in fruitings appearing the ensuing fall, and continued for several years hence. An average of 4 pounds of Oyster mushrooms were harvested over 4 years (i.e., 1 pound/year/stump). Hilber (1982) also reported on the utility of using natural wood (logs and stumps) for growing Oyster mushrooms, and that per cubic meter of elm wood, the yield from one season averaged 17–22 kilograms. A study in France by Anselmi and Deandrea (1979), where poplar and willow stumps were inoculated with spawn of the Oyster mushroom, showed that this mushroom favored wood from newly felled trees, in zones that received speckled sunlight. This study confirmed that Pleurotus ostreatus only attacked deadwood and never became parasitic. Their study supports my opinion (Stamets, 1990) that the purposeful inoculation of stumps can forestall the invasion by parasites like Honey mushrooms of the Armillaria mellea complex. Mushrooms of this group first kill their host and then continue to live saprophytically. A stump with Honey mushrooms can later destroy neighboring living trees. In Washington State, one colony of Honey mushrooms is blamed for destroying thousands of acres of conifers.

Inoculating a stump with the wedge and the spawn disk technique.

Stumps can be inoculated by one of several simple procedures. Plug spawn can be inserted into the open face of each stump. If the stumps are checkered through with cracks, the plugs are best inserted directly into the fissures. Another method is known as the wedge or disk inoculation technique. With a chain saw, a wedge is cut or a shallow disk is sliced from the open face of the stump. The newly cut faces are packed with sawdust spawn. The cut disk is then replaced. By hammering a few nails into the stump, you can assure firm contact between the cut faces. Another method I have developed is to add spores to biodegradable chainsaw oil so that as trees are being cut, the stumps are inoculated. (Patent pending).

Plug spawn of Shiitake. Spirally grooved wooden dowels help the mycelium survive from the concussion of inoculation.

The broadleaf hardwoods are easier to saprophytize with the gourmet and medicinal mushroom species described in this book than the softwood pines. And within the hardwood group, the rapidly growing species such as the alders and poplars decompose more rapidly—and hence give an earlier crop—than the denser hardwoods such as the oaks. However, the denser and more massive stumps sustain colonies of mushrooms for many more years than the quick-to-rot, smaller-diameter tree species. In a colonial graveyard in New York state, a four-foot-diameter oak has consistently produced clusters of Maitake mushrooms, sometimes weighing up to 100 pounds apiece, for more than 20 years! See this image.

Inoculating stumps with strains cloned from native mushrooms is favored over the use of exotic fungi. Spring inoculations give the mycelium the longest possible growing season.

Stump cultivation has tremendous potential. These unexploited resources can become production sites of gourmet and medicinal mushrooms. Although more studies are needed to ascertain the proper matching of species to the wood types, I encourage you to experiment. Only a few minutes are required to inoculate a stump or dead tree. The potential rewards could span a lifetime.

The “soak and strike” method for initiating Shiitake.

Figure 14. Natural culture of Shiitake in the mountains of Japan. (Photographs, both from Mimura, Japan, circa 1915.)

Log Culture

Log culture was developed in Japan and China more than a millennium ago. Even today, thousands of small-scale Shiitake growers use log culture to provide the majority of mushrooms sold to markets. In their backyards and along hillsides, inoculated logs are stacked like cordwood or in fence-like rows. These growers supply local markets, generating a secondary income for their families. Attempts to reproduce this model of Shiitake cultivation in North America and Europe has met with modest success.

The advantage of log culture is that it is a simple and natural method. The disadvantage is that the process is labor-intensive, and slow in comparison to growing mushrooms on sterilized sawdust. Besides Shiitake, many other mushrooms can be grown on logs, including Nameko (Pholiota nameko), all the true Oyster mushrooms (Pleurotus and Hypsizygus spp.), Lion’s Mane (Hericium erinaceus), Wood Ears (Auricularia auricula), Clustered Woodlovers (Hypholoma capnoides and H. sublateritium) and Reishi (Ganoderma lucidum). Since log culture is not technically demanding, anyone can do it. In contrast, growing on sterilized substrates requires specialized skills and involves training in laboratory technique.

Drilling and inoculating plugs into logs.

Once inoculated, the plugs and ends are sealed with cheese wax.

Inoculated logs are stacked and covered with a tarp.

When logs are colonized, Psilocybe azurescens has whitish rhizomorphic mycelium.

Logs are usually cut in the winter or early spring before leafing, when the sapwood is rich in sugars, to a yard in length and 4–10 inches in diameter. The logs, once felled, should be kept off the ground. Ideally inoculations should occur within 2 months of felling, preferably in early spring. (In temperate North America, February and March are ideal.) Logs can be inoculated by a variety of methods. Cultivators generally favor logs that have a higher ratio of sapwood to heartwood. (These logs come from fast-growing tree species like alder, poplar, or cottonwood.) Once inoculated with sawdust or plug spawn, the logs (or billets) are stacked in ricks and after 6 to 12 months, are initiated by heavy watering or soaking. After soaking, the logs are lined up in fence-like rows. Japanese growers have long favored the “soak and strike” method for initiating mushroom formation. Before the advent of plug and sawdust spawn, newly cut logs would be placed near logs already producing Shiitake so that the airborne spores would be broadcast onto them. This method, although not scientific, succeeded for centuries and still is a pretty good method. After a year, logs showing no growth or the growth of competitor fungi, are removed from the production rows.

Gymnopilus spectabilis, the Big Laughing Mushroom, Owaritake, fruiting from a log inoculated with sawdust spawn via the wedge technique.

Oyster mushroom (Pleurotus ostreatus) fruiting on alder logs inoculated via the wedge technique.

Oyster mushroom fruiting from alder logs inoculated via the spawn disk technique.

A wide variety of broadleaf hardwoods are suitable for log culture. Some provide for short-term cultivation while others are more resistant to quick decay. Oaks, and similar dense hardwoods with thick outer barks, are preferred over the rapidly decomposing hardwoods with their paper-thin bark layers. The rapidly decomposing hardwoods like alder and birch are easily damaged by weather fluctuations, especially humidity. Should the bark layer fall from the log, the mycelium has difficulty supporting good mushroom crops or flushes.

Logs are usually pegged, i.e., drilled with holes and inoculated with plug or sawdust spawn. Most logs receive 30 to 50 plugs, which are inserted into evenly spaced holes (4–6 inches apart) arranged longitudinally down the axis of the logs in a diamond pattern. By off-centering the rows of holes in a diamond pattern, the mycelium grows out to become one interconnected macroorganism, after which synchronous fruitings can occur. Once inserted by hand, the plugs are pounded in with a rubber mallet or hammer. The plugged hole is covered with cheese wax or beeswax, usually painted on, to protect the mycelium from insect or weather damage.

Another method calls for the inoculation of logs by packing sawdust spawn into cuts made with a chain saw. A common technique is to cut a V-shaped wedge from a log, pack the wound full of sawdust spawn, and press the wedge of wood back into place. Nailing the wedge back into position assures direct and firm contact. Another variation is to cut logs into 16- to 24-inch sections and sandwich spawn in between.

Sawdust spawn can be used in other ways. The newly cut ends of the logs can be packed with sawdust spawn and capped with aluminum foil or a “sock” to hold the mycelium in place. [San Antonio (1983) named this technique the spawn disk method.] Others prefer cutting wedges from the logs and then repacking the cut wedge back into the log with mycelium sandwiched in between. Others cut the logs in sections, 2 feet in length, and pack the sawdust spawn in between the two sections, which are reattached by any means possible. Most hammer long nails to secure the mini-logs back together.

When logs are buried in sand, subsurface moisture is drawn up into the log, encouraging mushroom formation and discouraging competitor fungi.

For anyone growing outdoors in climates with severe dry spells, or where watering is a problem, logs should be buried with a third to a fourth of their length into sandy ground. The ground moisture will constantly replenish water lost through evaporation, lessening the effect of humidity fluctuation. This method is especially useful for the cultivation of Lion’s Mane, Nameko, Oyster, and Reishi. It is widely used by growers in China. Many cultivators protect their logs from the sun by either locating them under a forest canopy or by rigging up a shade cloth.

Most log cultivators develop their own unique techniques, dictated by successes and failures. Many books on log cultivation have been written, too numerous to list here. Two books on Shiitake log cultivation that I highly recommend for those who wish to study these techniques further are Growing Shiitake Mushrooms in a Continental Climate (second edition) by Mary Kozak and Joe Krawczyk and Shiitake Grower’s Handbook by Paul Przybylowicz and John Donoghue. The methods described in these books can be extrapolated for the cultivation of other gourmet and medicinal mushrooms on logs.

The Stametsian Model for Permaculture with a Mycological Twist.

The Stametsian Model for a Synergistic Mycosphere

Permaculture is a concept pioneered by Australian Bill Mollison and literally is a fusion of “permanent agriculture” and “permanent culture.” His model of biological diversity and complementary agricultural practices promotes a sustainable environment via the interplay of natural ecosystems. Permaculture has gained a huge international following since the publication of his book Permaculture: A Practical Guide for a Sustainable Future. Permaculture has become the mainstay philosophy of the organic movement. Mollison’s vision, which borrows from Masanobu Fukuoka’s “One Straw Revolution,” intelligently combines the factors of site location, recycling of by-products from farming and forest activities, species diversity, and biological succession.

When gourmet and medicinal mushrooms are involved as key organisms in the recycling of agricultural and forest by-products, the biodynamics of permaculture soar to extraordinary levels of productivity. Mushrooms are the missing link in the permaculture model. Not only are mushrooms a protein-rich food source for humans, but the by-products of mushroom cultivation unlock nutrients for other members of the ecological community. The rapid return of nutrients back into the ecosystem boosts the life cycles of plants, animals, insects (bees), and soil microflora. The soil that fungi produce sustains, ultimately, all life. The complex activity of mushroom allies allows habitats to achieve degrees of biological intensity that are absent in fungally impoverished habitats. It is the fungal web that holds habitats together. Environments can best support populations of humans when nutrients are cycled back into the ecosystem using fungi as the link. Scientists are substantiating that mushroom mycelia proliferate when farmers employ the “no-till” method, fertilizing the soil as crop debris is decomposed.

What follows is a short list of the ways mushrooms can participate in permaculture. The numbers are keyed to the numbers in the accompanying illustration: The Stametsian Model for Permaculture with a Mycological Twist.

Oyster mushrooms fruiting from a stump inoculated with sawdust spawn.

Honey bees suckling on the mycelium of Stropharia rugosoannulata.

LaDena Stamets sitting among 5-pound specimens of the King Stropharia, Stropharia rugosoannulata.

Three-pound specimen of King Stropharia.

Mushrooms, in this case Reishi (Ganoderma lucidum), can be grown on logs buried into sawdust or soil.

These are but a few mushroom species that can be incorporated into the permaculture model. Part of a larger, community-based permaculture strategy should also include Mushroom Response Teams (MRTs) which could react quickly to catastrophic natural disasters—such as hurricanes, tornadoes, floods—in the profitable recycling of the enormous debris fields they generate.

Clearly, the use of mushrooms energizes permaculture to a level otherwise not attainable. I hope readers will develop these concepts further. When fungi are incorporated into these models, the ecological health of the whole planet benefits enormously.

The potential for recycling organic wastes via fungi seems unlimited. Surprisingly, many mushrooms thrive on base materials alien to their natural habitat. Although Oyster mushrooms are generally found in the wild on deciduous woods, these mushrooms grow well on many other materials besides hardwoods, including cereal straws, corncobs, seed hulls, coffee wastes, sugarcane bagasse, paper and pulp by-products, and numerous other materials.

Success increases if the base material is first reduced to an optimal structure and moisture—and if heat-treated—before inoculation. The fact that many mushrooms can cross over to other nonnative habitat components gives the cultivator tremendous latitude in designing habitats.

Materials for composing a mushroom substrate are diverse and plentiful. Because fungi decompose plant tissue, most homeowners can use by-products generated from gardening, landscaping, tree pruning, and even building projects. Homeowners who collect and pile debris have a perfect opportunity for growing a variety of gourmet and medicinal mushrooms. If a mushroom of choice is not introduced, a wild species from the natural environment will invade. The probability that one of these invading wild mushrooms would be a gourmet species is remote.

I prefer sawdust and wood debris as primary substrate components. Deciduous woods, especially those that decompose quickly, are best. These fast-rotting woods, being less able to resist disease, accelerate the mushroom life cycle. Alder, cottonwood, and poplar are favored over the more resistant, denser woods such as the oaks, maples, or ironwoods. Once the wood sawdust is gathered, additional materials are added to fortify the substrate. Three additional factors affect the suitability of a mushroom habitat: structural composition, pH, and moisture.

The selection of the substrate components is more critical for growing gourmet mushrooms indoors than for growing outdoors. Commercial cultivators prefer the controlled conditions of indoor cultivation whereas most home cultivators are more attracted to outdoor cultivation, au naturale. Outdoor mushroom beds can be more complex, composed of crude mixtures of components, whereas for indoor cultivation, the uniformity and consistency of the substrate are essential.

A new medicinal food? Oyster mushrooms fruiting from corncobs. Zusman et al. (1997) published evidence that this combination could prevent tumors.

Raw Materials

Most by-products from agriculture and forestry industries can make up a base medium for mushroom culture. This base medium is commonly referred to as the “fruiting substrate.” This primary material is often supplemented with a carbohydrate- and protein-rich additive to enhance yields. Here is a short list of the materials that can be recycled into mushroom production.

Suitable Wood Types: Candidate Tree Species

A vast variety of woods can be used for growing gourmet and medicinal mushrooms. Generally speaking, the hardwoods are more useful than the softwoods. Several wood types may not perform by themselves but when combined with other more suitable woods—and boosted with a nutritional supplement—will give rise to commercially viable crops. Recommended hardwoods are alders, birches, hornbeams, chestnuts, chinkapins, beeches, ashes, larches, sweetgums, tanoaks, cottonwoods, willows, ironwoods, walnuts, sweetgums, elms, and similar woods. Suggested softwoods are Douglas firs and hemlocks. Most other pines (ponderosa, lodgepole), cedars, and redwood are not easily degraded by mushroom mycelium. Aromatic hardwoods, such as eucalyptus, were once not recommended because some people became ill from eating its otherwise edible mushrooms (Arora, 1990). We now know that eucalyptus species are excellent candidates, and that the reports of ill effects were likely isolated cases. Cedars and redwoods are also not recommended as they decompose slowly due to their anti-rotting compounds, and hence stifle mushroom growth. All woods eventually succumb to fungal decomposition.

Woods other than those listed may prove to be satisfactory. Hence, experimentation is strongly encouraged. I find that the fast-growing, rapidly decomposing hardwoods are generally the best because they have greater ratios of starch-enriched sapwood to heartwood. These sugars encourage rapid initial growth, resulting in full colonization in a short period of time. The key to successful cultivation is to match the skills of the cultivator with the right strain on the proper substrate under ideal environmental conditions.

For outdoor log culture, disease-free logs should be selected from the forest in the winter or early spring. If you use sawdust and chips for indoor or outdoor cultivation, freshness counts—or else competitors may have already taken hold. Lumber mills, pulp mills, furniture manufacturers, and many other wood product companies generate waste usable to the mushroom cultivator. However, those industries that run mixed woods and do not separate their sawdust into identifiable piles, are not recommended as substrate suppliers. Cultivators face enough problems in their struggle to understand the different yields of each crop cycle. Hence, mixed wood sources are best avoided, if possible.

Red alder (Alnus rubra) is a “weed tree” in western Washington State of North America. Like poplars and cottonwoods, its penchant for valleys, wetlands, and open habitats encourages a prodigious growth rate. Many of these trees are common along roads where they foul telephone and electrical lines. A whole industry is dedicated to rendering these trees into chips, a fortuitous situation for mushroom cultivators. A matrix of smaller and larger particles can be combined to create an ideal habitat for mycelium. The smaller particles stimulate quick growth (“leap-off”). The larger particles encourage the mycelium to form thick, cord-like strands, called rhizomorphs, which forcibly penetrate through and between the cells. The larger chips become nutritional bases, or fruiting platforms, giving rise to super-large mushrooms. The larger chips also create air spaces, increasing respiration (Royse, 2000). This concept has been an overriding influence, steering my methods, and has resulted, for instance, in the large 5-pound specimens of Stropharia rugosoannulata, the Garden Giant, that is pictured in this book. A simple 50:50 mixture (by volume) of sawdust and chips, of varying particle sizes, provides the best structure for the mushroom habitat. The substrate matrix concept will be explored in greater detail later on.

City and county utility companies are ready sources for wood chips. However, cultivators should avoid wood chips originating from trees along busy roadways. Automobile exhaust and leachate from the oil-based asphalt contaminate the surrounding soil with toxins, including lead and aluminum. Metals can be concentrated by the mushroom mycelium and transferred to mushrooms. Wood chips from county roads with little traffic are less prone to this heavy metal contamination. Obtaining sawdust and chips from large-diameter trees largely circumvents this problem. Sawmills and pulp chip companies provide the cleanest source of wood debris for substrate preparation.

Currently, the heavy metal concentrations taken up by most mushrooms found in forests of western North America are well below the standards set by the United States government for fish, for instance. However, air pollution is an increasing threat, and mushrooms collected near industrialized centers will have heavier concentrations of heavy metals. Analyses of mushrooms grown in China, California, and Washington State revealed that the Chinese mushrooms had the greatest aluminum, mercury, and lead concentrations, with Californian mushrooms next, and mushrooms grown in the less industrialized Olympic Peninsula of Washington had the least. With the phasing out of lead-based gasoline and the implementation of tougher environmental restrictions, pollution of wood sources may be ameliorated. (For more information on the concentration of metals and toxins, and their potential significance, consult Stijve, 1974, 1976, and 1992.) Many environmental service companies will analyze your product for a nominal fee, usually between US $50 and $125. If an analysis shows unusually high levels, the same specimens should be sent to an unrelated laboratory for confirmation. Please consult your Department of Agriculture, county extension agent, or comparable agency for any applicable threshold requirements.

Cereal Straws

For the cultivation of Oyster mushrooms, cereal straws rank as the most usable base material. Wheat, rye, oat, and rice straw perform the best. Of the straws, I prefer wheat. Inexpensive, readily available, preserving well under dry storage conditions, wheat straw admits few competitors. Furthermore, wheat straw has a nearly ideal shaft diameter that selectively favors the filamentous cells of Oyster mushrooms. Chopped into 1- to 4-inch lengths, the wheat straw needs only to be pasteurized by any one of several methods. The approach most easily used by home cultivators is to submerge the chopped straw in hot water (160°F, 71°C) for 1 to 2 hours, drain, and inoculate. First, fill a metal barrel with hot tap water and place a propane burner underneath. (Drums should be food grade quality. Do not use those that have stored chemicals.) A second method calls for the laying of straw onto a cement slab or plastic sheeting to a depth of no more than 24 inches. The straw is wetted and turned for 2 to 4 days, and then loaded into a highly insulated box or room. Steam is introduced, heating the mass to 160°F (71°C) for 2 to 4 hours. (See Chapter 18 for these methods.)

The semi-selectivity of wheat straw, especially after pasteurization, gives the cultivator a 2-week window of opportunity to establish the gourmet mushroom mycelium. Wheat straw is one of the most forgiving substrates with which to work. Outdoor inoculations of pasteurized wheat straw with grain spawn, even when the inoculations take place in the open air, have a surprisingly high rate of success for home cultivators.

Rye straw is similar to wheat, but coarser. Oat and rice straw are finer than both wheat and rye. The final structure of the substrate depends upon the diameter and the length of each straw shaft. Coarser straws result in a looser substrate, whereas finer straws provide a denser or “closed” substrate. A cubic foot of wetted straw should weigh around 20–25 pounds. Substrates with lower densities tend to perform poorly. The cultivator must design a substrate that allows air exchange all the way to the core. Substrate dynamics are determined by a combination of all these variables.

Oyster mushrooms growing from my previous book, The Mushroom Cultivator.

Paper Products: Newspaper, Cardboard, Books

Using paper products as a substrate base is particularly attractive to those wishing to grow mushrooms where sawdust supplies are limited, such as on islands and in desert communities. Paper products are made of lignin-cellulose fibers from pulped wood, and therefore support most of the wood-decomposing mushrooms described in this book. In recent years, most printing companies have switched to soybean-based inks, reducing or almost eliminating toxic residues. Since many large newspapers are recycling, data on toxin residues is readily available. (If the data cannot be validated, or are outdated, the use of such newsprint is not recommended.) Since the use of processed wood fiber may disqualify a grower for state organic certification, U.S. cultivators should check with the Organic Certification Director at the State Department of Agriculture before venturing into the commercial cultivation of gourmet mushrooms on paper-based waste products. If these preconditions can be satisfied, the would-be cultivator can tap into an enormous stream of materials suitable for substrate composition.

Corncobs and Cornstalks

Corncobs (sans kernels) and cornstalks are conveniently structured for the rapid permeation of mycelium. Their cell walls and seed cavities provide a uniquely attractive environment for mycelium. Although whole corncobs can be used directly, grinding corncobs to 1–3 inches using hammer-mill type chipper-shredders creates more uniform-sized particles. After moistening, the corn roughage can be cooked for 2 to 4 hours at 160–180°F (71–82°C) to achieve pasteurization. If the kernels are still on the cob, sterilization may be necessary. Cornstalks, having a lower nutritional content, are less likely to become contaminated.

Coffee and Banana Plants

In the subtropical and tropical regions of Central and South America, the abundance of coffee and banana leaves has spurred mycologists to examine their usefulness in growing gourmet mushrooms. The difficulty in selecting any single plant material from warm, humid regions is the speed of natural decomposition due to the activity of competitors. The combination of high humidity and heat accelerates decomposition of everything biodegradable. Leaves must be dried, shredded, and stored in a manner not to encourage composting. Once weed fungi, especially black and green molds, begin to proliferate the suitability of these base materials is jeopardized. Mushrooms demonstrating commercial yield efficiencies on banana and coffee pulp are warm-weather strains of Oyster mushrooms, particularly Pleurotus citrinopileatus, Pleurotus cystidiosus, Pleurotus djamor, Pleurotus ostreatus, and Pleurotus pulmonarius. Reishi mushrooms (Ganoderma lucidum) grow well, and I suspect many other Polypores would also. For more information on the cultivation of Oyster mushrooms on coffee waste, please refer to Martinez-Carrera (1985, 1987, 1988) and Thielke (1989).

Sugarcane Bagasse

Sugarcane bagasse is the major waste product recovered from sugarcane harvesting and processing. Widely used in Hawaii and the Philippines by Oyster growers, sugarcane bagasse needs only pasteurization for cultivating Oyster mushrooms. Some Shiitake strains will produce on sugarcane residue, but yield efficiencies are low compared to wood-based substrates. Since the residual sugar stimulates mycelial growth and is a known trigger to fruiting, sugarcane residues are good complements to wood-based substrates.

Seed Hulls

Seed hulls, particularly cottonseed hulls, are perfect for their particle size and their ability to retain water. Their readily available form reduces the material handling costs. Buffered with 5–7% calcium sulfate and calcium carbonate, cottonseed hulls simply need wetting, pasteurization, and inoculation. Cottonseed hulls, on a dry weight basis, are richer in nitrogen than most cereal straws. Many Button cultivators consider cottonseed hulls a supplement to their manure-based composts. On unamended seed hulls, Oyster and Paddy Straw are the best mushrooms to grow.

Peanut shells have had little or no value except to mushroom growers. Peanut hulls are rich in oils and starch that stimulate mushroom growth. The shells must be chipped into ¼- to ¾-inch pieces, wetted, and pasteurized for several hours. Because peanut shells form subterraneously and are in ground contact, they should be thoroughly washed before pasteurization. Sterilization may be required if pasteurization is insufficient. The addition of 5% gypsum (calcium sulfate) helps keep the substrate loose and aerated. Oyster mushrooms, in particular, thrive on this material.

Soybean Roughage (Okara)

Okara is the main by-product of tofu and tempeh production. Essentially the extracted roughage of boiled soybean mash, Okara is perfectly suited for quick colonization by a wide variety of mushrooms, from the Pleurotus sp. to Ganoderma lucidum, even Morels. Several companies currently use Okara for generating mycelium for extraction and/or for producing flavorings.

All of the above-mentioned materials can be used to construct a base for mushroom production, outdoors or indoors. A more expansive list could include every primary by-product from agricultural or forestry practices. To the imaginative cultivator, the resources seem almost limitless.

Supplements

Supplementing the substrate can boost yields. A wide variety of protein-rich (nitrogenous) materials can be used to enhance the base substrate. Many of these are grains or their derivatives, like rice, wheat or oat brans, ground corn, etc. Many growers use grape pumice from wineries and spent barley from breweries as supplements. Supplementing a substrate, such as straw or sawdust, changes the number and the type of organisms that can be supported. Most of the raw materials used for growing the mushrooms listed in this book favor mushroom mycelium and are nitrogen-poor. Semi-selectivity is lost after nitrogen supplements are added, but ultimately mushroom yields improve. Therefore, when supplements are used, extra care is required to discourage contamination and insure success. Here good hygiene and good flow patterns to, from, and within the growing rooms are crucial. Supplementation of outdoor beds risks competition from contaminants and insects.

If you are supplementing a substrate, the sterilization cycle should be prolonged. Sterilization must be extended from 2 hours for plain sawdust at 15 psi (pounds per square inch) to 4 hours for the same sawdust supplemented with 20% rice bran.

Supplemented sawdust, straw, and compost substrates undergo thermogenesis, a spontaneous temperature increase as the mycelium and other organisms begin growing. If this naturally occurring biological combustion is not held in check, a plethora of molds awaken as the substrate temperature approaches 100°F (38°C). Below this threshold level, these organisms remain dormant, soon being consumed by the mushroom mycelium. Although true sterilization has not been achieved, full colonization is often successful because the cultivator offsets the upward spiral of temperature. Simply spacing spawn bags or jars apart from one another, and lowering spawn room temperatures as thermogenesis begins, can stop this catalytic climb from starting. For many of the gourmet wood decomposers, a temperature plateau of 75° to 85°F (24° to 29°C) is ideal.

The following supplements can be added at various percentages of total dry mass of the bulk substrate to enhance yields. Please refer to Appendix 5 for their nutritional analyses.

The nutritional composition of these supplements and hundreds of others are listed in Appendix 5. If you are using rice bran as a reference standard, the substitution of other supplements should be added according to their relative protein and nitrogen contents. For instance, rice bran is approximately 12.5% protein and 2% nitrogen. If soybean meal is substituted for rice bran, with its 44% protein and 7% nitrogen content, the cultivator should add roughly ¼ as much to the same supplemented sawdust formula. Until performance is established, the cultivator is better off erring on the conservative side than risking oversupplementation.

A steady supply of supplements can be cheaply obtained by recycling bakery waste, especially stale breads. A number of companies transform bakery by-products into a pelletized cattle feed, which also works well as inexpensive substitutes for many of the additives listed above.

Structure of the Habitat

Whichever materials are chosen for making up the substrate base, particular attention must be given to structure. Sawdust is uniform in particle size but, by itself, is not ideal for growing mushrooms outdoors. Fine sawdust is “closed,” which means the particle size is so small that air spaces are soon lost due to compression. Closed substrates tend to become anaerobic and encourage weed fungi to grow.

Wood shavings have the opposite problem of fine sawdust. They are too fluffy. The curls have large spaces between the wood fibers. Mycelium will grow on shavings, but too much cellular energy is needed to generate chains of cells to bridge the gaps between one wood curl and the next. The result is a highly dispersed, cushion-like substrate capable of supporting vegetative mycelium, but incapable of generating mushrooms since substrate mass lacks density.

The ideal substrate structure is a mix of fine and large particles. Fine sawdust particles encourage mycelia to grow quickly. Interspersed throughout the fine sawdust should be larger wood chips (1–4 inches), which are used as concentrated islands of nutrition. Mycelium running through sawdust is often wispy in form until it encounters larger wood chips, whereupon the mycelium changes and becomes highly aggressive and rhizomorphic as it penetrates through the denser woody tissue. The structure of the substrate affects the design of the mycelium network as it is projected. From these larger island-like particles, abundant primordia form and can enlarge into mushrooms of great mass.

For a good analogy for this phenomenon, think of a campfire or a wood stove. When you add sawdust to a fire, there is a flare of activity that soon subsides as the fuel burns out. When you add logs or chunks of wood, the fire is sustained over the long term. Mycelium behaves in much the same fashion. Larger chips sustain long-term growth.

Although homogeneity in particle size is important at all stages leading up to and through spawn generation, the fruitbody formation period benefits from having a complex mosaic of substrate components. In many cases, there is a direct relationship between the complexity of habitat structure and health of the resulting mushroom bed. Optimizing the structure of a substrate is essential for good yields. If fine sawdust and wood chips (in the 1- to 4-inch range) are available, mixing 2 units of sawdust to every 1 unit of wood chips (by volume) provides a good platform for mycelial colonization. Garden shredders are useful in reducing piles of debris into the 1- to 4-inch chips. Many times roadside maintenance crews trim and chip brush from along roads and will give them to you for free.

A good substrate can be made from a mix of woody debris, chopped corncobs and cornstalks, stalks of garden vegetables, and vines of berries or grapes. When the base components are disproportionately too large or small, without connective particles, then colonization by the mushroom mycelium is hindered. The goal is create a substrate of complex particle size and structure, with air pockets and dense pockets of nutrition.

Mushroom strains vary in their ability to convert substrate materials into mushrooms as measured by a simple formula known as the “Biological Efficiency (B.E.) Formula” (originally developed by the White Button mushroom industry). This formula states that

• 1 pound of fresh mushrooms grown from 1 pound of dry substrate is 100% biological efficiency.

Considering that the host substrate is moistened to approximately 75% water content and that most mushrooms have a 90% water content at harvest, 100% B.E. is also equivalent to

• Growing 1 pound of fresh mushrooms for every 4 pounds of moist substrate, a 25% conversion of wet substrate mass to fresh mushrooms, or
• Achieving a 10% conversion of dry substrate mass into dry mushrooms.

Many of the techniques described in this book will give yields substantially higher than 100% B.E. Up to 50% conversion of wet substrate mass into harvestable mushrooms is possible. (I have succeeded in obtaining such yields with sets of Oyster, Shiitake, and Lion’s Mane. Although 250% B.E. is exceptional, a good grower should operate within the 75–125% range.) When you consider the innate power of the mushroom mycelium to transform waste products into highly marketable delicacies, it is understandable why scientists, entrepreneurs, and ecologists are awestruck by the prospects of recycling with mushrooms.

Superior yields can be attained by carefully following the techniques outlined in this book, paying strict attention to detail, and matching these techniques with the right strain. The best way to improve yields is simply to increase the spawn rate. Often the cultivator’s best strategy is not to seek the highest overall yield. The first, second, and third crops (or flushes) are usually the best, with each successive flush decreasing. For indoor cultivators, who are concerned with optimizing yield and crop rotation from each growing room, maximizing yield indoors may incur unacceptable risks. For instance, as the mycelium declines in vigor after several flushes, contaminants flourish. Future runs are quickly imperiled.

Diagram showing comparison of composting raw materials versus sequencing with mushroom mycelia.

If you are growing on sterilized sawdust, I recommend removing the blocks after the third flush to a specially constructed, four-sided, open-air, netted growing room. This overflow or “yield recapture” environment is simply fitted with an overhead nozzle misting system. Natural air currents provide plenty of circulation. These recapture buildings give bonus crops and require minimum maintenance. Growers in Georgia and Louisiana have perfect climates for this alternative. Subtropical regions of Asia are similarly well suited. (For more information, see Appendix 1.)

Biological efficiency depends upon the stage of mushrooms at harvest. Young mushrooms (“buttons”) are generally more delectable and store better. Yet if the entire crop is picked as buttons, a substantial loss in yield potential (B.E.) occurs. Mature mushrooms, on the other hand, may give the cultivator maximum biological efficiency, but also a crop with a very short shelf life and limited marketability.

Each species passes through an ideal stage for harvesting as it matures. Near maturity features are transformed through the reproportionment of cells without any substantial increase in the total weight of the mushroom. This is when the mushroom margins are decurved (pointing downwards) or slightly incurved, and well before spore generation peaks. Over time, cultivators learn the ideal stage for harvest.

As biological efficiency of mushroom production increases, the balance of by-products shifts. After composting the residual substrate, the net nitrogen appears to increase. In fact, overall mass is reduced during composting from loss of carbon-rich gases, especially CO₂, and proportionately affects the C:N ratio.

Chart showing comparison of by-products generated by Oyster (Pleurotus ostreatus) mycelium’s decomposition of wheat straw. (Adapted from Zadrazil, 1976.)

Lillian Stamets holding bag of commercial Agaricus brunnescens spawn.

Spawn is any form of mycelium that can be dispersed and mixed into a substrate. For most would-be cultivators, the easiest way to grow mushrooms is to buy spawn from a company and mix (inoculate) it into a substrate. Spawn can be purchased in a variety of forms. The most common forms are grain or sawdust spawn. Grain spawn is typically used by commercial cultivators to inoculate sterilized or pasteurized substrates. The White Button industry traditionally depends on highly specialized companies, often family-owned, which have made and sold spawn for generations.

Most amateurs prefer buying spawn because they believe it is easier than generating their own. This is not necessarily the case. Because spawn is a living organism, it exists precariously. Spawn remains in a healthy state for a very limited period of time, usually for no more than 2 months. Even under refrigeration, a noticeable decline in viability occurs. After this “honeymoon” period, spawn simply over matures for lack of new food to digest. The acids, enzymes, and other waste products secreted by the mushroom mycelium become self-stifling. As the viability of the spawn declines, predator fungi and bacteria exploit the rapidly failing health of the mycelium. Spawn, healthy at 4 weeks, becomes diseased at 8 weeks. A mycelial malaise seizes the spawn, slowing its growth once sown onto new substrates, and lowering yields. The most common diseases of spawn are competitor molds, bacteria, and viruses. Many of these diseases are only noticeable to experienced cultivators.

For the casual grower, buying commercial spawn is probably the best option. Customers of commercial spawn purveyors should demand: the date of inoculation, a guarantee of spawn purity, the success rate of other clients using the spawn, and the attrition rate due to shipping. Spawn shipped long distances often arrives in a state very different from its original condition. The result can be a customer relations nightmare. I believe the wisest course is for commercial mushroom growers to generate their own spawn. The advantages of making your own spawn are

• Quality control: With the variable of shipping removed, spawn quality is better assured. The constant jostling breaks cells and wounds the spawn.
• Proprietary strain development: Cultivators can develop their own proprietary strains. The strain is the most important key to success. All other factors pale in comparison.
• Reduction of an expense: The cost of generating your own spawn is a mere fraction of the price of purchasing it. Rather than using a spawn rate of only 3–6% of the mass of the to-be-inoculated substrate, the cultivator can afford to use 10–12+% spawning rates.
• Increase the speed of colonization: With higher spawning rates, the window of opportunity for contaminants is significantly narrowed and yields are enhanced. Using the spawn as the vehicle of supplementation is far better than trying to boost the nutritional base of the substrate prior to inoculation.
• Elimination of an excuse for failure: When a production run goes awry, the favorite excuse is to blame the spawn producer, whether at fault or not. By generating your own spawn, you assume full responsibility. This forces owners to scrutinize the in-house procedures that led to crop failure. Thus cultivators who generate their own spawn tend to climb the learning curve faster than those who do not. They have only themselves to blame for failure.
• Insight into the mushroom life cycle: Mycelium has natural limits for growth. If the spawn is “overexpanded,” i.e., it has been transferred too many times, vitality declines. Spawn in this condition grows slowly and often shows symptoms of genetic decline. A spawn producer can use his/her spawn at the peak of its vitality. Those who buy spawn from afar cannot.

When a collector finds mushrooms in the wild, the encounter is a mere coincidence, a “snapshot” in time of a far vaster process. The mushroom life cycle remains largely invisible to most mushroom hunters; not so to cultivators. The mushroom cultivator follows the path of the mushroom life cycle. Only at the completion of the mushroom life cycle, which may span weeks or months, do mushrooms appear, and then they occur but for a few days. The stages leading up to their appearance remain fascinating even to the most sagacious mycologists.

For mushrooms to survive in our highly competitive world, where legions of other fungi and bacteria seek common ecological niches, millions of spores are produced per mushroom. A small mushroom, only 4 inches across can produce more than a million spores! With the larger agarics, the numbers become astronomical. Since mushrooms reproduce through spores, the success of the mushroom life cycle depends upon the production of these spore-producing organs.

Each spore that is released possesses one-half of the genetic material necessary for the propagation of the species. Upon germination, a filamentous cell called a hypha, extends. Hyphae continue to reproduce mitotically. Two spores, if compatible, come together, fuse, and combine genetic material. The resulting mycelium is then described as being binucleate and dikaryotic. After this union of genetic material, the dikaryotic mycelium accelerates in its growth, again reproducing mitotically. Mated mycelium characteristically grows faster than unmated mycelium arising from single spores.

The Mushroom Life Cycle

The mating of compatible spores is genetically determined. Most of the gourmet species are governed by two incompatibility factors (A and B). As a result, only subsets of spores are able to combine with one another. When spores germinate, several strains are produced. Incompatible strains grow away from each other, establishing their own territorial domains. In this sense, spores from one mushroom can actually compete with one another for the same ecological niche. When compatible spores come together and mate, a much more vigorous form of mycelium fans out.

Each mushroom is like an island. From each center, populations of spores decrease with distance. When spores germinate, the mycelium grows radially, away from the site of origin. Waves of mycelia emanate outwards, and can cover thousands of acres. Overlaying mosaics of mycelium become a complex biological plateau supporting a wide variety of other organisms. Spores, taken up by the wind, or carried by insects and mammals, are dispersed to habitats well distant from the parent mushroom. By coincidence, different varieties of the same species meet and exchange genetic material. In the ever-changing ecological landscape, new varieties are favorably selected for and survive. The driving force of diversity is critical for successful adaptation to environments in flux.

Enzymes and acids are secreted by the mushroom mycelium into the surrounding environment, breaking down lignin-cellulose complexes into simpler compounds. The mushroom mycelium absorbs these reduced organic molecules as nutrients directly through its cell walls. After one mushroom species has run its course, the partially decomposed substrate becomes available to secondary and tertiary saprophytes who reduce it further. Ultimately, a rich soil is created for the benefit of plants and other organisms. (See analysis found here.)

As the mycelium expands, a web of cells is formed, collectively called the mycelial network. The arrangement of these cells is designed to optimally capture an ecological niche. Species differ in the manner by which the mycelial mat is projected. Initially, Morel mycelium throws a thinly articulated mycelial network. (Morel mycelium is the fastest growing of any mushroom I have seen.) Once a substantial territorial domain has been overrun, side branching of the mycelium occurs, resulting in a thickening of the mycelial mat.

Sclerotia of Teonancactl, Psilocybe mexicana.

Sclerotia of Zhu Ling, known to North Americans as the Umbrella Polypore, Polyporus umbellatus.

With the approach of winter, the mycelial mat retreats to survive in specific sites. At this time, many mushrooms, both gilled and nongilled, produce sclerotia. Sclerotia are a resting phase in the mushroom life cycle. Sclerotia resemble a hardened tuber, wood-like in texture. (See below and here.) While in this dormant state, the mushroom species can survive inclement weather conditions like drought, fire, flooding, or other natural catastrophes. In the spring, the sclerotia swell with water and soften. Directly from the sclerotia, mushrooms emerge. Morels are the best-known mushrooms that arise from sclerotia. (See this illustration of the Morel lifecycle.) By the time you find a mature Morel, the sclerotia from which it came will have disappeared.

Sclerotia of King Tuber Oyster, Pleurotus tuberregium.

Scanning electron micrograph of the mycelium.

Most saprophytic mushrooms produce a thick mycelial mat after spore germination. These types of mycelial mats are characterized by many crossovers between the hyphae. When two spores come together and mate, the downstream mycelium produces bridges between the cells, called clamp connections. Clamp connections are especially useful for cultivators who want to determine whether or not they have mated mycelium. Mycelium arising from a single spore lacks clamp connections entirely, and is incapable of producing fertile mushrooms.

As the mycelial network extends, several by-products are produced. Besides heat, carbon dioxide is being generated in enormous quantities. One study (Zadrazil, 1976) showed that nearly 50% of the carbon base in wheat straw is liberated as gaseous carbon dioxide in the course of its decomposition by Oyster mushrooms! Ten percent was converted into dried mushrooms; 20% was converted to proteins. Other by-products include a variety of volatile alcohols, ethylenes, and other gases.

While growing through a substrate, the mycelium is growing vegetatively. The vegetative state represents the longest phase in the mushroom life cycle. The substrate will continue to be colonized until physical boundaries prevent further growth or a biological competitor is encountered. When vegetative colonization ceases, the mycelium enters into temporary stasis. Heat and carbon dioxide evolution decline, and nutrients are amassed within the storage vestibules of the cells. This resting period is usually short-lived before entering into the next phase.

From the natural decline in temperature within the host substrate, as well as in response to environmental stimuli (water and humidity, light, drop in temperature, reduction in carbon dioxide, etc.), the mushroom mycelium is triggered into mushroom production. The mechanism responsible for this sudden shift from active colonization to mushroom formation is unknown, often being referred to as a “biological switch.” (Some believe fruiting is triggered when food sources are consumed; I believe it is more a function of the maturity of the mycelial mat.) The mosaic of mycelium, until now homogeneously arranged, coalesces into increasingly dense clusters. Shortly thereafter—literally minutes with some species—these hyphal aggregates form into young primordia. In quick succession, the first discernible differentiation of the cap can be seen.

The mycelium clusters into dense circular colonies.

A miniature mushroom (primordium) emerges from the mycelial plateau.

The period of primordia formation is one of the most critical phases in the mushroom cultivation process. Both mycelium and cultivator must operate as a highly coordinated team for maximum efficiency. Bear in mind that it is the mycelium that yields the crop; the cultivator is merely a custodian. The duration for primordia formation can be as short as 2 days as long as 14. If managed properly, the microscopic landscape, the mycosphere, will give rise to an even, high-density population of rapidly forming primordia. Visible to the naked eye, the mycelium’s surface is punctuated with a latticework of valleys and ridges upon which moisture droplets continually form, rest, and evaporate. In the growing room, this period corresponds to 98–100% rH, or a condensing fog. Even in a fog, air currents have an evaporative effect, drawing moisture to the surface layer. The careful management of this mycosphere, with high oxygen, wicking, evaporation, and moisture replenishment combined with the effect of other environmental stimuli, results in a crescendo of primordia formation. Cultivators call these environmental stimuli collectively the initiation strategy.

Primordia, once formed, may rest for weeks, depending upon the species and the prevailing environment. In most cases, the primordia mature rapidly. Rhizomorphs, braided strands of large-diameter hyphae, feed the burgeoning primordia through cytoplasm streaming. The cells become multinucleate, accumulating genetic material. Walls, or septae, form, separating the nuclei, and the cells expand, resulting in an explosive generation of mushroom tissue.

As the mushroom enlarges, differentiation of familiar features occurs. The cap, stem, veil, and gills emerge. The cap functions much like an umbrella, safeguarding the spore-producing gills from wind and rain. Many mushrooms grow towards light. A study by Badham (1985) showed that with some mushroom species (i.e., Psilocybe cubensis), cap orientation is foremost affected by the direction of air currents, then by light, and finally by gravity. Beneath the cap, the gill plates radiate outwards from a centralized stem like spokes on a wheel.

Scanning electron micrograph of young basidium.

As the basidia mature, sterigmata project from the apex.

Over the surface of the gills, an evenly dispersed population of spore-producing cells, called basidia, emerges. The basidia arise from a genetically rich, dense surface layer on the gill called the hymenium. The gill trama is nestled between the two hymenial layers and is composed of larger interwoven cells, which act as channels for feeding the hymenial layers with nutrients. When the mushrooms are young, few basidia have matured to the stage of spore release. As the mushrooms emerge, increasingly more and more basidia mature. The basidia are club-shaped, typically with four “arms” forming at their apices. These arms, the sterigmata, project upwards, elongating. In time, each tip swells to form a small globular cavity that eventually becomes a spore. (See this image.)

Initially, the young basidia contain two haploid, sexually paired nuclei. They fuse, in a process known as karyogamy, to form one diploid nucleus, containing a full complement of chromosomes. Immediately thereafter, meiosis, or reduction division, occurs resulting in four haploid nuclei. The haploid nuclei are elastic in form, squeezing up the sterigmata to be deposited in their continually swelling tips. Once they are residing in the newly forming spore cavity, the spore casing enlarges. Each spore is attached to the end of each sterigma by a nipple-like protuberance, called the sterigmal appendage. With many species, the opposite end of the spore is dimpled with a germ pore. (See image here.)

At each tip of the sterigmata, a spore cavity forms.

Populations of basidia evenly emerge from the gill plane.

A fully mature basidium. Note germ pores at open ends of spores.

Two-spored basidium. Comparatively few mushrooms have two-spored basidia; most are four spored.

Scanning electron micrograph showing cross-section of gills.

Cheilocystidia as a band on edge of gill.

Close-up of cheilocystidia.

Pleurocystidia and basidia on surface of gill.

The four spores of the basidia emerge diametrically opposite one another. This arrangement assures the highly viscous spores do not touch. Should a young spore come into contact with another before their outer shells harden, they fuse and development is arrested. The spores become pigmented at maturity and are released simultaneously in sets of paired opposites.

The method of spore ejection has been a subject of much study and yet still remains largely a mystery. At the junction between the spore and the basidium’s sterigma, an oily gas bubble forms and inflates. This bubble swells to capacity, explodes, ejecting spores with astonishing force. A recent study (Money, 1998) determined that the basidia shoot spores (ballistospores) with a force equal to 25,000 g’s, 10,000 times more than space shuttle astronauts experience when escaping the earth’s gravitational pull to achieve orbit! Soon thereafter, the remaining pair of spores is released. After ejaculation, the basidium collapses, making way for neighboring basidia, until now dormant, to enlarge. Successions of basidia mature, in ever-increasing quantities, until peaking at the time of mushroom maturity. The well-organized manner by which populations of basidia emerge from the plane of the gill optimizes the efficiency of spore dispersal. After peak spore production, spores cover the gill face several layers deep, hiding the very cells from which they arose. With a Stropharia, this stage would correspond to a mushroom whose gills had become dark purple brown and whose cap had flattened. Spore release at this stage actually declines as the battery of basidia had been largely exhausted and/or because the basidia are rendered dysfunctional by the sea of overlying spores.

Sterile or nonspore-producing cells that adorn the gills are called cystidia. Cystidia on the edge of the gills are called cheilocystidia, while cystidia on the interior surface are called pleurocystidia. (See images here.) The cystidia appear to help the basidia in their development. The extensive surface areas of the cheilocystidia cause the humidity between the gills to rise, thus preserving the hospitable moist microclimate necessary for spore maturity. Typically, the pleurocystidia project well beyond the surface plane of basidia, and in doing, keep the gills from contacting one another. Should the gills touch, spore dispersal is greatly hampered. As the mushrooms mature, cystidia swell with metabolic waste products. Often an oily droplet forms at their tips. The constant evaporation from these large reservoirs of metabolites is an effective way of purging waste by-products and elevating humidity. Species characteristically having pleurocystidia often have a high number of gills per millimeter of radial arc. In other words: more gills, more spores. The survival of the species is better assured.

Once spores have been discharged, the life cycle has come full circle. Mature mushrooms become a feasting site for small mammals (rodents such as squirrels, mice, etc.), large mammals (deer, elk, bear, humans), insects, gastropods (snails), bacteria, and other fungi. From this onslaught, the mushroom quickly decomposes. In due course, spores not transmitted into the air are carried to new ecological niches via these predators.

Mycelium characteristic of Pleurotus cystidiosus and allies, species possessing both a sexual and asexual life cycle. Black droplet structures contain hundreds of spores.

Many mushrooms have alternative, asexual life cycles. Asexual spores are produced much in the same manner as mold spores—on microscopic tree-like structures called conidiophores. Or, spores can form embedded within the mycelial network. Oidia, chlamydospores, and coremia are some examples of asexual reproduction. In culture, these forms appear as “contaminants,” confusing many cultivators. An excellent example is the Abalone Mushroom, Pleurotus cystidiosus and allies. (See above.) The advantage of asexual reproduction is it is not as biologically taxing as the process of mushroom formation. Asexual reproduction disperses spores under a broader range of conditions required than the rather stringent conditions for mushroom formation. In essence, asexual expressions represent shortcuts in the mushroom life cycle. Asexual spores usually regenerate into vigorously growing mycelium.

A cultivator’s role is to assist the mycelium as it progresses through the life cycle by favorably controlling a multitude of variables. The cultivator seeks maximum mushroom production; the mycelium’s goal is the release of the maximum number of spores through the formation of mushrooms. Both join in a biological partnership. But first, a strain from the wild must be captured. To do so, the cultivator must become skilled at sterile technique. And to be successful at sterile technique requires a basic understanding of the vectors of contamination.

Agaricus blazei, the Almond Portobello or Himematsutake mushroom. As the basidia mature, the gills darken with spores. New gill tissue is generated nearest to the stem.

Cultivating mushroom mycelium in a laboratory is tantamount to not cultivating contaminants. Diagnosing the source of contamination, and the vector or pathway through which contaminants travel is the key to a successful laboratory. Over the years, I have identified six distinct and separate vectors of contamination. If a contaminant arises in the laboratory, the cultivator should examine each vector category as being the possible cause of the problem. Through a process of elimination, the distressed cultivator can determine the vector through which the contaminants are spread. Once discovered, the vector can be closed, and the threat eliminated. If one vector is open, then a multitude of contaminants pass through it, often confounding the diagnoses of inexperienced cultivators.

The principal vectors of contamination are

1. The Cultivator
2. The Air
3. The Media
4. The Tools
5. The Inoculum
6. Mobile Contamination Units (MCUs)

The overriding coefficients affecting each vector are the number of contaminants and the exposure time. The more of each, the worse the infestation. This book does not go into detail as to the identity of the common contaminants. However, my previous book, The Mushroom Cultivator (1983), coauthored with Jeff Chilton, has extensive chapters on the identity of the molds, bacteria, and insects. The reader is encouraged to refer to that manual for the identification of contaminants. All contaminants are preventable by eliminating the six vectors of contamination. If you have difficulty determining the vector of contamination, or a solution to a problem, please refer to Chapter 25: Cultivation Problems and Their Solutions.

You, the Cultivator: The human body teems with populations of microorganisms. Diverse species of fungi (including yeast), bacteria, and viruses call your body home. When you are healthy, the populations of these microorganisms achieve an equilibrium. When you are ill, one or more of these groups proliferate out of control. Hence, unhealthy people should not be in a sterile laboratory, lest their disease organisms escape and proliferate to dangerous proportions.

Most frequently, contaminants are spread into the sterile laboratory via touch or breath. Also, the flaking of the skin is a direct cause. Many cultivators wear gloves to minimize the threat of skin-borne contaminants. I find laboratory gloves uncomfortable and prefer to wash my hands frequently, every 20 or 30 minutes with antibacterial soap. Additionally my hands are disinfected with 80% isopropyl alcohol immediately before inoculations, and every few minutes throughout the procedure.

The Air: Air can be described as a sea of microorganisms, hosting invisible contaminants, that directly contaminate sterilized media once exposed. Many particulates remain suspended. When a person walks into the laboratory, they not only bring in contaminants that will become airborne, but their movement disturbs the contaminant-laden floor, re-releasing contaminants into the lab’s atmosphere.

Several steps can prevent this vector of contamination. One rule of thumb is to always have at least three doors prior to entry into the sterile laboratory from the outside. Each room or chamber shall, by default, have fewer airborne particulates the nearer they are to the laboratory. Second, by positive-pressurizing the laboratory with an influx of air through micron filters, the airstream will naturally be directed against the entering personnel. (For the design of the air system for a laboratory, see Appendix 2.)

For those not installing micron filters, several alternative remedies can be employed. Unfortunately, none of these satisfactorily compare with the efficiency of micron filters. These “still-air” laboratories make use of aerosol sprays—either commercial disinfectants like Pine-Sol disinfectant or a dilute solution of isopropanol or bleach. The cultivator enters the work area and sprays a mist high up in the laboratory, walking backwards as they retreat. As the disinfecting mist descends, airborne particulates are trapped, carrying the contaminants to the floor. After a minute or two, the cultivator reenters the lab and begins his routine. (Note that you should not mix disinfectants—especially bleach and ammonia. Furthermore, this method can potentially damage your lungs or exposed mucous membranes. Appropriate precautions are strongly recommended.)

Without the exchange of fresh air, carbon dioxide levels will naturally rise from out-gassing by the mushroom mycelium. As carbon dioxide levels elevate, contaminants are triggered into growth. An additional problem with heavily packed spawn rooms is that with the rise of carbon dioxide, oxygen levels proportionately decrease, eventually asphyxiating the laboratory personnel. Unless the air is exchanged, the lab becomes stifling and contamination-prone. Since the only way to exchange air without introducing contaminants is by filtering, the combination of fans and micron filters is the only recourse.

Other cultivators use ultraviolet lights, which interfere with the DNA replication of all living organisms. UV lamps are effective when the contaminants are directly exposed. However, since shadowed areas are fully protected from UV exposure, contaminants in those regions remain unaffected. I disdain the use of UV in favor of the micron filter alternative. However, many others prefer their use. Note that the lab door should be electrically switched to the UV light so that the lamp turns off at entry. Obviously, exposure to UV light is threatening to human health, potentiating skin cancer and damage to the cornea of the eye.

Using an elastic film to seal the top and bottom of petri dishes. This eliminates the chance of airborne contamination entering during incubation.

Frequently, the vector of airborne contamination is easy to detect because of the way it forms on petri dishes. Airborne contaminants enter a petri dish either at the time the lid is opened (during pouring or inoculation) or during incubation. When the dish is opened, airborne contamination can spread evenly across the face of nutrient media. During incubation, contaminants creep in and form along the inside periphery of the petri dish. This latter occurrence is most common with laboratories with marginal cleanliness. A simple solution is to tape together the top and bottom of the petri dish directly after pouring and/or inoculation using elastic wax film. (Parafilm is one brand.) Plastic, stretchable kitchen wraps available in most grocery stores also can be used. These films prevent entry of contaminant spores that can occur from the fluctuation of barometric pressure due to natural changes in weather patterns.

One helpful practice in eliminating each vector of contamination at the source is to leave containers of media uninoculated. For instance, the cultivator should always leave some culture dishes uninoculated and unopened. These “blanks” as I like to call them, give the cultivator valuable information as to which vector of contamination is operating. At every step in the cultivation process, “blanks” should be used as controls.

The air in the growing rooms does not require the degree of filtration needed for the laboratory. For mushroom cultivators, cleaning the air by water misting is practical and effective. (Rain is nature’s best method of cleansing the air.) This cultivator’s regimen calls for the spraying down of each growing room twice a day. Starting from the ceiling and broadcasting a spray of water back and forth, the floor is eventually washed towards the center gutter. The room feels clean after each session. Each wash-down of a 1,000-square-foot growing room takes about 15 minutes. This regimen is a significant factor in maintaining the quality of the growing room environment.

The Media: Often the medium upon which a culture is grown becomes the source of contamination. Insufficient sterilization is usually the cause. Standard sterilization times for most liquid media is only 15 to 20 minutes at 15 psi or 250°F (121°C). However, this exposure time is far too brief for many of the endospore-forming bacteria prevalent in the additives currently employed by many cultivators. I recommend at least 40 minutes at 15 psi for malt extract or potato dextrose agars. If creating soil extracts, you must soak the soil for at least 24 hours, and then subject the extracted water to a minimum of 2 hours of sterilization. Indeed, soil extracts are resplendent with enormous numbers of contaminants. Because of the large initial populations, do not be surprised if some contaminants survive this prolonged sterilization period. Should they persist, then sterilizing the extracted water first, and then resterilizing it with standard malt sugar additives, is recommended. Clearly, sterilization efficiency is best achieved when the medium has a naturally low contamination content. (See “Preparing Nutrified Agar Media” in Chapter 12.)

Heat-sensitive sterilization indicator strips showing no sterilization, partial sterilization, and complete sterilization.

A good habit for all laboratory managers is to leave a few samples from each sterilization cycle uninoculated. Not inoculating a few petri dishes, grain jars, and sawdust/bran bags and observing them for a period of two weeks can provide valuable information about the vectors of contamination. These quality control tests can easily determine whether or not the medium is at fault or there has been a failure in the inoculation process. Under ideal conditions, the uninoculated units should remain contamination-free. If they contaminate within 48 to 72 hours, this is usually an indication that the media or containers were insufficiently sterilized. If the containers are not hermetically sealed, and contaminants occur near the end of three weeks, then the contamination is probably endemic to the laboratory, particularly where these units are being stored. Under ideal conditions, in a perfect universe, no contamination should occur no matter how long the uninoculated media is stored.

Many researchers have reported that sawdust needs only to be sterilized for 2 hours at 15 psi to achieve sterilization. (Royse et al. 1990; Stamets and Chilton, 1983.) However, this treatment schedule works for small batches. When you are loading an autoclave with hundreds of tightly packed bags of supplemented sawdust, sterilization for this short period will certainly lead to failure.

In the heat-treatment of bulk substrates, absolute sterilization is impractical. Here, sterilization is more conceptual than achievable. The best one can hope is that contaminants in the sawdust have been reduced to a level as to not be a problem, i.e., within the normal time frame needed for the mushroom mycelium to achieve thorough colonization. Again, the time period needed is approximately 2 weeks. Should colonization not be complete in two weeks, the development of contaminants elsewhere in the substrate is not unusual. Of course, by increasing the spawn rate, colonization is accelerated, and the window of opportunity favors the mushroom mycelium. The recommended sterilization times for supplemented sawdust are described in Chapter 17. Badham (1988) found that sterilization of supplemented sawdust under pressure for 4 hours at 19 psi was functionally similar (in terms of contamination reduction, growth rate, and yield of Shiitake) to high-temperature pasteurization at 190–194°F (88–90°C) for 14 hours at atmospheric pressure (1 psi). Remote sensing thermometers, placed at various depths, are used to determine temperature. When the coolest probe reads 190°F (88°C), steam is continuously supplied for a minimum of 12 hours, preferably 14 to 16 hours, depending on substrate mass.

Readers are forewarned not to jump to conclusions when comparing the heat-treatment sufficient for small batches and extrapolating this procedure to large batches. Since heat penetration varies with each substrate material’s density, and is co-dependent on the moisture content, the use of sterilization indicator strips is recommended to confirm that sterilization has actually occurred.

Yet another limiting factor is that media biochemically change, potentially generating toxins to mycelial growth. Should malt agar be cooked for 2 to 3 hours at 18 psi, the resulting medium changes into a clear amber liquid as sugars have been reduced. Under these conditions, cultivators say the medium has “caramelized” and generally discard the medium and make up a new batch. Contaminants won’t grow on this medium; nor does most mushroom mycelia. The cultivator is constantly faced with such dilemmas. What makes a good cultivator is one who seeks the compromises that lead most quickly to colonization and fruitbody production.

The Tools: In this category, all tools of the trade are included—from the scalpel to the pressure cooker to the media vessels. Insufficient sterilization of the tools can be a direct vector since contact with the media is immediate. Flame-sterilizing scalpels is the preferred method over topical disinfection with alcohol or bleach. However, the latter is used widely by the plant tissue culture industry with few problems.

If using a pressure cooker for sterilizing media and other tools, many forget that although the interior of the vessel has been sterilized, for all practical purposes, the outside of the vessel has not been. Contaminants can be easily picked up by the hands of the person handling the pressure cooker and redistributed to the immediate workstation—all the more reason one should disinfect before beginning transfers.

The Inoculum: The inoculum is the tissue that is being transferred, whether this tissue is a part of a living mushroom, mycelium from another petri dish, or spores. Bacteria and molds can infect the mushroom tissue and be carried with it every time a transfer is made. Isolation of the inoculum from the mushroom mycelium can be frustrating, for many of these contaminant organisms grow faster than the newly emerging mushroom mycelium. Cultivators must constantly “run” or transfer their mycelium away from these rapidly developing competitors. Several techniques can purify contaminated mycelium.

Mobile Contamination Units (MCUs): Mobile Contamination Units are organisms that carry and spread contaminants within the laboratory. These living macro-organisms act as vehicles spreading contaminants from one site to another. They are especially damaging to the laboratory environment, as they are difficult to isolate. Ants, flies, mites, and in this author’s case, small bipedal offspring (i.e., children) all qualify as potential MCUs. Typically, an MCU carries not one contaminant, but several.

Mites are the most difficult of these MCUs to control. Their minute size, their preference for fungi (both molds and mushroom mycelium) as food, and their penchant for travel, make them a spawn manager’s worst nightmare come true. Once mite contamination levels exceed 10%, the demise of the laboratory is only one generation away. The only solution, after the fact, is to totally shut down the laboratory. All cultures must be removed, including petri dishes, spawn jars, etc. The laboratory should then be thoroughly cleansed several times. I use a 10% household bleach solution. The floor, walls, and ceiling are washed. Two buckets of bleach solution are used—the first being the primary reservoir, the second for rinsing out the debris collected in the first wash-down. The lab is locked tight each day after wash-down. By thoroughly cleansing the lab three times in succession, you can eliminate or subdue the problem of mites to manageable levels. To prevent their recurrence, regenerate mycelia from carefully selected stock cultures.

Storing petri dish cultures on “sticky mats” prevents cross-contamination from mites.

I have discovered that “decontamination mats,” those labs use at door entrances to remove debris from footwear, are ideal for preventing cross-contamination from mites and similarly pernicious MCUs. Stacks of petri dishes are placed on newly exposed sticky mats on a laboratory shelf with several inches of space separating them. These zones of isolation, with culture dishes incubating upon a highly adhesive surface, make the migration of mites and other insects a most difficult endeavor. The upper sheet is removed every few weeks to expose a fresh, clean storage plane for new cultures.

All of these vectors are universally affected by one other variable: time of exposure. The longer the exposure of any of the aforementioned vectors of contamination, the more significant their impact. Good laboratory technicians are characterized not only by their speed and care, but also by their rhythm. Transfers are done in a systematically repetitive fashion. Controlling the time of exposure can have a drastic impact on the quality of laboratory technique.

Sterile tissue culture has revolutionized the biological sciences. For the first time in the history of human evolution, select organisms can be isolated from nature, propagated under sterile conditions in the laboratory, and released back into the environment. Since a competitor-free environment does not exist naturally on this planet¹, an artificial setting is created—the laboratory—in which select organisms can be grown in mass.

Louis Pasteur (1822–1895) pioneered sterile technique by recognizing that microorganisms are killed by heat, most effectively by steam or boiling water. Tissue culture of one organism—in absence of competitors—became possible for the first time. By the early 1900s growing organisms in pure culture became commonplace. Concurrently, several researchers discovered that mushroom mycelium could be grown under sterile conditions. However, the methods were not always successful. Without benefit of basic equipment, efforts were confounded by high levels of contamination and only after considerable effort was success seen. Nevertheless, methods slowly evolved through trial and error.

The monumental task of creating a sterile environment has been difficult, until recently. The invention of high-efficiency particulate air filters (called HEPA filters) has made sterile tissue culture practicable to all. In vitro (“within glass”) propagation of plants, animals, fungi, bacteria, and protozoa became commercially possible. Today, the HEPA (High Efficiency Particulate Air) filter is by far the best filtration system in use, advancing the field of tissue culture more so than any other invention.² When air is forcibly pressed through these filters, all contaminants down to .3 microns (µ) are eliminated with a 99.99% efficiency. This means only 1 of every 10,000 particulates exceeding .3 µ pass through. For all practical purposes, a sterile wind is generated downstream from the filter. The cultivator works within this airstream. This unique environment calls for unique techniques. A different set of rules now presides, the violation of which invites disaster.

Overview of techniques for growing mushrooms.

Sterile tissue culture technique fails if it solely relies on mechanical means. Sterile tissue culture technique is also a philosophy of behavior, ever-adjusting to ever-changing circumstances. Much like a martial artist, the cultivator develops keen senses, a prescience, to constantly evaluate threats to the integrity of the sterile laboratory. These enemies to sterile culture are largely invisible and are embodied within the term “contaminant.”

Diagrammatic representation of the effectiveness of filtration media. Dirty air is first filtered through a coarse prefilter (30% @ 10 µ), then an electrostatic filter (99% @ 1 µ), and finally through a High Efficiency Particulate Air (HEPA) filter (99.99% @ .3 µ). Only some free-flying endospores of bacteria and viruses pass through.

A contaminant is anything you don’t want to grow. Classically, Penicillium molds are contaminants to mushroom culture. However, if you are growing Shiitake mushrooms, and a nearby fruiting of Oyster mushrooms generates spores that come into the laboratory, then the Oyster spores would be considered the “contaminant.” So the definition of a contaminant is a functional one—it being any organism you don’t want to culture.

The laboratory environment is a sanctuary, a precious space, to be protected from the turmoils of the outside world. Maintaining the cleanliness of a laboratory is less work than having to deal with the aftermath wreaked by contamination. Hence, contaminants, as soon as they appear, should be immediately isolated and carefully removed so neighboring media and cultures are not likewise infected.

Overview of Techniques for Cultivating Mushrooms

The stages for cultivating mushrooms parallel the development of the mushroom life cycle. The mass of mycelium is exponentially expanded millions of times until mushrooms can be harvested. Depending upon the methodology, as few as two petri dishes of mushroom mycelium can result in 500,000–1,000,000 pounds of mushrooms in as short as 12 weeks! If any contaminants exist in the early stages of the spawn production process, they will likewise be expanded in enormous quantities. Hence, the utmost care must be taken, especially at the early stages of spawn production. Several tracks lead to successfully growing mushrooms. For indoor, high intensity cultivation, three basic steps are required for the cultivation of mushrooms on straw (or similar material) and for the cultivation of mushrooms on supplemented sawdust.

Within each step, several generations of transfers occur, resulting in a millionfold increase in mycelial mass. The sheer biological force of cellular activity boggles the mind. Scientists have estimated that this intense myceliation results in so many hyphal cells that more than a mile of mycelium impregnates every cubic inch. For me, the goal of the cultivator is to surf the mycelial wave as it crests. The mycelial momentum will carry the process forward so quickly that contaminants have little chance of catching up. This velocity of colonization nullifies any inherent imperfections at each step that would otherwise confound success.

Culturing Mycelium on Nutrified Agar Media: Mushroom mycelium is first grown on sterilized, nutrified agar media in petri dishes and/or in test tubes. Once pure and grown out, cultures are transferred using the standard cut-wedge technique. Each culture incubating in 100 × 15-mm petri dish can inoculate 10 quarts (liters) of grain spawn. (See this illustration.) If the mycelium is chopped in a high-speed stirrer and diluted, one petri dish culture can effectively inoculate 40–100 quarts (liters) of sterilized grain. These techniques are fully described in the ensuing pages.

Producing Grain Spawn: The cultures in the petri dishes can be expanded by inoculating sterilized grain housed in bottles, jars, or bags. Once grown out, each jar can inoculate 10 (range: 5 to 20) times its original mass for a total of three generations of expansions. Grain spawn can be used to inoculate pasteurized straw (or similar material) or sterilized sawdust. Grain spawn is inoculated into sawdust, straw, etc. at a rate between 3 and 15% (wet mass of spawn to dry mass of substrate).

Producing Sawdust Spawn: Sawdust spawn is inoculated with grain spawn. Sawdust spawn is best used to inoculate a “fruiting substrate,” typically logs or supplemented sawdust formulas. One 5-pound bag of sawdust spawn can effectively inoculate 5 to 20 times its mass, with a recommended rate of 10. Sawdust-to-sawdust transfers are common when growing Shiitake, Nameko, Oyster, Maitake, Reishi, or King Stropharia. Once grown out, each of these bags can generate 5 to 10 more sawdust spawn bags (S₁ to S₂). No more than two generations of expansion are recommended in the production of sawdust spawn. Spawn can be added to bulk substrates at rates, varying with the species and inclinations of the grower, equivalent to 5–20% (i.e., wet mass of spawn to dry mass of substrate).

Formulating the Fruiting Substrate: The fruiting substrate is the platform from which mushrooms arise. With many species, this is the final stage where mushrooms are produced for market. The formulas are specifically designed for mushroom production and are often nutrified with a variety of supplements. Some growers on bulk substrates expand the mycelium one more time, although I hesitate to recommend this course of action. Oyster cultivators in Europe commonly mix fully colonized, pasteurized straw into 10 times more pasteurized straw, thus attaining a tremendous amount of mycelial mileage. However, success occurs only if the utmost purity is maintained. Otherwise, the cultivator risks losing everything in the gamble for one more expansion.

Creating and expanding grain spawn. Sterilized grain is first inoculated from agar-grown cultures. Once grown out, each jar can inoculate 10 times more grain every two weeks.

This final substrate can be amended with a variety of materials to boost yields. With Shiitake, supplementation with rice bran (20%), rye flour (20%), soybean meal (5%), molasses (3–5%), or sugar (1% sucrose) significantly boosts yields by 20% or more. (For more information on the effects of sugar supplementation on Shiitake yields, see Royse et al. 1990.)

Preparing and pouring nutrified agar media into petri dishes.

Preparing Nutrified Agar Media

Many formulations have been developed for the cultivation of mushrooms on a semisolid agar medium. Agar is a seaweed-derived compound that gelatinizes water. Nutrients are added to the agar/water base that, after sterilization, promote healthy mushroom mycelium. The agar medium most commonly used with the greatest success is a fortified version of Malt Extract Agar (MEA). Other nutrified agar media that I recommend are Potato Dextrose Agar (PDA), Oatmeal Agar (OMA), and Dog Food Agar (DFA).

By supplementing these formulas with yeast and peptone, essential vitamins (such as thiamin) and amino acids (proteins) are provided. These supplements not only greatly stimulate the rate of growth, but the quality of the projected mycelial mat. Most agar media are simple and quick to prepare. What follows is some of my favorite nutrified agar recipes—of the 500 or more published.

Sterilize one of the following media for 45 minutes at 15 psi (= 1 kg/sq. cm.) in a pressure cooker.

(The above medium is abbreviated as MYA. With the peptone, which is not critical for most of the species described in this book, this medium is designated MYPA.)

(This medium is designated PDYA, or PDYPA if peptone is added. Note that only the broth from boiling the potatoes is used—the potatoes are discarded. The total volume of the media should equal 1 liter.)

(This rich medium is called OMYA. The oatmeal does not have to be filtered out although some prefer to do so.)

(This medium is called DFA.)

(This medium is known as CMYA and is widely used by mycological laboratories for storing cultures and is not as nutritious as the other above-described formulas.)

The pH of the above media formulations, after sterilizing, generally falls between 5.5 and 6.8. This medium can be further fortified with the addition of 3–5 grams of the end-substrate (in most cases hardwood sawdust) upon which mushrooms will be produced. If samples of soil or dung are desired, they first must be preboiled for at least 1 hour before adding to any of the above formulas. One potential advantage of the addition of these end-substrate components is a significant reduction in the “lag period.” The lag period is seen when mushroom mycelium encounters unfamiliar components. (Leatham and Griffin, 1984; Raaska, 1990). This simple step can greatly accelerate the mushroom life cycle, decreasing the duration of colonization prior to fruiting.

The dry components are mixed together, placed into a flask, to which 1 liter of water is added. This cultivator finds that well water, spring water, or mineral water works well. Chlorinated water is not recommended. Purchasing distilled water is unnecessary in my opinion. Once the media has been thoroughly mixed, the media flask is placed into a pressure cooker. The top of the media flask is either stopped with nonabsorbent cotton, wrapped in aluminum foil or, if equipped with a screw cap, the cap is loosely tightened. Steam sterilize for 45 minutes @ 15 psi (1 kg/cm²), equivalent to 250°F (120°C).

Pressure cookers or sterilizers that do not release pressure during the sterilization cycle are ideal. The old-fashioned pressure canners, those having weights sitting upon a steam valve, cause the media to boil as steam is vented. A huge mess ensues. The pressure cooker should ideally form a vacuum at cooldown. If, upon returning to atmospheric pressure, the cooker does not form a vacuum, the cultivator must place the pressure cooker in the clean room or open it in front of a laminar flow hood to prevent the introduction of contamination.

As the media cools within the pressure cooker, outside air is sucked in. If this air is ladened with contaminant spores, the media contaminates before the cultivator has handled the flask! One precaution is to saturate a paper towel with alcohol and drape it over the point where outside air is being drawn in. The cloth acts as a filter, lessening the chance of contaminants. Twenty minutes after the pressure has achieved atmospheric, most media vessels can be handled without a hot-glove. Prior to that time, media can be poured, but some form of protection is needed to prevent burns to the hands.

Agar coagulates water when added in excess of 10 grams per 1,000 milliliters H₂0. Only high-grade agar should be used. Various agars differ substantially in their ability to gelatinize water, their mineral and salt content, as well as their endemic populations of microorganisms, including bacteria. (Bacteria, if surviving, degelatinize the media.) Increasingly, pollution has affected the refinement of tissue-grade agar, causing the price to spiral. Agar substitutes such as Gelrite are widely used by the plant tissue culture industry. Although only a few grams are needed per liter, it does not result in a media firm enough for most mushroom cultivators. Mushroom cultivators desire a media with a semisolid, firm surface upon which the mycelium will grow. Plant tissue culturists seek a softer, gelatinous media so that plant starts will grow three-dimensionally, deep into media.

Sugars are essential for the healthy growth of mycelium. For media formulation, complex sources of sugars (carbohydrates and polysaccharides) are recommended. Cornsteep fermentative, cooked potatoes, wood, and barley malt extracts provide sugars and an assortment of basic minerals, vitamins, and salts helpful in the growth of the mushroom mycelium. From my experiences, simplified sugars, while they may support growth, are not recommended, as strains cannot be maintained for long without promoting mutation factors, senescence, and dieback. When the mycelium must work to extract sugars from the base medium, the overall vigor of the mycelial colony is enhanced. The reaction is not unlike that of a person exercising versus being lethargic. The effort increases vitality.

A variety of nitrogen- and carbohydrate-based supplements can be added to fortify the media. Strains grown repeatedly on mono-specific media for prolonged periods risk limiting the repertoire of digestive enzymes to just that specific media. In other words, a strain grown on one media adapts to it, and may lose its innate ability to digest larger, more complex and variable substrates. To prevent a strain from becoming media-specific, the following compounds are added to the MEA or PDA at various intervals, often in combinations:

Until some familiarity with media is established, the purchase of media from reputable companies is advised. Be forewarned, however, that the media designed for the growth of imperfect fungi (molds) available from large laboratory supply companies, favors the growth of many mold contaminants over that of mushroom mycelium. The media for most saprophytes should be adjusted to a pH of 5.5 to 6.5. Most, but not all, saprophytes (Thomas et al. 1998), acidify substrates, so near neutral, even basic substrates, become more acidic as the mushroom life cycle progresses.

Pouring Agar Media

One liter of malt extract agar medium will pour 20 to 40 (100 × 15-mm) petri dishes, depending upon the depth of the pour. Before you pour an agar medium, the tabletop is thoroughly wiped clean with an 80% concentration of isopropanol (isopropyl alcohol). Plastic petri dishes usually come presterilized and ready to use. Glass petri dishes should be first washed and sterilized in a petri dish holding rack simultaneous to the sterilization of the agar medium in an autoclavable flask. Prepouring media into glass dishes and then sterilizing is awkward. Media separation occurs, and any movement during the sterilization cycle (or while transferring the pressure cooker to the clean room) causes the liquefied media to spill out of the petri dishes. A huge mess results. However, this problem can be avoided if the pressure cooker cools overnight, for instance, and then is opened the next day. Be forewarned that if you choose this alternative, your pressure cooker must either form a vacuum, safely protecting the media before opening, or be placed into a HEPA filtered airstream to prevent contamination entry during cooldown.

With the micron filters mounted horizontally, and facing the cultivator, every movement is prioritized by degree of cleanliness. The cleanest articles remain upstream, the next cleanest downstream in second position, etc. The cultivator’s hands are usually furthest downwind from the media and cultures.

Pouring malt agar media into sterile petri dishes in front of laminar flow hood.

Starting a Mushroom Strain by Cloning

The surest method of starting a mushroom strain is by cloning. Cloning means that a piece of pure, living flesh is excised from the mushroom and placed into a sterilized, nutrient-enriched medium. If the transfer technique is successful, the cultivator succeeds in capturing a unique strain, one exhibiting the particular characteristics of the contributing mushroom. These features, and the expression thereof, is called the phenotype. By cloning, you capture the phenotype. Later, under the proper cultural conditions, and barring mutation, these same features are expressed in the subsequently grown mushrooms.

Several sites on the mushroom are best for taking clones. First, a young mushroom, preferably in “button” form, is a better candidate than an aged specimen. Young mushrooms are in a state of frenzied cell division. The clones from young mushrooms tend to be more vigorous. Older mushrooms can be cloned but have a higher contamination risk, and are slower to recover from the shock of transfer. Three locations resulting in a high number of successful clones are the area directly above the gills, the zone directly below the disk of the cap, and the interior tissue located at the base of the stem. The stem base, being in direct contact with the ground, is often the entry point through which fly larvae tunnel, carrying with them other microorganisms. I prefer the genetically rich area directly giving rise to the gills and their associated spore-producing cells, the fertile basidia.

Glove boxes are considered “old tech.” To retrofit a glove box into a laminar flow hood, simply cut out the back panel, replace with a similarly sized HEPA filter, and build a 6-inch-deep plenum behind the filter. A squirrel-cage blower is mounted on top, forcing air into the plenum. Air is forced through the filter. Downstream from the filter, a sterile wind flows in which inoculations can be conducted.

The procedure for cloning a mushroom is quite simple. Choose the best specimen possible, and cut away any attached debris. Using a damp paper towel, wipe the mushroom clean. Lay the specimen on a new sheet of paper towel. Flame-sterilize a sharp scalpel until it is red hot. Cool the scalpel tip by touching the nutrient agar medium in a petri dish. This petri dish will be the same dish into which you transfer the mushroom tissue. Carefully tear the mushroom apart from the base, up the stem, and through the cap. With one-half of this split mushroom, cut a small section (“square”) of flesh about the size of a kernel of grain. Quickly transfer the excised tissue to the nutrient-filled petri dish, and submerge the tissue into the same location where the scalpel tip had been cooled. When you insert the tissue part way into the agar medium, in contrast to resting it on the surface, the mushroom tissue has maximum contact with the life-stimulating media. Each time a clone is taken, the scalpel is re-sterilized, cooled, and then the tissue is transferred into a separate petri dish following the aforementioned steps.

One carefully keeps the hot scalpel tip and the freshly poured media plates upstream of the mushroom being cloned or the mycelium being transferred. Next downstream are the cultivator’s hands. No matter how many times one has disinfected his or her hands, one should presume they are replete with contaminants. (To test this, wash your hands, disinfect your fingertips with alcohol and fingerprint newly poured media plates. In most cases, the plates will contaminate with a plethora of microorganisms.)

Some use a “cooling dish” into which the hot scalpel tip is inserted before touching the living flesh of a mushroom. Repeatedly cooling the scalpel tip into the same medium-filled petri dish before each inoculation is not recommended. A mistake with any inoculation could cause contamination to be retransmitted with each transfer. If, for instance, a part of the mushroom were being invaded by Mycogone, a mushroom-eating fungus, one bad transfer would jeopardize all the subsequent inoculations. Only one cooling dish should be used for each transfer; the same dish that receives the cloned tissue. In this fashion, at least one potential cross-contamination vector is eliminated.

When cloning a mushroom for the first time, I recommend a minimum of ten repetitions. If the mushroom specimen is exceedingly rare, cloning into several dozen dishes is recommended. As the specimen dries out, viable clones become increasingly less likely. With the window of opportunity for cloning being so narrow, the cultivator should clone mushrooms within hours of harvesting. If the mushrooms must be stored, then the specimen should refrigerated at 35–40°F (1–5°C). After 3 to 4 days from harvest, finding viable and clean tissue for cloning is difficult.

Ideal sites for cloning a mushroom: directly above the gills or at the base of the stem. Young, firm mushrooms are best candidates for cloning.

A few days to 2 weeks after cloning the mushroom, the tissue fragment springs to life, becoming fuzzy in appearance. Contaminants usually become visible at this stage. As a rule, the cultivator always transfers viable mycelium away from contamination, not the other way around. The essential concept here, is that the cultivator “runs” with the mycelium, subculturing away from contamination as many times as is necessary until a pure culture is established.

Each transfer from an older petri dish culture to a newer petri dish moves upstream. The scalpel is brought into contact with heat. The tip is cooled into the dish destined to receive the mycelium. The lid of this dish is lifted, the scalpel is cooled, and then the lid is replaced. Next, the lid of the dish hosting the mature mycelium is opened. The mycelium is cut. The wedge is transferred to the newly poured media plate. With the lid replaced, the culture is labeled and moved aside. The process is repeated until a number of plates are inoculated.

As each lid is lifted, care is taken not to extend the fingers beyond the lip of each top. The overhanging of fingers results in flaking off contaminants into the petri dish. Furthermore, the lids are lifted with their undersides catching the sterile airstream. If the lids must be laid down, they are positioned undersides up, upstream of the operations area, so that contaminants are not picked up off the table. Always presume the air coming off the face of the micron filter is cleaner than the work surface in front of it.

Culture transfers that are fast, evenly repeated, and in quick succession usually are the most successful. The simplest acts dramatically impact sterile technique. Merely breathing over exposed petri dishes significantly affects contamination levels. Singing, for instance, is associated with a high rate of bacterial contamination. One bewildered professor discovered that her soliloquies in the laboratory—she sang as the radio blared—were a direct cause of high contamination rates. An alert student discovered her digression from sterile technique upon passing the door to her lab. This illustrates that the cultivator’s unconscious activities profoundly influence the outcome of tissue culture transfers. Every action in the laboratory has significance.

Cloning Wild Specimens vs. Cultivated Mushrooms

Many people ask, “What is wrong with just cloning a nice-looking specimen from each crop of cultivated mushrooms to get a new strain?” Although morphological traits can be partially selected for, senescence factors are soon encountered with each subsequent clone, a condition known as replicate fading. Generating cultures in this fashion is a fast track to genetic demise, quickly leading to loss of vigor and yield. By not returning to stock cultures, to young cell lines, one goes further downstream one linear chain of cells. Mushrooms, like every sexually reproducing organism on this planet, can generate a limited number of cell divisions before vitality falters. Sectoring, slow growth, anemic mushroom formation, malformation, or no mushroom formations at all, are all classic symptoms of senescence. Although senescence is a frequently encountered phenomenon with cultivators, the mechanism is poorly understood. (See Kuck et al. 1985.)

In the competitive field of mycology, strains are all-important. With the afore-stated precautions and our present-day technologies, strains can be preserved for decades, probably centuries, all-the-while kept within a few thousand cell divisions from the original culture. Since we still live in an era of relatively rich fungal diversity, the time is now to preserve as many cell lines from the wild as possible. As biodiversity declines, the gene pool contracts. I strongly believe that the future health of the planet may well depend upon the strains we preserve this century.

Paul Stamets’s 12-foot-long laminar flow bench designed for commercial cultivation. Simple, but effective.

How to Collect Spores

A culture arising from cloning is fundamentally different from a culture originating from spores. When spores are germinated, many different strains are created, some incompatible with one another. A cultivator will not know what features will be expressed until each and every strain is grown out to the final stage, that of mushroom production. This form of genetic roulette results in some very unusual strains, some more desirable than others.

A laminar flow bench suitable for home or small-scale commercial cultivation.

Mushroom spores are collected by taking a spore print. Spore prints are made by simply severing the cap from the stem, and placing the cap, gills down, upon a piece of typing paper, or glass. Covering the mushroom cap with a bowl or plate lessens evaporation and disturbance from air currents. Within 24 hours, often only 12, millions of spores fall in a beautiful pattern according to the radiating symmetry of the gills. A single mushroom can produce from 100,000 to 100,000,000 spores!

I prefer to collect spores on plates of glass, approximately 6 by 8 inches. The glass is washed with soapy water, wiped dry, and then cleaned with rubbing alcohol (isopropanol). The two pieces of glass are then joined together with a length of duct tape, to create, in effect a binding. The mushrooms are then laid on the cleaned, open surface for spore collection. After 12 to 24 hours, the contributing mushroom is removed, dried, and stored for later reference purposes. The remaining edges of the glass are then taped. The result is a glass-enclosed “Spore Booklet,” which can be stored at room temperature for years. Spores are easily removed from the smooth glass surface for future use. And, spores can be easily observed without increasing the likelihood of contamination.

Spores have several advantages. Once a spore print has been obtained, it can be sealed and stored, even sent through the mail, with little ill effect. For the traveler, spore prints are an easy way to send back potential new strains to the home laboratory. Spores offer the most diverse source of genetic characteristics, far more than the phenotypic clone. If you want the greatest number of strains, collect the spores. If you want to capture the characteristics of the mushroom you have found, then clone the mushroom by cutting out a piece of living tissue.

Germinating Spores

To germinate spores, an inoculation loop, a sterilized needle, or scalpel is brought into contact with the spore print. (I prefer an inoculation loop.) I recommend flame-sterilizing an inoculation loop until red hot and immediately cooling it in a petri dish filled with a sterilized nutrient medium. The tip immediately sizzles as it cools. The tip can now touch the spore print without harm, picking up hundreds of spores in the process. By touching the tip to the medium-filled petri dish first, not only is it cooled, but also the tip becomes covered with a moist, adhesive layer of media to which spores easily attach. The tip can now be streaked in a “S” pattern across the surface of another media dish.

Taking spore prints on typing paper.

With heavy spore prints, the “S” streaking technique may not sufficiently disperse the spores. In this case, the scalpel or inoculation loop should be immersed into a sterile vial holding 10 cc (ml) of water. After shaking thoroughly, one drop (or ≈ ¹/₃₀th of 1 cc.) is placed onto the surface of the nutrient medium in each petri dish. Each dish should be tilted back and forth so that the spore-enriched droplet streaks across the surface, leaving a trail of dispersed spores. In either case, spores will be spread apart from one another, so that individual germination can occur.

Five to fifteen days later, spores can be seen germinating according to the streaking pattern. Colonies of germinating spores are subcultured into more petri dishes. After the mycelium has grown away from the subculture site, a small fragment of pure mycelium is again subcultured into more petri dishes. If these cultures do not sector, then backups are made for storage and future use. This last transfer usually results in individual dikaryotic strains that are labeled. Each labeled strain is then tested for productivity. Mini-culture experiments must be conducted prior to commercial-level production.

The spore print can be folded and rubbed together so that spores drop onto nutrient agar media. This method is not the best as concentrated populations of spores are grouped together.

An inoculation loop is sterilized, in this case with a BactiCinerator, and then cooled into the “receiving” dish. The spores are picked up by touching the inoculation loop to the spore print. The spore-laden inoculation loop is streaked across the surface of the sterilized, nutrient-filled medium in a “S” pattern.

When a concentrated mass of spores is germinated, the likelihood of bacteria and weed fungi infesting the site is greatly increased. Bacteria replicate faster than mushroom spores can germinate. As a result, the germinating spores become infected. Mycelium arising from such germination is frequently associated with a high contamination rate, unfortunately, often not experienced until the mycelium is transferred to grain media. However, if the spore prints are made correctly, contamination is usually not a problem.

Once inoculated, the petri dish cultures should be taped with an elastic film (such as Parafilm), which protects the incubating mycelium from intrusive airborne contaminants. (See example.)

Spores germinate according to the streaking pattern. A small portion is excised and transferred to a new, nutrient-agar-filled petri dish.

Purifying a Culture

Many cultures originating from spores or tissue are associated with other microorganisms. Several techniques are at one’s disposal for cleaning up a culture. Depending upon the type, and level of contamination, different responses are appropriate.

One way of cleaning a bacterially infested culture is by sandwiching it between two layers of media containing an antibiotic such as gentamycin sulfate. The hyphae, the cells composing the mycelium, are arranged as long filaments. These filamentous cells push through the media while the bacteria are left behind. The mycelium arising on the top layer of media will carry a greatly reduced population of bacteria, if any at all. Should the culture not be purified the first time using this procedure, a second treatment is recommended, again subculturing from the newly emerged mycelium. Repeated attempts increase the chances of success.

Scanning electron micrograph of spores germinating.

Scanning electron micrograph of spores infected with bacteria.

If the culture is mixed with other molds, then the pH of the media can be adjusted to favor the mushroom mycelium. Generally speaking, many of the contaminant fungi are strong acidophiles whereas Oyster mushrooms grow well in environments near a neutral pH. If these mold fungi sporulate adjacent to the mycelia of mushrooms, isolation becomes difficult.² Remember, the advantage that molds have over mushroom mycelia is that their life cycles spin far faster, and thousands of mold spores are generated in only a few days. Once molds produce spores, any disturbance—including exposure to the clean air coming from the laminar flow hood—creates satellite colonies.

One rule is to immediately subculture all points of visible growth away from one another as soon as they become visible. This method disperses the colonies, good and bad, so they can be dealt with individually. Repeated subculturing and dispersal usually result in success. If not, then other alternative methods can be implemented.

Mycelia of all fungi grow at different rates and are acclimated to degrading different base materials. One method I have devised for separating mushroom mycelium from mold mycelium is by racing the mycelia through organic barriers. Glass tubes can be filled with finely chopped, moistened straw, wood sawdust, rolled cardboard, and even crushed corncobs (without kernels) and sterilized. The contaminated culture is introduced to one end of the tube. The polyculture of contaminants of mushroom mycelium races through the tube, and with luck, the mushroom mycelium is favorably selected, reaching the opposite end first. At this point, the cultivator simply transfers a sample of emerging mycelium from the end of the tube to newly poured media plates. The cultures are then labeled, sealed, and observed for future verification. This technique relies on the fact that the mycelia of fungi grow at different rates through biodegradable materials. The semiselectivity of the culture/host substrate controls the success of this method.

Cultivators develop their own strategies for strain purification. Having to isolate a culture from a background of many contaminants is inherently difficult. Far easier is it to implement the necessary precautions when initially making a culture so that running away from contamination is unnecessary.

Every sexually reproducing organism on this planet is limited in the number of its cell replications. Without further recombination of genes, cell lines decline in vigor and eventually die. The same is true with mushrooms. When one considers the exponential expansion of mycelial mass, from two microscopic spores into tons of mycelium in a matter of weeks, mushroom mycelium cell division potential far exceeds that of most organisms. Nevertheless, strains die and, unless precautions have been taken, the cultures may never be retrieved.

Once a mushroom strain is taken into culture, whether from spores or tissue, the resultant strains can be preserved for decades under normal refrigeration, perhaps centuries under liquid nitrogen. In the field of mycology, cultures are typically stored in test tubes. Test tubes are filled with media, sterilized, and laid at a 15- to 20-degree angle on a table to cool. (Refer to Chapter 12 for making sterilized media. I often double the formula so that the test tubes will gel sufficiently.) These are called test tube slants. Once inoculated, these are known as culture slants.

Culture slants are like “backups” in the computer industry. Since every mushroom strain is certain to die out, one is forced to return to the stock library for genetically younger copies. Good mushroom strains are hard to come by, compared to the number of poor performers isolated from nature. Hence, the Culture Library, aka the Strain Bank, is at the pivotal center of any mushroom cultivation enterprise.

Stock cultures, in quadruplicate, sealed in a plastic bag, stored in a cedar box, and refrigerated for years at 35°F (1–2°C) until needed.

Examples of cultures originating from stock culture libraries from sources in United States, Canada, Thailand, and China. Most culture libraries do not send cultures in duplicate nor indicate how far the cultures have grown since inception.

Preserving the Culture Library

One culture in a standard 100 × 15-mm petri dish can inoculate 50 to 100 test tube slants measuring 100 × 20 mm After incubation for 1 to 4 weeks, or until a luxurious mycelium has been established, the test tube cultures are placed into cold storage. I seal the gap between the screw cap and the glass tube with a commercially available elastic, wax-like film. (Those test tube slants not sealed with this film are prone to contaminate with molds after several months of cold storage.) Culture banks in Asia commonly preserve cultures in straight test tubes whose ends are stuffed with a hydrophobic cotton or gauze. The gauze is sometimes covered with plastic film and secured tightly with a rubber band. Other libraries offer cultures in test tubes fitted with a press-on plastic lid especially designed for gas exchange. The need for gas exchange is minimal—provided the culture’s growth is slowed down by timely placement into cold storage. Culture slants stored at room temperature have a maximum life of 6 to 12 months, whereas cultures kept under refrigeration survive for 5 years or more. Multiple backups of each strain are strongly recommended as there is a natural attrition over time.

I prefer to seal test-tube slants in plastic Ziploc bags. Three to four bags, each containing four slants, are then stored in at least two locations remote from the main laboratory. This additional safety precaution prevents events like fires, electrical failure, misguided law enforcement officials, or other natural disasters from destroying your most valuable asset—the Culture Library.

Household refrigerators, especially modern ones, suffice. Those refrigerators having the greatest mass, with thermostatic controls limiting variation in temperature, are best for culture storage. With temperature variation, condensation occurs within the culture tubes, spreading a contaminant, should it be present, throughout the culture. Therefore, limiting temperature fluctuation to 2–3°F (1°C) is crucial for long-term culture preservation. Furthermore, when mushroom cultures freeze and thaw repeatedly, they die.

If one has ten or more replicates, stock cultures of a single strain can be safely stored for 5 years by this method. As a precaution, however, one or two representative culture slants should be retrieved every year, brought to room temperature for 48 hours, and subcultured to newly filled media dishes. Once revived, and determined to be free of contamination, the mycelium can once again be subcultured back into test tube slants, and returned to refrigeration. This circular path of culture rotation ascertains viability and prolongs storage with a minimum number of cell divisions. I cannot overemphasize the importance of maintaining cell lines closest to their genetic origins.

Cryogenic storage—the preservation of cultures by storage under liquid nitrogen—is the best way to preserve a strain. Liquid nitrogen storage vessels commonly are held at −302°F (−150°C). Test tube slants filled with a specially designed cryoprotectant medium help the mycelium survive the shock of sudden temperature change. (Such cryoprotectants involve the use of a 10% glycerol and dextrose medium.) Wang and Jong (1990) discovered that a slow, controlled cooling rate of −1°C per minute resulted in a higher survival rate than sudden immersion into liquid nitrogen. This slow reduction in temperature allowed the mycelium to discharge water extracellularly, thus protecting the cells from the severe damage ice crystals pose. Further, they found that strains were better preserved on grain media than on agar media. However, for those with limited liquid nitrogen storage space and large numbers of strains, preservation of grain media is not as practical as preserving strains in ampules or test tubes of liquid cryoprotectant media.

Of all the mushrooms discussed in this book, only strains of the Paddy Straw Mushroom, Volvariella volvacea, should not be chilled. V. volvacea demonstrates poor recovery from cold storage—both from simple refrigeration at 34°F (2°C) or immersion into liquid nitrogen at −300°F (−150°C). When the mycelium of this tropical mushroom is exposed to temperatures below 45°F (7.2°C), drastic dieback occurs. Strains of this mushroom should be stored at no less than 45−50°F (7−10°C) and tested frequently for viability. When cultures are to be preserved for prolonged periods at room temperature, many mycologists cover the mycelium with liquid paraffin. (For more information, consult Jinxia and Chang, 1992.)

When you are retrieving cultures from prolonged storage, the appearance of the cultures can immediately indicate potential viability or clear inviability. If the mycelium is not aerial, but is flat, with a highly reflective sheen over its surface, then the culture has likely died. If the culture caps have not been sealed, contaminants, usually green molds, are often visible, giving the mycelium a speckled appearance. These cultures make re-isolation most difficult. Generally speaking, success is most often seen with cultures having aerial, cottony mycelium. Ultimately, however, cultivators cannot determine viability of stored cultures until they are subcultured into new media and incubated for 1 to 3 weeks.

The Stamets “P” Value System

The Stamets “P” value system is simply an arithmetic scale I have devised for measuring the expansion of mycelium through successive inoculations from one 100 × 15-mm petri dish to the next. The number of cell divisions across a petri dish fall within a range of cell wall lengths. Of the septate strains of fungi, some have cells as short as 20 µ while others have cells 200 µ and longer. The Stamets “P” Value (SPV) benefits cultivators by indicating how close to the origin their culture is at any point in time by simply recording the number of petri dishes the mycelium has grown through. When a culture has been isolated from contaminants, usually in one or two transfers, the first pure culture is designated as P¹. When the mycelium has filled that dish, the next dish to receive the mycelium is called P². Each culture is labeled with the date, species, collection number, strain code, “P” Value, and medium (if necessary). Thus, a typical example from one of my culture dishes reads:

Agaricus blazei

P⁵

2/12

An Agaricus blazei, Himematsutake, culture is labeled to indicate genus, species, “P” Value, and date.

The date 2/12 refers to the time the medium was inoculated. Spawn created from such young cultures, in contrast to one grown out 100 times as far, produces more mushrooms. The “P” value system is essentially a metric ruler for measuring relative numbers of cell divisions from the culture’s birth. (Note that a square centimeter of mycelium is generally transferred from one culture dish to the next.) I have strains in my possession, from which I regularly regenerate cultures, that are 10 years old, and kept at a P² or P³. Having ten to twenty backup culture slants greatly helps in this pursuit.

For purposes of commercial production, I try to maintain cell lines within P¹⁰, that is, within ten successive transfers to medium-filled petri dishes. Many strains of Morels, Shiitake, and King Stropharia express mutations when transferred on media for more than ten petri dishes. Morels seem particularly susceptible to degeneration. Morchella angusticeps loses its ability to form micro-sclerotia in as few as six or seven plate transfers from the original tissue culture.

The slowing of mycelium may also be partly due to media specificity, i.e., the agar formula selectively influences the type of mycelial growth. To ameliorate degenerative effects, the addition of extracted end-substrates (sawdust, straw, etc.) favors the normal development of mycelium. The introduction of the end-substrate acquaints the mushroom mycelium with its destined fruiting habitat, challenging the mycelium and selectively activating its enzymatic systems. This familiarity with the end-substrate greatly improves performance later on. Parent cells retain a “genetic memory” passed downstream through the mycelial networks. Mycelia grown in this fashion are far better prepared than mycelia not exposed to such cultural conditions. Not only is the speed of colonization accelerated, but also the time to fruiting is shortened. Only 1–3 grams of substrate is recommended per liter of nutrient medium. Substrate additives high in endospores (such as most soils) should be treated by first boiling the sample in an aqueous concoction for at least an hour. After boiling, sugar, agar, and other supplements can be added. The media is then sterilized using standard procedures described in Chapter 12.

By observing the cultures daily, you’ll see the changeover of characteristics that defines the health of the mycelial mat. What this book strives to show is the mycelium of each species and its transformations on the path to fruiting. Variations from the norm should alert the cultivator that the strain is in an active state of mutation. Rarely do mutations in the mycelium result in a stronger strain. Paying attention to the structure of the leading edge of the actively growing mycelium often gives the cultivator clues to the health of the culture. Rapidly diverging finger-like growth patterns are usually a positive reflection of vitality, and as a rule, their loss is foreboding of a sickening strain.

Classic forms of mushroom mycelia.

Iconic Types of Mushroom Mycelium

Each mushroom species produces a recognizable type of mycelium whose variations fall within a range of expressions. Within a species, multitudes of strains can differ dramatically in their appearance. In culture, mushroom strains reveal much about the portion of the mushroom life cycle that is invisible to the mere forager for wild mushrooms. This range of characteristics—changes in form and color, rate of growth, fragrance, even volunteer fruitings of mushrooms in miniature—reveals a wealth of information to the cultivator, defining the strain’s “personality.”

Form: Mycelia can be categorized into several different, classic forms. For ease of explanation, these forms are delineated on the basis of their macroscopic appearance on the two-dimensional plane of a nutrient-filled petri dish. As the mycelium undergoes changes in its appearance over time, this progression of transformations tells the cultivator much about what is normal and what is abnormal. The standard media I use is Malt Yeast Agar (MYA) fortified with peptone (MYPA).

Linear: Linear mycelium is arranged as diverging, longitudinal strands. Typically, the mycelium emanates from the center of the petri dish as a homogeneously forming mat. Shiitake (Lentinula edodes) and initially Oyster (Pleurotus ostreatus) mycelia fall in this category. Morels produce a rapidly growing, finely linear mycelium, which thickens in time. In fact, Morel mycelium is so fine that during the first few days of growth, the mycelium is nearly invisible, detected only by tilting the petri dish back and forth so that the fine strands can be seen on the reflective sheen of the agar medium’s surface.

Rhizomorphic mycelium diverging from cottony mycelium soon after spore germination.

Classic rhizomorphic mycelium.

Rhizomorphic: Often similar to linear mycelium, rhizomorphic mycelium is often called “ropey.” In fact, rhizomorphic mycelium is composed of braided, twisted strands of mycelium, often of varying diameters. Rhizomorphic mycelium supports primordia and is encouraged by selecting these sites for further transfer. The disappearance of rhizomorphs is an indication of loss of vigor. Lion’s Mane (Hericium erinaceus), the King Stropharia (Stropharia rugosoannulata), Button mushrooms (Agaricus brunnescens, Agaricus bitorquis), Himematsutake (Agaricus blazei), Magic Mushrooms (Psilocybe cubensis and Psilocybe cyanescens), and Clustered Woodlovers (Hypholoma capnoides and H. sublateritium) are examples of mushrooms producing classically rhizomorphic mycelia. Some types of rhizomorphic mycelia take on a reflective quality, resembling the surface of silk.

Pseudo-rhizomorphic and cottony mycelia.

Cottony: This type of mycelium is common with strains of Oyster mushrooms (Pleurotus species), Shaggy Manes (Coprinus comatus), and Hen-of-the-Woods (Grifola frondosa). Looking like tufts of cotton, the mycelium is nearly as aerial in its growth as it is longitudinal. Cottony mycelium is commonly called “tomentose” by mycologists. When rhizomorphic mycelium degenerates with age, tomentose formations typically take over.

Zonate mycelium.

Zonate: Cottony mycelium often shows concentric circles of dense and light growth, or zones. Zonate mycelium is often characteristic of natural changes in the age of the mycelium. The newest mycelium, on the periphery of the culture, is usually light in color. The more aged mycelium, towards the center of the culture, becomes strongly pigmented. Zonations can also be a function of the natural circadian cycles, and even when cultures are incubated in laboratories, and even though temperatures are kept constant and away from the influence of sunlight. Growth occurs in spurts, creating rings of alternating density. This feature is commonly seen in species of Ganoderma, Hypholoma, and Hypsizygus.

Matted or appressed: This type of mycelium is typical of Reishi (Ganoderma lucidum) after 2 weeks of growth on 2% malt extract agar media. So dense is this mycelial type, that a factory-sharpened surgical blade can’t cut through it. The mycelium tears off in ragged sheaths as the scalpel blade is dragged across the surface of the agar medium. Many species develop matted mycelia over time, especially the wood rotters. Cultures that mysteriously die often have mycelium that appears matted but whose surface is flat and highly reflective.

Powdered: This form of mycelium is best exemplified by Laetiporus sulphureus (Polyporus sulphureus), aka Chicken-of-the-Woods. The mycelium breaks apart with the least disturbance. In front of a laminar flow bench, the sterile wind can cause chains of mycelium (hyphae) to be airborne. Free-flying hyphae can cause considerable cross-contamination problems within the laboratory.

Hyphal aggregates of the Fairy Ring Mushroom (Marasmius oreades) and Shiitake (Lentinus edodes).

Unique Formations: Upon the surface of the mycelial mat, unique formations occur that can be distinguished from the background mycelium. They are various in forms. One common form is hyphal aggregates, cottony ball-like or shelf-like structures. I view hyphal aggregates as favorable formations when selecting out rapidly fruiting strains of Shiitake. Hyphal aggregates often evolve into primordia, the youngest visible stages of mushroom formation. Marasmius oreades, the Fairy Ring Mushroom, produces shelf-like forms that define the character of its mycelium. Stropharia rugosoannulata, the King Stropharia, has uniquely flattened, plate-like zones of dense and light growth, upon which hyphal aggregates often form. Morels and many other mushrooms produce dense, spherical formations called sclerotia. (See examples.) Sclerotia can be brightly colored and abundant, as is typical of many strains of Morchella angusticeps, or dark colored and sparse like those of Polyporus umbellatus.

The mycelia of some mushrooms generate asexual structures called coremia (broom-like bundles of spores), which resemble many of the black mold contaminants. Some of these peculiar formations typify Pleurotus cystidiosus, Pleurotus abalonus, and Pleurotus smithii. I know of one Ph.D. mycologist, not knowing that some Oyster mushrooms go through an asexual stage, promptly discarded the cultures I gave her because they were “contaminated.”

Mushroom strains, once characterized by rhizomorphic mycelia, often degenerate after repetitive subculturing. Usually the decline in vigor follows this pattern: A healthy strain is first rhizomorphic in appearance, and then after months of transfers the culture sectors, forming diverging “fans” of linear, cottony, and appressed mycelium. Often an unstable strain develops mycelium with aerial tufts of cotton-like growth. The mycelium at the center of the petri dish, giving birth to these fans of disparate growth, is genetically unstable, and being in an active state of decline, sends forth mutation-ridden chains of cells. Often, the ability to give rise to volunteer primordia on nutrified agar media, once characteristic of a strain, declines or disappears entirely. Speed of growth decelerates. If not entirely dying out, the strain is reduced to an anemic state of slow growth, eventually incapable of fruiting. Prone to disease attack, especially by parasitic bacteria, the mushroom strain usually dies.

This unique mushroom forms concentric rings of sclerotia in culture. These rings form every few days and when separated from the mother mycelium can give rise directly to mushrooms.

Color: Most mushroom species produce mycelia that undergo mesmerizing transformations in pigmentation as they age, from the youngest stages of growth to the oldest. One must learn the natural progression of coloration for each species’ mycelium. Since the cultivator is ever watchful for the occurrence of certain colors that can forebode contamination, knowing these changes is critical. Universally, the color green is bad in mushroom culture, usually indicating the presence of molds belonging to Penicillium, Aspergillus, or Trichoderma.

White: The color shared by the largest population of saprophytic mushrooms is white. Oyster (Pleurotus spp.), Shiitake (Lentinula edodes), Hen-of-the-Woods (Grifola frondosa), the King Stropharia (Stropharia rugosoannulata), and most Magic Mushrooms (Psilocybes) all have whitish-colored mycelium. Some imperfect fungi, like Monilia, however, also produce a whitish mycelium. (See The Mushroom Cultivator, Stamets and Chilton, 1983.)

Yellow/Orange/Pink: Nameko (Pholiota nameko) produces a white mycelial mat that soon yellows. Oyster mushrooms, particularly Pleurotus ostreatus, exude a yellowish to orangish metabolite over time. These metabolites are sometimes seen as droplets on the surface of the mycelium or as excessive liquid collecting at the bottom of the spawn containers. Strains of Reishi, Ganoderma lucidum, vary considerably in their appearances, most often projecting a white mycelium that, as it matures, becomes yellow as the agar medium is colonized. A pink Oyster mushroom, Pleurotus djamor, and Lion’s Mane, Hericium erinaceus, both have mycelium that is initially white, and as the cultures age, develop strong pinkish tones. Chicken-of-the-Woods (Polyporus or Laetiporus sulphureus) has an overall orangish mycelium. Kuritake (Hypholoma sublateritium) has mycelium that is white at first, and in age can become dingy yellow-brown.

Brown: Some mushroom species, especially Shiitake, undergo changes in coloration as they age. Normally, Shiitake becomes brown over time. It would be abnormal for Shiitake mycelium not to brown in age or when damaged. Similarly, the Poplar Mushroom (Agrocybe aegerita) produces an initially white mycelium that browns with maturity. Morel mycelium is typically brown after a week of growth.

Miniature mushroom (Gymnopilus luteofolius) forming on malt agar media. Note proportion of mushroom relative to mycelial mat.

Blue: Lepista nuda, the Wood Blewit, produces a blue, cottony mycelium. Many species not yet cultivated are likely to produce blue mycelia. Although the number of species generating blue mycelium is few, most of the psilocybian mushrooms are characterized by mycelium that bruises bluish when damaged. Beyond these examples, blue tones are highly unusual and warrant examination through a microscope to ascertain the absence of competitor organisms, particularly the blue-green Penicillium molds. Although unusual, I have seen cultures of an Oyster mushroom, P. ostreatus var. columbinus, and a luminescent mushroom, Mycena chlorophos, that produce whitish mycelium streaked with bluish tones.

Black: Few mushrooms produce black mycelium. Some Morel strains cause the malt extract medium to blacken, especially when the petri dish culture is viewed from underneath. The parasitic Honey mushroom, Armillaria mellea, forms uniquely black rhizomorphs. A pan-tropical Oyster mushroom, called Pleurotus cystidiosus, and its close relatives P. abalonus and P. smithii, have white mycelia that become speckled with black droplets.

A strain of the Abalone Oyster Mushroom, Pleurotus cystidiosus. This mushroom species is dimorphic—having an alternative life cycle path. The black droplets are resplendent with spores and are not contaminants.

Multicolored: Mycelia can be zonate, with multicolored tones in concentric circles around the zone of transfer. The concentric circles of growth are usually diurnal, reflecting rates of growth dictated by the passage of day to night. All of the species described in the past five categories undergo unique color changes. This sequence of color transformation defines the unique “personality” of each strain. I have yet to see a mycelium of greater beauty than that of the extraordinary Psilocybe mexicana, the sacramental Teonanacatl of Mexico. Its mycelium is initially white, then yellow, golden, brown, and sometimes streaked through with bluish tones. (See Color Plate 2, opposite 176 in The Mushroom Cultivator by Stamets and Chilton, 1983.)

Mushroom primordia on malt agar media. Upper left: Ganoderma lucidum, Reishi. Upper right: Agrocybe aegerita, the Black Poplar Mushroom. Lower left: Pleurotus djamor, the Pink Oyster Complex. Lower right: Hericium erinaceus, the Lion’s Mane mushroom.

Fragrance: The sensation most difficult to describe and yet so indispensable to the experienced spawn producer is that of fragrance. The mycelium of each species out-gasses volatile wastes as it decomposes a substrate, whether that substrate is nutrified agar media, grain, straw, sawdust, or compost. The complexity of these odors can be differentiated by the human olfactory senses. In fact, each species can be known by a fragrance signature. As the mass of mycelium is increased, odors become more pronounced. Although odor is generally not detectable at the petri dish culture stage, it is distinctly noticed when a red-hot scalpel blade touches living mycelium. The sudden burst of burned mycelium emits a fragrance specific to each species. More useful to cultivators is the fragrance signature emanating from grain spawn. Odors can constantly be used to check spawn quality and even species identification.

On rye grain, Oyster mycelium emits a sweet, pleasant, and slightly anise odor. Shiitake mycelium has an odor reminiscent of fresh, crushed Shiitake mushrooms. Chicken-of-the-Woods (Laetiporus or Polyporus sulphureus) is most unusual in its fragrance signature: Grain spawn has the distinct scent of butterscotch combined with a hint of maple syrup! King Stropharia (Stropharia rugosoannulata) has a musty, phenolic smell on grain but a rich, appealing woodsy odor on sawdust. Maitake (Grifola frondosa) mycelium on grain reminds me of day-old, cold corn tortillas! Worst of all is Enokitake—it smells like week-old dirty socks. Mycologists have long been amazed by the fact that certain mushrooms produce odors that humans can recognize elsewhere in our life experiences. Some mushrooms smell like radishes, some like apricots, maple syrup, and even bubble gum! Is there any significance to these odors? Or is it just a fluke of nature?

The Event of Volunteer Primordia on Nutrified Agar Media

The voluntary and spontaneous formation of miniature mushrooms in a petri dish is a delightful experience for all cultivators. In this chapter, attention and insights are given for many species. By no means is this knowledge static. Every cultivator contributes to the body of knowledge each time a mushroom is cultured.

The cultivator plays an active role in developing strains by physically selecting those that look “good.” Integral to the success of the mushroom life cycle is the mycelial path leading to primordia formation. To this end, the mushroom and the cultivator share common interests. The occurrence of primordia not only is a welcome affirmation of the strain’s identity but is also indicative of its readiness to fruit. Hence, I tend to favor strains that voluntarily form primordia.

Two approaches lead to primordia formation from cultured mycelium. The first is to devise a standard media, a background against which all strains and species can be compared. After performance standards are ascertained, the second approach is to alter the media, specifically improving and designing its composition for the species selected. As a group, those strains needing bacteria to fruit do not form primordia on sterile media.

Several mushroom species have mycelial networks that, when they are disturbed at primordia formation, result in a quantum leap in the vigor of growth and in the number of subsequently forming primordia. With most strains, however, the damaged primordia revert back to vegetative growth. The following list of species are those that produce volunteer primordia on 2% enriched malt extract agar, supplemented with .2% yeast and .005% gentamicin sulfate.¹ The formation of primordia on this media is often strain specific. The following species are known by this author to benefit from the timely disturbance of primordia on the nutrified agar medium. Those that do benefit from disturbance are excellent candidates for liquid-inoculation techniques.

When a mushroom is brought into culture from the wild, little can be known about its performance until trials are conducted. Each mushroom strain is unique. Most saprophytic fungi, especially primary saprophytes, are easy to isolate from nature. Whether or not they can be grown under “artificial” conditions, however, remains to be seen. Only after the cultivator has worked with a strain, through all the stages of the culturing process, does a recognizable pattern of characteristics evolve. Even within the same species, mushroom strains vary to surprising degrees.

A cultivator develops an intimate, co-dependent relationship with every mushroom strain. The features listed below represent a mosaic of characteristics, helping a cultivator define the unique nature of any culture. By observing a culture’s daily transformations, a complex field of features emerges, expressing the idiosyncrasies of each strain. Since tons of mushrooms are generated from a few petri dish cultures in a matter of weeks, these and other factors play essential roles in the success of each production run.

Once familiar with a particular culture, the cultivator is alerted to variations from the norm indicating possible genetic decline or mutation. When differences in expression occur, not attributable to environmental factors such as habitat (substrate) or air quality, the cultivator should become alarmed. One of the first features in the telltale decline of a strain is “mushroom aborts.” Aborting mushrooms represent failures in the mushroom colony, as a singular organism, to sustain total yield of all of its members to full maturity. The next, classic symptom to be witnessed with a failing strain is the decline in the population of primordia. Fewer and fewer primordia appear. Those that do form are often dwarfs with deformed caps. These are just some of the features to be wary of should your strain not perform to proven standards.

A good strain is easy to keep, and difficult to impossible to regain once it senesces. Do not underestimate the importance of stock cultures. And do not underestimate the mutability of a mushroom strain once it has been developed. I use the following checklist of 28 features for evaluating and developing a mushroom strain. Most of these features can be observed with the naked eye.

28 Features for Evaluating and Selecting a Mushroom Strain

The mushroom strain, its unique personality—mannerisms, sensitivities, yield expressions—is the foundation of any mushroom farm. When a strain goes bad, production precipitously declines typically followed by a proliferation of disease organisms. Therefore, cultivators must continuously scrutinize new strains to find candidates worthy of production. Once a strain has been developed, multiple backups are made in the form of test tube slants. Test tube slants ensure long-term storage for future use. The cold storage of test tube slants limits the rate of cell divisions, protecting the strain from mutation and senescence factors.

Although this list is not all-inclusive, and can be expanded upon by any knowledgeable cultivator, it reveals much about the goals cultivators ultimately seek in bringing a strain into culture. However, the following list arises from a uniquely human, self-serving perspective: creating food and medicines for human consumption. If selecting a strain for bioremediation, or for some ecological function, this list would be considerably altered.

Recovery: The time for a mushroom strain to recover from the concussion of inoculation. This is often referred to as “leap off.” Oyster and Morel strains are renowned for their quick “leap off” after transfer, evident in as short as 24 hours. Some strains of mushrooms show poor recovery. These strains are difficult to grow commercially unless they are re-invigorated—through strain development and/or media improvement.

Grain spawn 3 days and 8 days after inoculation. Visible recovery of spawn 2 days after inoculation is considered good; 1 day is considered excellent.

Rate of growth: Strains differ substantially in their rate of growth at all stages of the mushroom growing process. Once the mycelium recovers from the concussion of inoculation, the pace of cell divisions quickens. Actively growing mycelium achieves a mycelial momentum, which if properly managed, can greatly shorten the colonization phase, and ultimately the production cycle. (See chart at end of chapter.)

The fastest of the species described in this book has to be the Morels. Their mycelia typically cover a standard 100 × 15-mm petri dish in 3 to 5 days at 75°F (24°C). Oyster strains, under the same conditions, typically take 5 to 10 days depending on the size of the transfer and other factors. All other conditions being the same (i.e., rate of inoculation, substrate, incubation environment), strains taking more than 3 weeks to colonize nutrified agar media, grain, or bulk substrates are susceptible to contamination. With many strains, such as Oyster and Shiitake, a sufficient body of knowledge and experience has accumulated to allow valid comparisons. With strains relatively new to mushroom science, benchmarks must first be established.

Quality of the mycelial mat: Under ideal conditions, the mycelial mat expands and thickens with numerous hyphal branches. The same mycelium under less than perfect conditions casts a mycelial mat finer and less dense. Its “hold” on the substrate is loose. In this case, the substrate, although fully colonized, falls apart with ease. In contrast, mycelium properly matched with its substrate forms a mat tenacious in character. The substrate and the mycelium unify, requiring considerable strength to rip the two apart. This is especially true of colonies of Oyster, King Stropharia, and Psilocybe mushrooms.

Healthy mushroom mycelium running through cardboard.

Some species of mushrooms, by nature, form weak mycelial mats. This is especially true of the initially fine mycelium of Morels. Pholiota nameko, the slimy Nameko mushroom, generates a mycelium considerably less tenacious than Lentinula edodes, the Shiitake mushroom, on the same substrate and at the same rate of inoculation. Once a cultivator recognizes each species’ capacity for forming a mycelial network, recognizing what is a “strong” or “weak” mycelium soon becomes obvious.

Adaptability to single component, formulated, and complex substrates: Some strains are well known for their adaptability to a variety of substrates. Oyster and King Stropharia are good examples. Oyster mushrooms, native to woodlands, can be grown on cereal straws, corn stalks, sugarcane bagasse, coffee leaves, and paper (including a multitude of paper by-products). These species’ ability to utilize such a spectrum of materials and produce mushrooms is nothing short of amazing. Although most strains can grow vegetatively on a wide assortment of substrates, many are narrowly specific in their substrate requirements for mushroom production.

Speed of colonization to fruiting: Here, strains can fall into two subcategories. One group produces mushrooms directly after colonization. This group includes the Oyster mushrooms (Pleurotus pulmonarius, some warm-weather P. ostreatus strains), Lion’s Manes (Hericium erinaceus), and the Paddy Straw (Volvariella volvacea) mushrooms. Others, like the Woodlovers (Hypholoma capnoides and H. sublateritium) require a sustained resting period after colonization, sometimes taking up to several weeks or months before the onset of fruiting.

Microflora dependability/sensitivity: Some gourmet and medicinal mushroom species require a living community of microorganisms. The absence of critical microflora prevents the mycelium from producing a fruitbody. Hence, these species will not produce on sterilized substrates unless microflora are introduced. The King Stropharia (Stropharia rugosoannulata), Zhu Ling (Polyporus umbellatus), and the Button mushroom (Agaricus brunnescens) are three examples. Typically these species benefit from the application of a microbially enriched soil or “casing” layer.

The Blewit, Lepista nuda, has been suggested by other authors as being a species dependent upon soil microbes. However, I have successfully cultivated this mushroom on sterilized sawdust apart from any contact with soil microorganisms. The Blewit may fall into an intermediate category whose members may not be absolutely dependent on microflora for mushroom production, but are quick to fruit when paired with them.

Phototropic response of Psilocybe cubensis to light.

Photosensitivity: The sensitivity of mushrooms to light is surprising to most who have heard that mushrooms like to grow in the dark. In fact, most of the gourmet and medicinal mushrooms require and favorably react to light. The development of mushrooms is affected by light in two ways. Initially, primordia form when exposed to light. Even though thousands of primordia can form in response to brief light exposure, these primordia will not develop into normal-looking mushrooms unless light is sustained. Without secondary exposure to light post primordia formation, Oyster mushrooms, in particular, malform. Their stems elongate, and the caps remain undeveloped. This response is similar to that seen in high CO₂ environments. In both cases, long stems are produced. This response makes sense if one considers that mushrooms must be elevated above the CO₂ rich environment within a substrate for the caps and subsequently forming spores to be released. Oyster, Shiitake, and Reishi all demonstrate strong photosensitivity.

Requirement for cold shock: The classic initiation strategy for most mushrooms calls for drastically dropping the temperature for several days. With many temperate mushroom strains, the core temperature of the substrate must be dropped below 60–65°F (15–18°C) before mushroom primordia will set. Once primordia is formed, temperatures can be elevated to the 70–80°F (21–27°C) range. This requirement is particularly critical for strains that have evolved in temperate climates, where distinct seasonal changes from summer to fall precede the wild mushroom season. Because of their cold shock requirement, growing these strains during the summer months or, for instance, in Southern California would not be advisable. Strains isolated from subtropical or tropical climates generally do not require a cold shock. As a rule, warm-weather strains grow more quickly, fruiting in one-half the time than do their cold-weather cousins. Experienced cultivators wisely cycle strains through their facility to best match the prevailing seasons, thus minimizing the expense of heating and cooling.

Requirement for high temperature: Many warm-weather strains will not produce at cooler temperatures. Unless air temperature is elevated above the minimum threshold for triggering fruiting, the mycelium remains in stasis, what cultivators term “overgrowth” or “overvegetation.” Volvariella volvacea, the Paddy Straw mushroom, will not produce below 75°F (24°C) and in fact, most strains of this species die if temperatures drop below 45°F (7.2°C). Pleurotus pulmonarius, a rapidly growing Oyster species, thrives between 75 and 85°F (24–30°C) and is not prevented from fruiting until temperatures drop below 45°F (7.2°C). With most temperature-tolerant strains, higher temperatures cause the mushrooms to develop more quickly. Another example is Pleurotus citrinopileatus, the Golden Oyster, which fruits when temperatures exceed 65°F (18°C).

Number and distribution of primordial sites: For every cultivator, the time before and during primordia formation is one of high anxiety, expectation, and hope. The changeover from vegetative colonization to this earliest period of mushroom formation is perhaps the most critical period in the mushroom life cycle. With proper environmental stimulation, the cultivator aids the mushroom organism in its attempt to generate abundant numbers of primordia. Aside from the influences of the environment and the host substrate, a strain’s ability to produce primordia is a genetically determined trait. Ideally, a good strain is one that produces a population of numerous, evenly distributed primordia within a short time frame.

Phototropic response of Ganoderma lucidum to light.

Site-specific response to low carbon dioxide levels: As the mycelium digests a substrate, massive amounts of carbon dioxide are produced, stimulating mycelial growth but preventing mushroom formation. The pronounced reaction of mycelium to generate primordia in response to lowering carbon dioxide gives the cultivator a powerful tool in scheduling fruitings. Strains vary in their degree of sensitivity to fluctuations in carbon dioxide. Mushroom cultivators who grow Oyster mushrooms in plastic columns or bags desire strains that produce primordia exactly where holes have been punched. The holes in the plastic become the ports for the exodus of carbon dioxide. At these sites, the mycelium senses the availability of oxygen, and forms primordia. This response is very much analogous to the mushroom mycelium coming to the surface of soil or wood, away from the rich CO₂ environment from within, to the oxygenated atmosphere of the outdoors, where a mushroom can safely propel spores into the wind currents for dispersal to distant ecological niches. With strains supersensitive to carbon dioxide levels, the cultivator can take advantage of this site-specific response for controlled cropping, greatly facilitating the harvest.

Number of primordia forming versus those maturing to an edible size: Some strains form abundant primordia; others seem impotent. Those that do produce numerous primordia can be further evaluated by the percentage of those forming compared to those developing to a harvestable stage. Ideally, 90% of the primordia mature. Poor strains can be described as those that produce primordial populations where 50% or more fail to grow to maturity under ideal conditions. Aborted primordia become sites of contamination by molds, bacteria, and even flies.

Number of viable primordia surviving for second and third flushes: Some strains of Oyster and Button mushrooms, especially cold-weather varieties, form the majority of primordia during the first initiation strategy. Many primordia lay dormant, yet viable, for weeks, before development. After the first flush of mushrooms mature and is harvested, the resting primordia develop for the second and subsequent flushes.

Duration between first, second, and third flushes: An important feature of any mushroom strain is the time between “breaks” or flushes. The shorter the period, the better. Strains characterized by long periods of dormancy between breaks are more susceptible to exploitation by insects and molds. By the third flush a cultivator should have harvested 90% of the potential crop. The sooner these crops can be harvested, the sooner the growing room can be rotated into another crop cycle. The rapid cycling of younger batches poses less risk of contamination.

Spore load factors: Over the years, the white Button mushroom, Agaricus brunnescens, has been genetically selected for small gills, thick flesh, and a short stem. In doing so, a fat mushroom with a thick veil covering short gills emerged, a form that greatly extended shelf life. As a general rule, once spores have been released in mass, the mushroom soon decomposes. Hence, strains that are not heavy spore producers at the time of harvest are attractive to cultivators. Additionally, the massive release of spores, particularly by Oyster mushrooms, is an environmental hazard to workers within the growing rooms and is taxing on equipment. I have seen, on numerous occasions, the spores from Oyster mushrooms actually clog and stop fans running at several hundred rpms, ruining their motors.

Another mushroom notorious for its spore load is Reishi, Ganoderma lucidum. Within the growing rooms, a rust-colored spore cloud forms, causing similar, although less severe, allergic reactions seen to those with Oyster mushrooms. Rather than emitting spores for just a few days, as with most fleshy mushrooms, the woody Ganoderma generates spores for weeks as it slowly develops.

Appearance (form, size, and color of the harvestable mushrooms): Every cultivator has a responsibility to present a quality product to the marketplace. Since gourmet mushrooms are relatively new, national standards have yet to be set in the United States for distinguishing grades. As gourmet mushrooms become more common, the public is becoming increasingly more discriminating.

What a cultivator may lose in yield from picking young mushrooms is offset by many benefits. Young mushrooms are more flavorful, tighter fleshed, often more colorful, and able to ship and store longer than older ones. Crop rotation, with much less associated spore load, is likewise accelerated through the harvest of adolescent forms. Diseases are less likely and consistency of production is better assured.

One general feature is common to all mushrooms in determining the best stage for picking: the cap margin. Cap margins reveal much about future growth. At the youngest stages, the cap margin is incurved, soon becoming decurved, and eventually flattening at maturity. The ideal stage for harvest is midway between incurved and decurved. During this period, spore release is well below peak production. Since both the incurving cap and the partial veil (if present) protect the gills, adolescent mushrooms are not nearly as vulnerable to damage. Himematsutake, Agaricus blazei, is an excellent example—the “drumstick” form is the prime stage for havesting. (See example.) For more information, please consult Chapter 23.

Duration from storage to spoilage—preservation: An important aspect of evaluating any strain is its ability to store well. Spoilage is accelerated by bacteria, which thrive under high moisture and stagnant air conditions. A delicate balance must be struck between temperature, air movement, and moisture to best prolong storage of mushrooms.

Some species and strains are more resistant to spoilage than others. Shiitake mushrooms store and ship far better, on the average, than Oyster mushrooms. Some Oyster mushrooms, especially the slow-forming cold-weather strains, survive under cold storage longer than the warm-weather varieties. In either case, should spores be released, and germinate, bacterial infection quickly sets in.

Abatement of growth subsequent to harvest: Yet another feature determining preservation is whether or not the mushrooms stop growing after picking. Many mushrooms continue to enlarge, flatten out, and produce spores long after they have been harvested. This is especially distressing for a cultivator picking a perfect-looking, young specimen one day only to find it transformed into a mature adult the next. This continued growth often places growers and distant distributors into opposing viewpoints concerning the quality of the product. A strain of Pleurotus pulmonarius, especially the widely cultivated “Pleurotus sajor-caju” is one such example. I like to describe this strain of Oyster mushrooms as being “biologically out of control.”

I photographed this unsavory package directly after purchasing it from a major grocery store chain. Mushrooms in this condition, if eaten, cause extreme gastrointestinal discord. This is the “sajor-caju” variety of Pleurotus pulmonarius, also known as the Phoenix Oyster mushroom, and has been a favorite of large-scale producers. Subsequent to harvest, hundreds of primordia soon form on the decomposing mushrooms.

Necrosis factors and the protection of dead tissue from competitors: After a mushroom has been picked, tissue remnants become sites for attack by predator insects and parasitic molds. Some species, Shiitake, for instance, have a woodier stem than cap. When Shiitake is harvested by cutting at the base of the stem, the stem butt, still attached to the wood substrate, browns and hardens. As the stem butt dies, a protective skin forms. This ability to form a tough outer coat of cells protects not only the leftover stem remnant from infestation, but also prevents deep penetration by predators. Since most Pleurotus ostreatus strains are not graced with this defense, extreme caution must be observed during harvest so no dead tissue remains. The “sajor-caju” variety of Pleurotus pulmonarius is surprising in its ability to reabsorb dead tissue, even forming new mushrooms on the dead body remnants of previously harvested mushrooms.

Genetic stability/instability: Since all strains eventually senesce, genetic stability is of paramount concern to every cultivator. Signs of a strain dying are its inability to colonize a substrate, produce primordia, or develop healthy mushrooms. Typical warning signs are a delay in fruiting schedules and an increasing susceptibility to disease. These symptoms are a few of many that suggest strain senescence.

Flavor: Strains of the same species differ substantially in flavor. The cultivator needs to determine each strain’s flavor/texture and be sensitive to customer feedback. Americans favor mildly flavored mushrooms whereas the Japanese are accustomed to more strongly tasting varieties. Pleurotus citrinopileatus, the Golden Oyster mushroom, is extremely astringent until thoroughly cooked, a good example that flavor is affected by the length of cooking. Generally speaking, younger mushrooms are better flavored than older ones. The King Stropharia, Stropharia rugosoannulata, is a good example, being exquisitely edible when young, but quickly losing flavor with maturity. Shiitake, Lentinula edodes, has many flavor dimensions. If the cap surface was dry before picking, or cracked as in the so-called “Donko” forms, a richer flavor is imparted during cooking. Although the cracking of the cap skin is environmentally induced, the cultivator can select strains whose cap cuticle easily breaks in response to fluctuating humidity.

Texture: The stage at harvest, the duration and temperature of cooking, and the condiments with which mushrooms are cooked all markedly affect textural qualities. Judging the best combination of texture and flavor is a highly subjective experience, often influenced by cultural traditions. Most connoisseurs prefer mushrooms that are slightly crispy and chewy but not tough. Steamed mushrooms are usually limp and soft and easily break apart, especially if they have been sliced before cooking. By tearing the mushrooms into pieces, rather than cutting, firmness is preserved. These attributes play an important role in the sensual experience of the mycophagist.

Aroma: Few experiences arouse as much interest in eating gourmet mushrooms as their aroma. When Shiitake and Shimeji are stir-fried, the rich aroma causes the olfactory senses to dance, setting the stage for the taste buds. Once paired with the experience of eating, the aroma signature of each species is a call to arms (or “forks”) for mycophagists everywhere. My family begins cooking mushrooms first when preparing dinner. The aroma undergoes complex transformations as water is lost and the cells are tenderized. (Please refer to the recipes in Chapter 24.)

Sensitivity to essential elements—minerals and metals: Gray Leatham (1989) was one of the first researchers to note that nanograms of tin and nickel were critical to successful fruitbody formation in Shiitake. Without these minute amounts of tin and nickel, Shiitake mycelium is incapable of fruiting. Manganese also seems to play a determinate role in the mushroom life cycle. Many other minerals and metals are probably essential to the success of the mushroom life cycle. Since these compounds are abundant in nature, cultivators need not be concerned about their addition to wood-based substrates. Only in the designing of “artificial” wood-free media does the cultivator run the risk of creating an environment lacking in these essential compounds.

Ability to surpass competitors: An essential measure of a strain’s performance is its ability to resist competitor fungi, bacteria, and insects. Strains can be directly measured by their ability to overwhelm competitor molds, especially Trichoderma, the forest green mold growing on most woods. On thoroughly sterilized substrates, a mushroom strain may run quickly and without hesitation. Once a competitor is encountered, however, strains vary substantially in their defensive/offensive abilities. Oyster mushrooms (Pleurotus ostreatus), for instance, are now recognized for nematode-trapping abilities. I have even witnessed Sciarid flies, attracted to aromatic Oyster mycelium, alighting too long, and becoming stuck to the aerial mycelium. The degree by which flies are attracted to a particular Oyster mushroom strain can be considered a genetically determined trait—a feature most cultivators would like to suppress.

Nutritional composition: Mushrooms are a rich source for amino acids (proteins), minerals, and vitamins. The percentages of these compounds can vary between strains. Substrate components contain precursors that can be digested and transformed into tissue to varying degrees by different strains. This may explain why there is such a variation in the protein analysis of, for instance, Oyster mushrooms. The analyses are probably correct. The strains vary in their conversion efficiencies of base substrate components into mushroom flesh.

Production of primary and secondary metabolites: A strain’s ability to compete may be directly related to the production of primary and secondary metabolites. All fungi produce extracellular enzymes that break down food sources. Myriad numbers of metabolic by-products are also generated. These extracellular compounds are released through the cell walls of the mycelium, enabling the digestion of potential food sources. Enzymes, such as ligninase that breaks down the structural component in wood, are extremely effective in reducing complex carbon chains, including carbohydrates and hydrocarbons.

Secondary metabolites usually occur well after colonization. A good example is the yellow fluid, the exudate, frequently seen collecting at the bottom of aged spawn containers. Pleurotus spp., Stropharia rugosoannulata, and Ganoderma lucidum are abundant producers of secondary metabolites. Complex acids and ethylene-related products are examples of such secondary metabolites. These metabolites forestall competition from other fungi and bacteria.

Production of medicinal compounds: Bound within the cell walls of mushrooms are chains of heavy-molecular-weight sugars, polysaccharides. These sugars compose the structural framework of the cell. Many mushroom polysaccharides are new to science and are named for the genus in which they have been first found, such as lentinan (from Shiitake, Lentinula edodes), flammulin or “FVP” (from Enokitake, Flammulina velutipes), grifolin or grifolan (from Maitake, Grifola frondosa), etc. Research in Asia shows that these cell wall components enhance the human immune system. Cellular polysaccharides are more concentrated, obviously, in the compact form of the mushroom than in the loose network of the mycelium. In traditional Chinese pharmacopeia, the sexually producing organ—in this case, the mushroom—has long been viewed as a more potent source for medicine than its infertile representations.

Cell components other than polysaccharides have been proposed to have medicinal effects. Strain selection could just as well focus on their molecular yields. Precursors in the substrate may play determinant roles in the selective production of these components when matched with various strains.

Optimization of Expansion of Mushroom Mycelium

Each strain is unique in its potential for growth. Here, the expansion of mycelial mass peaks on Day 25, with more than 9,000 billion (9 trillion) colonies per gram. Soon thereafter cell viability precipitously declines as substrate nutrition becomes increasingly limited. This trend is a classic biological model that is repeated throughout nature. The goal of the cultivator is to move the mycelium at its peak rate of growth into new media.

Making grain spawn is the next step in the exponential expansion of mycelial mass. The intent and purpose of grain spawn is to boost the mycelium to a state of vigor where it can be launched into bulk substrates. The grain is not only a vehicle for evenly distributing the mycelium, but also a nutritional supplement. Whole grain is used because each kernel becomes a mycelial capsule, a platform from which mycelia can leap into the surrounding expanse. Smaller kernels of grain provide more points of inoculation per pound of spawn. Many large spawn producers prefer millet, a small kernel grain, because it stores well and end-users like its convenience. Most small-scale, gourmet mushroom growers utilize organically grown rye or wheat grain. Virtually all the cereal grains (including maize) can be used for spawn production. Every spawn maker favors the grain that, from experience, has produced the most satisfactory results.

The preferred rate of inoculation depends upon many factors, not the least of which is cost. If a cultivator buys spawn from a commercial laboratory, the recommended rate is often between 3 and 7% of substrate mass. What this means is that for every 1,000 pounds of substrate (dry weight), 30–70 pounds of spawn (wet weight) is suggested. Since grain spawn is usually around 50% absolute moisture, this rate of inoculation would be equivalent to 1.5–3.0% of dry spawn/dry substrate.

Cultivators who generate their own spawn frequently use a 10–20% rate of moist spawn/dry substrate, or by this example 100–200 pounds of fresh spawn per 1,000 pounds of substrate. This increased rate of spawning accelerates colonization, narrows the window of opportunity for competitor invasion, and significantly boosts yields. Clearly those making their own spawn have an advantage over those buying spawn from afar. One major drawback of high spawning rates is increased thermogenesis, the heating up of the substrate as the mycelium consumes it. Anticipating and controlling thermogenesis is essential for success, and can be used to great advantage. This subject will be explored in detail later on.

Single kernel of rye grain encapsulated with a sheath of mycelium.

Of the many cereal grains used for creating spawn, rye grain is the most popular. Wheat, milo, sorghum, corn, and millet are also utilized. There are two approaches for preparing grain spawn. The first is to submerge grain in a cauldron of boiling water. After an hour of boiling (or steeping), the saturated grain is drained of water (discarded) and scooped into waiting spawn containers. Fitted with a lid having a ⅜- to ½-inch hole and lined with a microporous filter disk, the grain-filled jar is sterilized in a pressure cooker. This method is widely used and recommended by many spawn producers because even moisture absorption and consistency are assured.

The progressive colonization of sterilized grain by mushroom mycelium.

The second method calls for first placing dry grain into glass spawn jars, adding the recommended amount of water, preferably hot, and allowing the jars to sit overnight. The jars are capped with lids, complete with a ⅜- to ½-inch hole and fitted underneath with a microporous filter disk. By allowing the grain to soak for 12 to 24 hours, the heat-resistant endospores of bacteria germinate and become sensitive to heat sterilization. Before use, the filter disks should be soaked in a weak (5%) bleach solution to dislodge and disinfect any embedded contaminants. The next day, the jars are reshaken by striking them against a rubber tire, or similar surface, to mix together the more moist and drier grain kernels. Once shaken, they are promptly placed into the sterilizer. The advantage of this method is that it is a one-step procedure. A case can be made that starches and other nutrients are preserved with this method since the water is not discarded. Proponents of the first method argue that not only is their starting material cleaner, but this second technique causes the grains to have an uneven moisture content. The reader must decide which is most suitable. Neither method, in my opinion, merits endorsement over the other.

With excess water, grain kernels explode, exposing the nutrients within, and making them more susceptible to contamination. Exploded grain kernels also cause clumping and become sites of depressed gas exchange, environments wherein bacteria proliferate. The shape of the intact grain kernel, with its protective outer surface, selectively favors the filamentous mushroom mycelium and produces spawn that separates readily upon shaking.

Both of the above-described preparation techniques have their strong and weak points.

Suitable Containers for Incubating Grain Spawn

One method for preparing grain spawn is to simply pour dry grain into glass jars, then add water, allow to sit overnight, and then sterilize. Advantages are a one-step process, less fuel consumption, and less handling. One disadvantage is uneven water absorption.

Formulas for Creating Grain Spawn

Moisture content plays a critical role in the successful colonization by mushroom mycelium of sterilized grain. If the grain is too dry, growth is retarded, with the mycelium forming fine threads and growing slowly. Should too much water be added to the grain, the grain clumps, and dense, slow growth occurs. Higher moisture contents also encourage bacterial blooms. Without proper moisture content, spawn production is hampered, even though all other techniques may be perfect.

The optimum moisture for grain spawn falls within 38–55% moisture, with an ideal around 50%. To determine the moisture content of grain from any supplier, before formulating, weigh 100 grams of the grain, dry out the grain, and reweigh the remaining mass. (This can easily be determined by drying out the moistened grain in an oven for 300°F (150°C) for 8 hours.) The difference in weight is the water lost, or the percentage moisture. Now water is added to achieve a targeted moisture content. Once cooked, a sample of grain is taken and oven dried. To check the proposed formula, just take the mass of the lost water divided by the total mass of dried grain and the lost water. This will give you a moisture percentage. Remember that moisture percentage is the mass of water divided by total mass, lost water included. This is not a ratio of water to dry mass, but a percentage of water over total mass. (This is a common mistake among certain schools of Shiitake growers and wood lot managers.) Once a targeted moisture content is achieved, spawn growers rely on volumetric scoops customized to the new formula.

Since grain comes to the consumer with an inherent moisture content of 8–15%, less water is added than might be expected to achieve the right moisture content for spawn production. Each cultivator may want to adjust the following proportions of water to grain to best fit his or her needs. Keep in mind that 1 liter (1,000 ml) of water weighs 1 kilogram (1000 g). A quart is almost a liter and for the purposes of the mushroom cultivator can be used interchangeably. (The amount of grain within each vessel is specified in the following formulas. A variation of only 5–7% between the two volumes is not statistically significant.) Gypsum is added to help keep the kernels separated after sterilization and to provide calcium and sulfur, basic elements promoting mushroom metabolism. (See Stoller, 1962; Leatham and Stahlman, 1989.)

Spawn incubating in ½-gallon (2-liter), 1-gallon (4-liter), and 2.5-gallon (10-liter) containers. Note filter media that prevent contamination but allow respiration.

A delicate balance between the mass of grain and added water must be preserved to promote the highest quality spawn. As the spawn container is increased in its volume, slightly less water is added proportionately. Whereas the percentage of moisture content can be nearly 60% in a small spawn jar, a large container will have a moisture content of only 38%. Anaerobic environments are encouraged with larger masses of grain, a phenomenon that necessitates a drier medium and extended exposure to pressurized steam. Cultivators should adjust these baseline formulas to best meet their specific circumstances. Jars and bags must be fitted with microporous filters for adequate gas exchange.

I sterilize the 16-ounce or quart (liter) jars for only 1 hour at 15 psi (= 1 kg/cm2), the ½ gallons for 1½ hours, the gallon jars for 2 hours, and the standard spawn bags for 4 hours. The spawn bags featured in this book have a maximum volume of 12,530 milliliters when filled to the brim, although cultivators usually load the spawn bags to ⅓ to ½ capacity. Using the aforementioned formula, each spawn bag weighs 10 pounds (= 4,826 grams). These bags are best inoculated with 200–300 milliliters of fermented, liquid mushroom mycelium using the techniques described further on. Once inoculated, the bags are laid horizontally for the first week and gentling agitated every 3 days with the filter patch topside, until fully colonized. Spawn generated in bags is far easier to use than from jars.

For a comparison of grains, their moisture contents, and kernels sizes, refer to page 43 in The Mushroom Cultivator by Stamets and Chilton (1983). Test batches should be run prior to commercial-scale cycles with sterilization indicator papers. Adjustments in pressure must be made for those more than 3,000 feet above sea level.

Most people create volumetric scoops corresponding to one of the above-mentioned masses. Many cultivators build semiautomatic grain dispenser bins to facilitate the rapid filling of spawn containers. These are similar in design to those seen in many organic food co-ops in North America.

The grain used for spawn production must be free of fungicides, and ideally be organically grown. Grain obtained in the spring was probably harvested 6 or more months earlier. The resident contamination population gradually increases over time. With the proliferation of more contaminants per pound of grain, cultivators will have to adjust their sterilization schedules to compensate. Experienced cultivators are constantly searching for sources of fresh, high-quality grain with endemically low counts of bacteria and mold spores.

With one brand of commercially available rye grain, a cup of dry grain has a mass of 210 grams. Four cups is approximately a liter. Therefore a single petri dish culture can generate from 1 to 5 liters of spawn, utilizing the traditional wedge transfer technique. These techniques are described next.

Filling ½-gallon jars with grain.

First-Generation Grain Spawn Masters

The first time mushroom mycelium is transferred onto grain, that container of spawn is called a grain master, or G¹. The preferred containers for incubating grain masters are traditionally small glass jars or bottles, with narrow mouths to limit exposure to contaminants. Since the grain master is used to generate 100 to 1,000, even 10,000 times its mass, special attention is focused on its purity. Otherwise, the slightest amount of contamination is exponentially expanded with each step, not by a factor of 10, but ultimately by a factor of thousands! Molds have advantages over mushrooms in that within 2 to 4 days, every spore can send up thousands of microscopic tree-like structures called conidiophores on whose branches are dozens of more mold spores. (See The Mushroom Cultivator [1983], Chapter 13.) Mushroom mycelium, on the other hand, typically expands as a linear extension of cells. In a jar holding thousands of kernels of grain, a single kernel of grain contaminated with a mold like Penicillium, surrounded by tens of thousands of kernels impregnated with pure mushroom mycelium, makes the entire container of spawn useless for mushroom culture.

A single 100 × 15-mm petri dish culture can inoculate 4–20 cups of sterilized grain. The traditional transfer method calls for cutting the mushroom mycelium into wedges or squares using a sterilized scalpel. Prior to this activity, the surface space where the transfers are to take place has been aseptically cleaned. The hopeful spawn maker has showered, washed, and adorned newly laundered clothes. Immediately prior to doing any set of inoculations, the cultivator washes his or her hands and then wipes them with 80% rubbing alcohol (isopropanol). If working in front of a laminar flow hood, the freshest, sterilized material is kept upstream, with the mycelium directly downstream. The cultivator prioritizes items on the inoculation table by degree and recentness of sterility. The same attention to movement that was used to inoculate nutrient-filled petri dishes in Chapter 12 is similarly necessary for successful production of grain spawn. Attention to detail, being aware of every minute movement, is again critical to success.

Pressure cooker useful for sterilizing agar and grain media.

Sterilization indicator test strips are placed into a few grain-filled jars to test sterilization. Note the letter “K” appears when sterilization has been achieved.

Grain-filled ½-gallon jars ready for loading into a commercial autoclave.

Cutting mycelium from the nutrient agar medium.

Steps for Generating First-Generation Grain Spawn Masters

Step 1. Visually ascertain the purity of a mushroom culture, selecting a petri dish culture showing greatest vigor. Ideally, this culture should be no more than 2 weeks old, and there should be a margin of uncolonized media along the inside peripheral edge. This uncolonized zone, approximately ½-inch (1.30 cm) in diameter, can tell the cultivator whether or not any viable contaminant spores have recently landed on the media. Once the mycelium has reached the edge of the petri dish, any contaminant spores, should they be present, are dormant and lie invisible upon the mushroom mycelium only to wreak havoc later.

Step 2. Although the contents within may be sterilized, the outer surface of the pressure cooker is likely to be covered with contaminants that can be transferred via hand contact. Therefore, the outside of the pressure cooker should be thoroughly wiped clean prior to the sterilization cycle. Open the pressure cooker in the laboratory clean room. Ideally, the pressure cooker has formed a vacuum in cooling. If the pressure cooker in use does not form a vacuum, outside air will be sucked in, potentially contaminating the recently sterilized jars. The pressure cooker should be placed in the clean room directly after the sterilization cycle and allowed to cool therein. (I usually place a paper towel, saturated with isopropanol, over the vent valve as an extra precaution to filter the air entering the pressure cooker.) Another option is to open the pressure cooker in front of a laminar flow bench at the moment atmospheric pressure is re-achieved. Remove the sterilized grain jars from the pressure cooker. Place the grain-filled jars upstream nearest to the laminar flow filter. Sterilize the scalpel by flaming until red hot.

Step 3. Directly cut into the petri dish culture. (The blade cools instantly on contact.) Drag the blade across the mycelium-covered agar, creating eight or more wedges. Replace the petri dish lid.

Step 4. Loosen the lids of the jars to be inoculated so you can lift them off later with one hand. Re-flame the scalpel. Remove the petri dish cover. Spear two or more wedges simultaneously. Replace the petri dish cover. While moving the wedges of mycelium upstream to the jars, remove the lid of the jar to be inoculated, and thrust the wedges into the sterilized grain. Replace and screw the lid tight. Shake the jar so the wedges move throughout the interior mass of the grain, with the intention that strands of mycelium will tear off onto the contacted grain kernels.

Step 5. Set the inoculated jar of grain onto the shelf and incubate them, undisturbed for several days.

Transferring several squares of mycelium from the nutrified agar medium into sterilized grain.

Inoculating G² gallon jars of sterilized grain from ½ gallon (2-liter) G¹ masters.

Jars furthest downstream are inoculated first and removed.

Step 6. Three days from inoculation, inspect each jar to determine two preconditions: first, recovery of the mycelium, or “leaping off” onto contacted grain kernels; and second, the absence of any competitor molds, yeasts, mites, or bacteria. If these preconditions are satisfied, to the best of your knowledge, continue to the next step.

Step 7. Seven days after inoculation, shake each jar again, provided no competitors are detected. Ten to fourteen days after inoculation, incubated at 75°F (24°C), each jar should be fully colonized with mushroom mycelium. If colonization is not complete 3 to 4 weeks after inoculation, something has probably gone awry with the process. Some of the more common causes of slow colonization include unbalanced moisture content, contaminants, weak strain, residual fungicides in the grain, poor-quality grain, etc.

Spawn at the peak of cell development is the best to use, correlating to about 2 weeks after inoculation. The key concept here: to keep the mycelium running at its maximum potential throughout the spawn generation process. With over-incubation the grain kernels become difficult to break apart. Along the path of cell expansion, it’s important for the myceliated grain kernels to separate so they can be evenly dispersed throughout the next generation of substrates. Over-incubation results in clumping, kernels without structural integrity, and an invitation to disease.

Grain masters are kept at room temperature for a maximum of 4 to 8 weeks from the time of original inoculation, but are best used within a week of full colonization. Some farms refrigerate grain masters until needed. I strongly discourage this practice. If the grain masters are not used within 2 weeks of full colonization, over-incubation may result, slowing of cell divisions, with a corresponding decline in vigor. The rule here: Use it or lose it.

Second-and Third-Generation Grain Spawn

The next generation of spawn jars is denoted as G². Each grain master can inoculate 5 to 20 times its mass. Many start with narrow mouth quart mason jars for grain masters, and use ½-gallon or 2-liter jars for second-generation spawn. (For use of bags as spawn containers, see examples.) Third-generation spawn is typically in bag form and is sold to consumer-growers.

A standard inoculation rate would be 1 quart (liter) grain master to 5½ gallons, in other words, a 1:10 expansion. A diluted inoculation, on the verge of being unsuccessful would be 1 quart grain master to 20½ gallons, in other words, a 1:40 expansion. Exceeding a 1:40 expansion of mycelium is likely to be associated with a >20% failure rate, a percentage unacceptable to any spawn laboratory. Not only can the loss be measured in terms of failure to mature, but also each failed spawn jar is likely to be center stage for releasing thousands of contaminants back into the laboratory. Liquid-inoculation techniques allow a much greater exponent of expansion than the traditional method described here. (See Liquid Inoculation Techniques described in this chapter.)

Step-by-step instructions follow for a classic grain-to-grain inoculation. As before, the cleanest items should be prioritized nearest to the micron filter. Adherence to sterile inoculation techniques should be strictly observed.

Steps for Creating Second- and Third-Generation Grain Spawn

The cultivator has sterilized grain in containers larger than the grain master, i.e., ½-gallon or gallon jars, following the standard procedures already outlined. For every quart grain master, 5½-gallon jars are recommended, essentially a 1:10 expansion.

Step 1. Select a grain master showing even, luxuriant growth. Avoid spawn jars having zones of heavy growth, discoloration, or excess liquid.

Step 2. Using a cleaned rubber tire, carefully slam the jar against it, loosening the grain. If the spawn is overgrown, more forcible shaking is required before the spawn kernels will separate. Do not strike the jar against the palm of your hand! Be careful! This author, at the time of this writing, is recovering from a sliced wrist after a brisk visit to the hospital emergency room, caused by a glass jar shattering on his palm during shaking, requiring multiple stitches.

Step 3. Once the grain master has been shaken, loosen the lids of the jars which will receive the spawn. Remove the lid of the grain master and set it aside. With your favored hand (right), move the grain master upstream to the first jar, hovering inches above it. With your other hand, remove the lid, and hold it in the air. By tilting downward and rotating the grain master counterclockwise, kernels of spawn fall into the awaiting jar. Replace the lid of the jar just inoculated and continue to the next. By the time the tenth jar is inoculated, the spawn jar should be empty. Repeated transfers eventually lead to an even dispersal of spawn each time. Precise measurement is desirable but not absolutely critical with this suggested rate of expansion. However, as one becomes more experienced, inoculation rates achieve a high degree of regularity.

Step 4. Once inoculated, the lids are tightened securely. Each jar is then shaken to evenly disperse the grain master spawn kernels through the sterilized grain. Thorough shaking encourages fast grow-out. As the jars are shaken, note the rotation of the myceliated grain kernels through the jar.

Step 5. Set the second-generation spawn jars upon a shelf or rack in a room maintained at 75°F (24°C). The jars should be spaced at least ½ inch apart. Closely packed jars self-heat and encourage contamination. This spawn producer prefers that the jars incubate at an incline, allowing for more transpiration.

Step 6. After 3 to 4 days, each jar is shaken again. As before, striking the jars against a rubber tire or similar surface can loosen the grain. Grasping each jar firmly, accelerate each jar downward in a spiral, pulling back at the end of each movement. This technique sends the top grain kernels deep into the bottom recesses of the jar, in effect, rotating and mixing the grain mass.

Step 7. In 7 to 10 days, reinspect each jar to determine even dispersal of growth centers. Should some jars show regions of growth and no growth, another shaking is in order. Those showing good dispersion need not be disturbed. Here the discretion of the cultivator plays an important role. If any unusual pungent odors are noticed, or if the grain appears greasy, contamination may be present although not yet clearly visible.

Step 8. By day 14, all the jars should be thoroughly colonized by mycelium. With Oyster, Shiitake, Enokitake, Reishi, and King Stropharia, the mycelium has a grayish white appearance 48 hours before flushing out with bright white mycelium.

Each second-generation spawn jar can be used for inoculating another set of grain jars, for instance, 5 gallon jars containing twice the amount of grain as the ½ gallon containers, in effect another 1:10 expansion. You can use 2½-gallon (10-liter) jars or bags at a similar rate. These would be denoted as G³. Third-generation grain spawn is inoculated in exactly the same fashion as second-generation grain spawn. However, contamination is likely to go unobserved. Some large spawn laboratories successfully generate fourth-generation spawn. However, contamination outbreaks discourage most from pushing this expansion any further. As the mass of sterilized grain is increased within each larger container, anaerobic conditions can more easily prevail, encouraging bacteria. These larger containers require more aeration, a feat that is accomplished with frequent shaking (every 48 to 72 hours), greater filter surface area, and near horizontal incubation. When the large containers are laid horizontally, the surface area of the grain-to-air is maximized, providing better respiration for the mushroom mycelium.

Grain inoculated with mycelium but contaminated with bacteria. Note greasy appearance of grain kernels. Bacterially contaminated grain emits a distinct, unpleasant odor.

Throughout every stage in the grain expansion process, any hint of contamination, especially smell, the texture of the grain, or unusual colorations, should be considered warning signs. The spawn maker soon develops a sixth sense in choosing which spawn jars should be expanded, and which should be avoided. Most spawn producers only select a portion of the spawn inventory for further propagation. The remainder are designated as “terminal,” and are not used for further expansion onto sterilized grain. Unless contaminated, these terminal spawn jars usually are of sufficient quality for inoculating bulk substrates. Of course, the spawn manager can always exercise the option of using first-, second-, or third-generation grain spawn for inoculating sawdust or straw.

In effect, what the spawn maker has accomplished is taking a single petri dish, and in three generations of transfers, created 250 gallons of spawn. A stack of twenty petri dishes can give rise to 5,000 gallons of spawn! This places a whole new perspective on the sheer biological power inherent within a single test tube slant, which can easily inoculate a sleeve of twenty petri dishes. Most laboratories do not fully realize the potential of every culture. In many cases, spawn expansion is terminated at G². Many spawn managers choose not to “chase the optimum.” Few laboratories are large enough to accommodate the end result of the methods described here.

An alternative method for generating spawn is liquid culture. This method saves time and money, and is less susceptible to contamination. These techniques are described further on.

The next step is for each of these third-generation spawn units to inoculate 10 to 20 times its mass in sawdust or straw. See Chapters 16 and 17.

Eleven pounds (5 kg) of grain spawn in 2½-gallon (10- to 11-liter) glass jar and polypropylene bag. Glass jars are reusable, whereas spawn bags are currently not recycled. However, since bags are easier to handle, this form is the most commonly sold to mushroom growers by commercial spawn laboratories.

Autoclavable Spawn Bags

Autoclavable bags have been used by the mushroom industry for nearly 40 years. Primary uses for autoclavable bags are for the incubation of grain and sawdust. Preferences vary widely between cultivators. Flat, non-gussetted bags are popular for incubating grain spawn. The more grain filled into a bag, the greater the danger of poor gas exchange, a major factor leading to contamination. Three-dimensional gusseted bags are used primarily for holding non-supplemented and supplemented sawdust. The proper handling of these bags is critical to their successful use. Bags contacting hot surfaces become elastic, deform, and fail.

Currently the industry uses polypropylene or polymethylpentene bags with and without microporous filters. Over the years, a number of patents have been awarded, some long since expired. The use of plastic bags has had a drastic impact on the way many cultivators generate spawn. Numerous patents have been awarded for bags specifically designed for mushroom culture. The earliest patent I can find is one from 1958 awarded to a French man by the name of Guiochon (U.S. #2,851,821). His cylindrical bag resembles the methods still widely in use by Asian cultivators. In 1963 several patents were awarded in London (#985,763; #1,366,777; and #1,512,050). R. Kitamura and H. Masubagashi received a patent (#4,311,477) for a spawn culture-bag in 1982.²

About a dozen bags are currently available to mushroom cultivators, some borrowed from the hospital supply industry. Cellophane deserves reexamination since it is made from wood cellulose and completely biodegradable. If problems with seam integrity, tensile strength, and heat tolerance could be improved, spawn bags made of this environmentally friendly material could eliminate the widespread use of throwaway plastics. An advantage of cellophane-like materials is that the mushroom mycelium eventually consumes the very bag in which it is incubated.

Gallon jars of third-generation grain spawn incubating.

Grain spawn ready for use. Healthy mycelium is usually tenacious, holding the grain together.

Autoclavable bags are inoculated with grain masters and are second or third generation. Agar-to-grain inoculation from petri dish cultures to bags is awkward and impractical unless liquid-inoculation techniques are employed. (These techniques are fully described later on.) Bags are filled with premoistened grain, and the lips folded closed. Some spawn producers use spring-activated clothespins, paper clips, or plastic tape to hold the folds closed. I prefer to simply press the bags together with flaps folded. As the bags are sterilized, the contents exceed the boiling point of water, and gases are released. If the bags are sealed before loading, explosion or “blow-outs”—holes where live steam vented—is likely.

In the standard 18 × 8 × 5-inch gussetted autoclavable spawn bag featuring a 1-inch filter patch, no more than 3,500 grams of dry grain should be used.³ One All-American 941 pressure cooker can process 50 pounds of dry rye grain in one run. However, the pressure cooker—with its tightly packed contents—should be kept at 15+ psi for at least 4 to 5 hours to ensure even and full sterilization.

If the grain is first boiled or simmered in hot water before filling, even moisture absorption is assured. Excess water collecting at the bottom of the bags often leads to disaster. If this water is reabsorbed back into the media by frequent shaking or by turning the bags so that the excessively moist grain is on top, the cultural environment is soon rebalanced in favor of mycelial growth. Standing water, at any stage in the mushroom cultivation process, encourages competitors. Many spawn producers add 20–30 grams of calcium sulfate to the grain, when dry, to help keep the kernels separated after autoclaving.

After sterilization for 2 hours at 15 to 18 psi, if the bags are separated, or 4 to 5 hours if the bags are tightly packed, the bags are removed and allowed to cool in the pure windstream coming from the laminar flow bench. An alternative is to allow the grain bags to cool within the pressure vessel, provided it is of the type that holds a vacuum.

The use of heat-tolerant plastic bags greatly advanced the practicality of the bulk processing of grain and sawdust. One of the first patents for this innovation was awarded to Guiochon. (U.S. Patent #2,851,821) in 1958.

The vacuum is then “broken” by allowing clean-room air to be sucked in. If the pressure cooker does not hold a vacuum, then it should cool within the sterile laboratory to preserve sterility. In either case, I place a presterilized cotton towel, soaked in alcohol, over the vent cock to act as a filter. For equalizing the pressure in a larger autoclave, air passes directly through a microporous filter into the vessel’s interior.

Once the bags are cooled, unfold them by hand, being careful to only touch the outer surfaces of the plastic. A jar of spawn is selected, shaken, and opened. Using a roll-of-the wrist motion, allow spawn to free-fall into each bag at a recommended rate within a range of 1:10 to 1:20. The bag is then laid down to open into the airstream. The top 2 inches of the bag is positioned over the element of a heat sealer and expanded open, again by only touching the outer surfaces of the plastic. The clean air coming from the laminar flow filter inflates the bag. I gently press on the sides, which further inflates them before sealing. The top arm of the sealer is brought forcibly down, often two or three times in rapid succession, pausing briefly to allow the plastic seam to resolidify. Each bag is squeezed to determine whether the seam is complete and to detect leaks. (Often pinhole leaks can be detected at this stage. Having a roll of plastic packing tape handy, 3–4 inches wide, solves this problem by simply taping over the puncture site.)

If the bags hold their seal with no leaks, shaking each bag should mix through the spawn. This cultivator strives to capture enough air within each bag so that when they are sealed, each bag appears inflated. Inflated bags are much easier to shake and support better mycelial growth than those without a substantial air plenum.

Spawn bags should be set on a shelf, spaced ½ inch or more from each other, to counteract heat generation. After 4 days, each bag should be carefully inspected, laid on a table surface, and rotated to disperse the colonies of mycelium. In another week, a second shake may be necessary to ensure full and even colonization.

The advantages of using bags for processing grain spawn are

• In the limited space of a sterilizer, more grain can be treated using bags than jars.
• Bags, if they break, are not dangerous. Being cut by glass jars is one of the occupational hazards of spawn producers.
• Since the bags are pliable, spawn can be more easily broken up into individual kernels and distributed into the next substrate. The process of spawning is simply easier.

Liquid-Inoculation Techniques

A rainstorm is a form of liquid-inoculation. The earliest fungophile, unwittingly or not, engaged in liquid-inoculation techniques. Every time mushrooms are eaten, cooked or washed, spores are disseminated in liquid form. Nature’s model can be modified for use within the laboratory. Currently several strategies incorporate liquid-inoculation methods. The advantages of liquid-inoculation are the speed of colonization, the purity of spawn, and the ease of handling.

Spore-Mass Inoculation

The ultimate shortcut for culturing mushrooms is via spore-mass/liquid-inoculation directly into bulk substrates. Primarily used in China, this technique works well with Oyster and Shiitake mushrooms but is also applicable to all the mushroom species discussed in this book. In effect, this process parallels the technology of the brewery and pharmaceutical industries in the cultivation of yeasts, Saccharomyces cerevisiae and allies. Large fermentation vessels are filled with sugar broth, inoculated with pure spores, incubated, and aerated via air compressors.

Spore-mass inoculation of sterilized substrates is limited to those species that form mushrooms under totally sterile conditions. (Spores collected from wildly picked mushrooms have too many contaminants.) Those mushrooms that require the presence of microflora, such as the White Button mushroom (Agaricus brunnescens) and the King Stropharia (Stropharia rugosoannulata), are excluded. The key requirement is that the parent mushroom fruits on a sterilized substrate, within a sterile environment, and sporulates abundantly. The following mushrooms are some of those that qualify. All are wood or straw saprophytes.

A practical approach is to first sterilize a half-filled gallon container of wood chips, which is then inoculated with grain spawn. After several weeks of incubation, depending on the species, mushrooms form within the environment of the gallon jar. (Supplementation, for instance, with rice bran, oatmeal, or rye flour, facilitates mushroom formation.) Once mature, the mushrooms are aseptically removed and immersed in sterilized water. Commonly the water is enriched with sugar-based nutrients and trace minerals to encourage rapid spore germination. Millions of spores are washed into the surrounding broth. After vigorous shaking (a few seconds to a few minutes), the spore-enriched liquid is poured off into another sterile container, creating a spore-mass master.

Spores begin to germinate within minutes of contact with water. Immediately upon germination, and as the mycelium grows, respiration cycles engage. Therefore, the liquid broth must be aerated or the mycelium will be stifled. The method most used by the fermentation industry is aeration via oilless compressors pushing air through banks of microporous filters. The air is distributed by a submerged aerating stone, a perforated water propeller, or the turbulence of air bubbles moving upwards, as in a fish aquarium. As the mass of the mycelium increases, and as the filters become clogged with airborne “dust,” pressure is correspondingly increased to achieve the same rate of aeration. The vessels must be continuously vented to exhaust volatile metabolites. The goal is to oxygenate the broth.

Scanning electron micrograph of spores in a frenzied state of germination. Note clamp connection on right.

Each spore-mass master can inoculate 100 times its mass. For instance, if one removes a Shiitake mushroom, 4–5 inches in diameter, from a jar of sterilized sawdust, and then places that mushroom into a gallon of sterilized water, the spore-enriched broth, the spore-mass master can inoculate 100 gallons of nutrified liquid media. The functional range of expansion is 1:25 to 1:200, with a heavier inoculation rate always resulting in faster growth. After 2 to 4 days of fermentation at 75°F (24°C), a second-stage of expansion can occur into enriched sterilized water, resulting in yet another 25- to 200-fold expansion of mycelial mass.

Success of the fermentation process can be checked periodically by streaking .1 milliliter across a sterilized nutrient-filled petri dish and incubating for a few days. (See this image.) Additionally, contaminants can be immediately detected through odor and/or through examination of the liquid sample with a microscope. Any gases produced by bacteria or contaminants are easily recognizable, usually emitting a uniquely sour or musty and sometimes sickeningly sweet scents.

The liquid spore-mass inoculum can be transferred directly onto sterilized substrates such as grain, sawdust, straw, cottonseed hulls, etc. If the liquid-inoculum is sprayed, even colonization occurs. If poured, the liquid-inoculum streams down through the substrate, following the path of least resistance. Unless this substrate is agitated to distribute the mycelium, colonization will be uneven, resulting in failure.

Theoretically, the germination of spores in mass creates multitudes of strains that will compete with one another for nutrients. This has been long accepted as one of the Ten Commandments of Mushroom Culture. Scientists in China, whose knowledge had not been contaminated by such preconceptions first developed spore-mass inoculation techniques to an industrial level. Only recently have Western mycologists recognized that a large community of spore matings behaves quite differently than paired individuals. San Antonio and Hanners (1984) are some of the first Western mycologists to realize that grain spawn of Oyster mushrooms could be effectively created via spore-mass inoculation.

The most aggressive strains out-race the least aggressive strains to capture the intended habitat. Recent studies have shown that these aggressive strains overpower and invade the cellular network of competing strains. Dr. Alan Rayner (1988) in studies at the University of Bath described this form of genetic theft as “non-self fusions” between genetically different mycelial systems within the same species. This ability to adapt has made fungi one of the most successful examples of evolution in the biological arena.

Pressurized vessels in China designed for spore-mass fermentation.

The fermented mycelium is tested for purity by streaking sample droplets across a nutrient-media-filled petri dish. After 48 to 72 hours, pure colonies of mycelium (or contaminants) are easily visible.

Spore-mass fermentation techniques are not yet widely used by North American or European cultivators. Concern for preserving strain stability, lack of experience, equipment, and intellectual conflicts are contributing factors. In mushroom culture, intransigence to new ideas has prevailed, often because the slightest variation from the norm has resulted in expensive failures. Since the health of any economy is based on its diversity, the emergence of organically minded gourmet mushroom growers is creating a fertile intellectual habitat for many innovative technologies.

Expanding mycelial mass using a combination of liquid fermentation and traditional grain-transfer techniques. After fermentation for 3 to 4 days, 100 quart (liter) jars of sterilized grain are liquid-inoculated. These are denoted as G¹ masters. In 7 to 10 days, 1,000 ½-gallon (2-liter) jars are inoculated from the G¹ masters. These are called G². Then, 10,000 G³ gallon jars are inoculated from the G²s. Once grown through, 100,000 bags of sawdust spawn can be generated. Each sawdust bag can be expanded by a factor of 10 into supplemented sawdust, creating 1,000,000 fruiting blocks. At 1–2 pounds of mushrooms per block, more than 1,000,000 pounds of mushrooms can be grown from one petri dish in as short as 80 days depending upon the species and strain.

Liquid-Inoculation Techniques: Mycelial Fragmentation and Fermentation

This method differs from the spore-mass inoculation techniques in that the starting material is dikaryotic mycelium, not spores. In short, the cultivator chops up the mycelium into thousands of tiny fragments using a high-speed blender, allows the mycelium to recover, and transfers dilutions of the broth into jars or bags of sterilized grain. I prefer this technique as it quickly generates high-quality spawn, eliminating several costly steps. Once perfected, most spawn producers find grain-to-grain transfers obsolete. The time not spent shaking the spawn jars frees the cultivator to attend to other chores. Most importantly, high-quality spawn is realized in a fraction of the time than traditional methods. Step-by-step methods are described in detail in the ensuing paragraphs. The ambient air temperature recommended throughout this process is 75°F (24°C).

Step 1. A vigorous, nonsectoring culture incubated in a 100 × 15-millimeter petri dish is selected. This parent culture is subcultured by cutting and transferring 1-centimeter squares from the mother culture to ten blank petri dishes. In effect, ten subcultures are generated. The cultures incubate until the mycelia reaches approximately 1 centimeter from the inside peripheral edge of the petri dish, more or less describing an 80-millimeter diameter mycelial mat.

Step 2. When the cultures have achieved the aforementioned diameter of growth, use the following formula to create a liquid culture media: After mixing and subdividing 750 milliliters of the broth into three 1,500-milliliter Erlenmeyer flasks, the flasks are placed within a pressure cooker and sterilized for 1 to 2 hours at 15 psi (252°F =121°C).⁴

Liquid Culture Media for Wood Decomposers

Place a floating stir bar into each Erlenmeyer flask. The openings should be stuffed tightly with nonabsorbent cotton and covered with aluminum foil. The ingredients do not dissolve. The pH falls between 6.0 and 6.5 when using near-neutral water at makeup.

First, a 1,000-milliliter Eberbach stirrer is filled with 750 milliliters of water and sterilized. Simultaneously, three 1,500-milliliter Erlenmeyer flasks, each containing 750 milliliters of the above concoction, are sterilized. After sterilization, the pressure cooker naturally cools. If your pressure cooker does not form a vacuum upon cooling, then the Eberbach stirrer and the Erlenmeyer flasks must be removed at 1 to 2 psi, before reaching atmospheric pressure. Otherwise, contaminants are drawn in. The slightest mistake with this process could ruin everything that is inoculated downstream in this process. If the pressure cooker does achieve negative pressure, the vacuum must be broken paying careful attention to the path through which air is drawn. The outer surface of the pressure cooker should be wiped clean and placed into the airstream coming from the laminar flow bench. Since the airstream coming from the face of the micron filter is free of airborne particulates, the media remains sterile. Additionally, I like to saturate a sterilized cotton cloth (cotton baby diapers work well) with isopropanol and place it over the vent valve as an additional precaution. When the stopcock is opened, clean air is drawn through the alcohol-saturated cloth. Once the pressure returns to normal, the pressure cooker is opened into the airstream, with the leading edge nearest to the filter. The contents are removed and allowed to cool. The cultivator should always remain conscious of the cleanliness of the surfaces of the pressure cooker, his or her hands, and the countertops upon which items are placed.

Inoculating an Eberbach stirrer with agar wedges of mycelium in airstream of laminar flow hood.

Step 3. Of the ten cultures, the five best are chosen. Any culture showing uneven growth, sectoring, or any abnormality is viewed with suspicion and is excluded. The mycelium from each petri dish is sectioned into quadrants with a heat-sterilized scalpel and aseptically transferred into the now-opened Eberbach stirrer containing the sterilized water. Heat sterilization of the scalpel need only occur once. This is the single step that is most dependent upon the actions of the laboratory technician. Since five cultures are cut and transferred, the slightest mistake at any time will allow contamination to be passed on, thereby jeopardizing the entire run. Should the scalpel touch anything other than the cultured mycelium, it should be resterilized before continuing. Once the transfers are complete, replace the screwtop lid of the Eberbach, carefully adhering to the principles of standard sterile technique.

Step 4. The Eberbach stirrer is placed on the power unit, and stirred in 3-second bursts. (The blender I use rotates at 22,000 rpm.) Pausing for 5 seconds, the surviving chunks of agar fall downward into the blades. Another 3-second burst decimates these pieces. One more 5-second pause is followed by the last 3-second, high-speed stir. In effect, the stirring process has created thousands of chopped strands of mycelium, in short cell chains.

Step 5. The water/mycelium blend is transferred, 250 milliliters at a time in equal proportions, into the three 1,500-milliliter Erlenmeyer flask. A remote syringe, pipette, or liquid pump can be used. Less elaborate is to simply “free-pour” equal volumes of myceliated fluid from the Eberbach into each Erlenmeyer. The nonabsorbent cotton stoppers are, of course, removed and replaced with each pouring, being careful not to allow contact between the cotton stopper and any contaminated surface. Each Erlenmeyer is placed on stir plates or on a shaker table and rotated at 100–200 rpm for 48 to 72 hours. The water broth is continuously stirred to allow transpiration of metabolic gases and for oxygen absorption. The fluid has a milky-brown color and is not translucent. Settling of the heavier components is clearly visible when the stirring process is interrupted.

Upon completion, 3,000 milliliters of mycelium are rendered in liquid form. The hyphae, recovering from the damage of being cut by the spinning blades of the blender, are stimulated into vigorous regrowth. At a point several cells away from the cut ends, nodes form on the cell walls, new buds push out, and begin branching. A vast interconnected fabric of cells, a mycelial network, forms. The branches fork continuously. After 2 to 4 days of regrowth in the nutrient-enriched broth, each Erlenmeyer flask becomes its own universe, hosting thousands of stellar-shaped, three-dimensional colonies of mycelium. (See above.) This is the stage ideal for inoculation into sterilized substrates, especially in the generation of grain spawn masters. Far more bioactive than the same mycelium transferred from the two-dimensional surface plane of a petri dish, each hyphal cluster grows at an accelerated rate.

Actively growing mycelium 6 and 12 hours after inoculation.

If, however, the liquid media is not used at its peak rate of growth, and stirs for more than a week, the colonies lose their independence and coalesce into a clearly visible contiguous mycelial mat. Long mycelial colonies adhere to the interface of the fluid surface and the inside of the flask. Chains of mycelium collect downstream from the direction of rotation. Soon after their appearance, often overnight, the medium becomes translucent and takes on a rich amber color. A large glob of mycelium collects on the surface and can be mechanically retrieved with a pair of tweezers, forceps, or scalpel, if desired. The remaining clear amber fluid contains super-fine satellite colonies and hyphal fragments. By passing the fluid through a microporous filter, the mycelium can be recaptured. This technique is especially attractive for those whose goal is running tests on small batches of mycelium. With many species I have grown, the conversion ratio of sugar/wood to mycelium (dry weight) approaches 20%. This percentage of conversion is nearly 80% biological efficiency, considered good in the commercial cultivation of gourmet mushrooms.

Free-pouring of fermented mushroom mycelium into sterilized grain to create grain spawn masters.

Step 6. Each of the three Erlenmeyer flasks now contains 1,000 milliliters of nutrient- and mycelium-rich broth. At 30 milliliters per transfer, 100 ½-gallon (2-liter) grain-filled jars can be inoculated. Here too, a pipette, a back-filled syringe, burette, or pump can be used.⁵ I prefer “free-pouring” 30–50 milliliters of myceliated broth directly out of each Erlenmeyer into each half gallon jar of sterilized grain. In time, an adept cultivator develops a remarkably accurate ability to dispense liquid spawn in consistently equal proportions. The spawn maker’s movements become rapid, repetitious, and highly rhythmic.

One study, using a similar method (Yang and Yong, 1987), showed that the hyphal clusters averaged less than 2 millimeters in diameter and that each milliliter contained 1,000 to 3,500 “hyphal balls.” The range of time for the maximum production of hyphal clusters varied between species, from 2 days to 14. The recommended inoculation rate was 15 milliliters for each 250 grams of grain. For ease of handling, distribution, and colonization, I find that the dilution schedule described above efficiently inoculates large volumes of grain in the creation of grain masters. (I use 30–50 milliliters of inoculum to inoculate 500–600 grams of grain in 2-liter or ½-gallon jars.) Most of the wood decomposers described in this book flourish with the aforementioned technique. Kawai et al. (1996) showed that, when comparing the effect on liquid fermentation of Shiitake mycelium versus solid spawn, the time to fruiting was sped up by 25%.

The lids to each container are replaced as soon as they are inoculated. If the lids to each jar are loosened prior to free-pouring, then one hand lifts each lid, while the other hand pours the liquefied mycelium into each jar, moving side to side. If an assistant is present, the jars are removed as soon as they are inoculated. As they are removed, each lid is tightly secured; the jar is quickly shaken to evenly mix the liquid spawn through the grain. Each jar is stored at an angle on a spawn rack. One person inoculating in this fashion can keep two people busy “feeding” the inoculator new jars and removing those just inoculated. Since this system is fast paced, the time vector, the “window of vulnerability,” is much less compared to the time-consuming, labor-intensive, traditional methods. The disadvantage of this technique is that the stakes for the clumsy spawn producer are higher. Any mistake will be amplified with force. Should any one of the petri dish cultures harbor contaminants, once those cultures are placed together in the Eberbach stirrer, all resulting spawn jars will be contaminated. This is an all-or-nothing technique. Fortunately, if you are following the techniques outlined in this book, success is the norm.

The jars normally grow out in 4 to 10 days, many times faster than the traditional transfer technique and the jars are only shaken once—at the time of liquid-inoculation. With the traditional wedge-transfer technique, each individual jar must be shaken two or three times to insure full colonization: first at inoculation; second three days hence; and finally at days 5, 6, or 7. Remember, not only is the cultivator gaining efficiency using the liquid-inoculation method, but 100 grain masters are created in a week from a few petri dish cultures! With less need for shaking, hand contact with the grain masters is minimized. Time is conserved. Probability of contamination is reduced. Growth is accelerated. With each kernel, dotted with stellar clusters of hyphae from the first day of inoculation, spawn quality is greatly improved.

As with any method described in this book, quality controls must be run parallel with each procedure. A sample of the mycelium-enriched broth is drop-streaked across the surface of a few nutrient-agar-filled petri dishes. (See this image.) These will later reveal whether the liquid contains one organism—the mycelium—or a polyculture—the mycelium and contaminants. Furthermore, one or more of the sterilized grain-filled jars should be left unopened and uninoculated to determine the success of the sterilization procedure. These “blank” vessels should not spontaneously contaminate. If they do, then either the sterilization time/pressure was insufficient or airborne contamination was introduced, independent of the liquid-fermented spawn. If the jars injected with the fermented mycelium contaminate, and the uninoculated controls do not, then obviously the vector of contamination was related to the act of inoculation, not the cycle of grain sterilization. (See Chapter 10: The Six Vectors of Contamination.)

A space-efficient rack for incubating grain spawn in jars. Three hundred forty ½-gallon jars can be stored on this 8-foot long x 8-foot high x 16-inch wide shelf system. Spawn quality is improved by storing the jars at an angle. Earthquake sensitive.

Pelletized (Granular) Spawn

Trends in spawn technology are evolving towards pelletized spawn. Pelletized spawn is specifically designed to accelerate the colonization process subsequent to inoculation. Examples of pelletized spawn range from a form resembling rabbit food to pumice-like particles. In either case, they are nutrient saturated to encourage a burst of growth upon contact with mushroom mycelium. Pelletized spawn varies in size from 1 millimeter to 5 millimeters in diameter.

Adapting food mills designed for the manufacture of animal feeds can make pelletized spawn. With modest reengineering, these machines can be modified to produce spawn pellets. Idealized spawn seeks a balance between surface area, nutritional content, and gas exchange. (See Yang and Jong, 1987; Xiang, 1991; Romaine and Schlagnhaufer, 1992.) Another simple and inexpensive form of pelletized spawn can be made from vermiculite saturated with a soy-protein-based nutrient broth, a “secret” method used by some of the largest spawn producers.

The key to the success of pelletized spawn is that it enables easy dispersal of mycelium throughout the substrate, quick recovery from the concussion of inoculation, and ideally, the sustained growth of mycelium sufficient to fully colonize the substrate. Many grains are, however, pound-for-pound, particle for particle, more nutritious than most forms of pelletized spawn.

I believe the spawn should be used as the vehicle of supplementation into a semiselective substrate. Others subscribe to the school of thought that the substrate’s base nutrition should be raised to the ideal prior to spawning. The danger with this approach is that, as the base nutrition of the substrate is raised, so too is its receptivity to contaminants. From my experiences, using a nutrition particle already encapsulated by mushroom mycelium is more successful. The ultimate solution may be a hybrid between liquid-inoculum and grain spawn: a semisolid slurry, millimeters in diameter, that would maximally carry water and nutrients, and support the mycelium as it projects hundreds of cells from each inoculation point.

Matching the Spawn with the Substrate: Critical Choices on the Mycelial Path

Once spawn has been created, the cultivator arrives at a critical crossroad in the mushroom cultivation process. Several paths can be pursued for the growing of mushrooms, depending on the species and base materials. Some of these paths are intrinsically unproblematic; others are not. Success is measured by the following criteria: speed and quality of colonization, crop yield, and resistance to disease.

The first step can be the most critical. When trying to match a mushroom strain with an available substrate, I place a small sample of the substrate into the agar media formula. Upon exposure, the mushroom mycelium generates enzymes and acids to break down the proposed food source. Once acclimated, the mycelium now carries a genetic memory of the end substrate to which it is destined. With Shiitake, Enokitake, Maitake, and Reishi, I acquaint the mushroom mycelium with the host substrate by introducing to the media 1- to 2-gram samples of the sawdust directly into the liquid fermentation vessels. This liquid-inoculum is then used to generate grain spawn. I am convinced that this method empowers the mushroom mycelium.

Grain spawn can be used for direct inoculation into pasteurized straw, into sterilized sawdust, or into enriched sawdust. If you are growing Oyster mushrooms, the recommended path is to inoculate straw with grain spawn. If one wants to create plug spawn for the inoculation of stumps and logs, the best path is to go from grain spawn to sterilized sawdust, and once grown out, to sterilized wooden dowels. For the rapid, high-yield methods of growing Shiitake, Enokitake, Maitake, Kuritake, and others indoors on sterilized substrates, I recommend the following path: going from grain spawn to sterilized sawdust to enriched sawdust. Each transfer step results in an expansion of mycelial mass, usually by a factor of 5 to 10 and takes 1 week to 2 weeks to fully colonize.

The tracks recommended in the previous paragraph are the result of thousands of hours of experience. More direct methods can be used, but not without their risks. For instance, one can use grain spawn of Shiitake to inoculate enriched sawdust, skipping the above-described intermediate step of sterilized sawdust. However, several events are observed subsequent to inoculation. First, there are noticeably fewer points of inoculation than if sawdust spawn were used. As a result, recovery is slower and colonization is not as even. (“Leap-off” is faster from sawdust spawn than from grain spawn. The mycelium has already acclimated to the sawdust substrate.) Most importantly, a marked increase in temperature occurs soon after inoculation, known by mushroom cultivators as thermogenesis. By enriching the substrate with grain spawn, increasing its nitrogen content, you accelerate biochemical reactions, and correspondingly, two main by-products: heat and carbon dioxide. Should internal temperatures exceed 100°F (38°C) in the core of each bag, latent contaminants, especially thermophilic bacteria and black pin molds (Aspergillus, Rhizopus, and Mucor) spring forth, contaminating each and every bag. These same bags incubated at 75°F (24°C) would otherwise be successfully colonized with mushroom mycelium. In general, the cultivator should assume that a minor population of contaminants will survive “sterilization” especially as the mass of each batch increases. Thermotolerant contaminants are activated when temperatures within the substrate spiral upwards. To thwart this tragedy, you should space the bags containing nitrogenous supplements well apart, placed on open wire rack shelving. The laboratory manager should carefully monitor air temperature to offset the upwardly spiraling trend in internal temperatures.

This arena of problems is largely avoided by using sawdust spawn for inoculation into supplemented sawdust substrates rather than grain spawn. Thermogenesis is reduced to a more manageable level. Colonization is faster and more even, and one gets more “mycelial mileage” from grain spawn by generating intermediate sawdust spawn. In essence, another exponent of expansion of the mycelial mass has been introduced to the benefit of overall production.

In contrast, grain spawn is preferred over sawdust spawn for the cultivation of Oyster mushroom on cereal straws. Grain spawn boosts the nutritional base of straw, radically improving yields compared to using an equal mass of sawdust spawn. Although sawdust may have more points of inoculation, yields are substantially less than if the straw had been impregnated with grain spawn. Three exceptions are Hypsizygus ulmarius, H. tessulatus, and Pleurotus eryngi, all of which benefit when sawdust spawn is used to inoculate wheat straw. In these cases, yields may be enhanced as the enzymes secreted target the higher lignin components in wood.

In Chapter 21, the growth parameters of each species and the recommended courses for matching spawn and substrate for maximizing yields are described in detail.

Spawn Storage

Spawn can be stored for only a short period of time before a decline in viability occurs. Those who buy spawn from afar are especially at risk. As spawn ages, and with the depletion of food resources, the mycelium’s rate of growth declines. Metabolic wastes accumulate. With the loss of vitality, the mycelium’s anti-disease defensive mechanisms fail. Opportunistic molds, bacteria, viruses, and other microscopic organisms proliferate. Good-quality spawn on day 30 (from the date of inoculation) is less than half as viable at day 60.

Generally, spawn should be used at peak vitality. If it cannot, only one option remains: slowing growth by refrigeration. Spawn can be refrigerated for several weeks at 35–40°F (1.6–4.4°C), effectively slowing its rate of decline, provided the refrigeration process does not, in itself, cause contamination to flourish. Spawn must not be kept in a refrigerator in the same space as mushrooms are stored. Free-floating mushroom spores can become a vehicle of contamination by bacteria and other fungi directly into the stored spawn. Spoiling mushrooms are often covered with the very contaminants so dreaded in the laboratory environment.

Another problem with refrigeration rooms is that the cooling of spawn causes condensation within the spawn containers. The cultivator should always view excess water, in the form of condensation, with concern. Contaminants proliferate within the water droplets and are efficiently spread by them. Bacteria, in particular, reproduce feverishly in free water environments, even at cool temperatures. Further, refrigeration blowers and cooling elements attract and collect dust particles, which inevitably must be cleaned. The force of the air blasting from the cooling elements covers the outer surfaces of the bags with contaminant particles that are easily transferred by anyone handling them. Most often, the filter media, designed to limit airborne contamination, become the sites of black and green mold growth. In time, they can penetrate from the outside into the interior environment of the spawn containers.

Oyster mushrooms “breaking out” of a jar filled with grain spawn.

If refrigeration is the only alternative, then, by definition, you have missed the best opportunity: to use the spawn at its peak of vitality. Nevertheless, every spawn producer faces this dilemma. So, if you have to refrigerate your spawn, the following precautions are suggested:

• Treat the refrigeration room as if it were a clean room. Analyze all potential contamination vectors. Install a HEPA filter if necessary. Make sure floors and walls are kept clean by frequently washing with a 10% bleach solution.
• Rotate your spawn! Only similarly aged spawn should be kept together.
• When refrigerating spawn, use bags, not jars.
• Inspect the stored spawn once a week for visible signs of contamination, especially at the location of the microporous filter patches. (Although spores may not pass through the filtration material, mold mycelia can.)
• Maintain a low relative humidity. The humidity should never exceed 60%, and ideally should be kept at 35–50% range.
• Minimize any material that could become a platform for mold growth, particularly wood, cardboard, and other paper products.

Lastly, some species are more receptive to cold storage than others. Some of the tropical species die upon exposure to cold temperatures. (Volvariella volvacea is one notable example.) The cold-weather Oyster strains (Pleurotus ostreatus and allies) can be shocked into fruiting upon placement into a cold room. One commonly sees Oyster mushrooms fruiting frantically in containers that were otherwise hermetically sealed. The force of fruiting, the bursting forth of mushrooms within the spawn containers, can actually cause enough stress to split plastic seams, unscrew lids on bottles, and force apart filter membranes.

With the rapid-cycle spawn techniques described in this book, cold storage of spawn is not necessary and is not recommended. Cold storage is an option widely utilized by the Agaricus industry, an industry historically fractured into specialty companies. When inventories exceed demand, spawn is kept for as long as possible under refrigeration. Often the consumer, not knowing better, becomes the victim of a spawn producer’s overproduction. If the spawn fails, the excuse heard, more often than not, is that the purchaser mishandled the spawn! This type of business relationship is intrinsically problematic, and is yet another reason why mushroom farms should generate their own spawn.

Sawdust spawn is simply created by inoculating grain spawn onto sterilized sawdust. Hardwood sawdust, especially oak, alder, cottonwood, poplar, ash, elm, sweetgum, beech, birch, and similar woods are best. Fresh sawdust is obviously better than aged, and sawdust with dark zones (often a sign of mold infestation) should be avoided. Sawdust from milling lumber is best because of its consistent particle size, measuring, on average, 1–5 millimeters in diameter. Sawdust from furniture manufacturers is much more difficult to formulate. Often that sawdust is either too fine and/or combined with shavings. This combination results in an inconsistently comprised substrate, difficult to use, difficult to replicate, and poor in its overall suitability as sawdust spawn. With shavings, the mycelium must expend excessive cellular energy to span the chasms between each food particle. Per cubic inch, shavings are too loose a form of wood fiber, insufficient to support a dense mycelial mat let alone a substantial mushroom.

Sawdust is moistened 60–70%, scooped into gusseted polypropylene bags to a gross weight of 6 pounds. The open tops of the bags are folded down and stacked tightly into a square pushcart. This helps the bags form into a cube. Should excess water becomes visible, collecting at the bottom of the bags, then less water is added at makeup. Fortunately, mycelium tolerates a fairly broad range of moisture content for the production of sawdust spawn.

Some spawn producers secure the open flaps of the bags with plastic tape, spring-activated clothespins, or even paper clips. To meet this need, a cultivator-mycologist named Dr. Stoller invented a specialized collar, filter, and lid combination that is still in use today. If the bags are carefully handled, however, many cultivators simply press adjacent bags tightly together, negating the need for fasteners. The bags are loaded into an autoclave or pressure cooker and sterilized for 2 to 3 hours at 15 psi. Upon return to atmospheric pressure, and following the same procedures outlined for cycling grain spawn, the bags are removed from the pressure vessel directly into the clean room.

Each gallon (4 liters) of grain spawn can effectively inoculate ten 5-pound bags of moist sawdust spawn. Exceeding twenty bags of sawdust inoculated per gallon of grain spawn is not recommended. Strict adherence to the sterile techniques previously outlined in this book must be followed during the inoculation process. I recommend washing your hands periodically with antibacterial soap (every 30 minutes) and frequently wiping them with isopropanol (every 10 minutes). Even with surgical gloves, periodic cleaning is recommended. Once inoculations are completed, those with delicate skin should apply a moisturizer to prevent damage from disinfectants.

Step-by-Step Instructions for Inoculating Sawdust

Step 1. Choosing the grain spawn. Grain spawn should be selected from the laboratory inventory. Ideally, spawn should be 1 to 3 weeks of age, at most 4 weeks. Carefully scrutinize the filter disk zone, inside and outside, to discern the presence of any molds or unusual signs of growth. Only cottony spawn, void of wet spots or areas of no colonization, should be chosen. Since the spawn generally chosen is second or third generation, bag spawn is preferred for this stage. Slamming the jar against a cleaned rubber tire loosens the grain kernels of each spawn jar.

Step 2. Retrieving the bags from the autoclave. Bags of sawdust, having been removed directly from the autoclave, cool to room temperature by placing them in the windstream of a laminar flow hood. Once the bags are below 100°F (38°C) inoculations can proceed.

Step 3. Opening the bags. The bags are opened by pulling the outside plastic panels outwards from the outside. The inoculator’s hands never touch the interior surfaces. If they do, contamination is likely. Once ten bags have been fully opened, the inoculator wipes his or her hands with isopropanol, and brings a gallon of grain spawn to the table directly downstream from the newly opened bags. The jar lid is loosened to a point where it can be lifted off easily with one hand.

Step 4. Inoculating the bags in a specific sequence. If using jar spawn, remove the lid and place it upside down, upstream and away from the bags to be inoculated. Since you may wish to return the lid to the spawn jar should all its contents not be used, pay attention to the manner in which it is handled. Grasping the spawn jar with one hand, palm facing up, position the jar opening above the first bag to be inoculated. If you are right-handed, inoculate each sawdust bag in sequence going from left to right. (Left-handers would logically do this in the reverse.) With a roll of the wrist, angle the jar so that grain spawn free-falls into the opened bag. The spawn must be well separated for this technique to result in a consistent rate of inoculation for each bag. Through trial-and-error and experience, a highly rhythmic and exact amount of spawn is approportioned among the ten sawdust bags.

If there were, for instance, four rows of ten bags in front of the laminar flow bench, then a right-handed person would inoculate bags starting from the far left, rear bag. Each bag to the right would then be inoculated until the back row is finished. In turn, the third row would then be inoculated with the next gallon of grain spawn, again from left to right. In this fashion, the hands of the inoculator cannot jeopardize the sanctity of the upstream bags. To inoculate the first row nearest the face of the micron filter would endanger downstream bags from the debris coming from the inoculator’s hands and/or undetected contaminants from a spawn jar.

Step 5. Sealing the sawdust spawn bags. Few steps are as critical as this one. The simple mechanical act of sealing sterile airflow bags can have extraordinarily disparate results for the spawn incubation process. All other steps in this process can be perfectly executed, and yet failure to achieve a continuous seal can be disastrous.

Sawdust spawn of Reishi (Ganoderma lucidum). Note inflated atmosphere within bag.

I attempt to create a positively inflated bag at the time of sealing, to create a positive-pressurized bubble-like environment. (See example.) Although the filter patch allows the transpiration of gases, it is not at a rate that causes the bag to noticeably deflate, even with gentle squeezing. When this bubble environment is created at the time of sealing, two advantages are clearly gained. First, the grain spawn mixes and rotates easily through the sawdust, making shaking easy. Second, each bag now has a voluminous plenum, a mini-biosphere with an atmosphere nearly matching the volume of the sawdust. At least 25% air space should be allotted per spawn bag; otherwise anaerobic activity will be encouraged.

The open bag is laid horizontally, with its opening overhanging the heating element. Grasping both the left and right outside surfaces, the bag is pulled open to fill with the sterile wind. A “Spock-like” finger position keeps the bag maximally inflated while the heat sealer joins the plastic. Two strokes are often necessary for a continuous seal. By gradually increasing the duration of the seal, an ideal temperature/time combination can be found. Since the plastic liquefies upon contact with the heating element, the bags should not be squeezed during sealing.

Pinholes or small tears cause the bags to collapse. Collapsed bags contaminate with alarming frequency. A simple test determines if the problem is at the seal or not. Roll the sealed region several times into a tight fold and push down. The bag inflates and if there is a leak not at the seal, a distinct hissing sound emanates from the defective site. Should the bag remain tightly inflated with no apparent loss of pressure, then the seal at the top is at fault. Simply reseal and test again for leaks.

Step 6. Shaking the sawdust spawn bags. Once the bags have been properly sealed, they are thoroughly shaken to evenly distribute the spawn kernels. If partially inflated, this process takes only a few seconds. Proper shaking is critical for successful spawn incubation. (See example.)

Hand in position used for opening bags, lifting petri dish lids, and removing spawn jar caps.

Step 7. Incubating the sawdust spawn bags. Unlike nutrified sawdust, most sawdust bags contacting each other during incubation grow out without contamination. Even so, I still recommend an air space for heat dispersal. The laboratory space can be maximized with sawdust spawn. By placing a small thermometer between the two faces of the touching bags, the laboratory manager can track temperatures to be sure they do not stray into the danger zone of >95°F (35°C). Above this temperature, thermophilic fungi and bacteria reign. In a burgeoning laboratory where space is limited, cultivators tend to place bags close together, which can start a dangerous cycle of self-heating. Bags should be spaced an inch or two apart to offset this temperature spiral.

In 3 days, recovery from the concussion of inoculation is clearly visible from the grain kernels. The kernels become surrounded by fuzzy mycelium. Looking at a population of bags on a shelf from afar quickly tells the laboratory manager how even the spawn run is. Concentrated pockets of growth, adjacent to vast regions of no growth, result in poor completion. If evenly inoculated, the sawdust spawn is ready to use within 2 weeks.

Sawdust spawn is used for one of five purposes:

• To sell to log growers as spawn
• To inoculate outdoor beds by dispersing the spawn or by burying the mass into the sandy soils
• To inoculate sterilized hardwood dowels in the creation of plug spawn for log and stump growers
• To grow mushrooms on (However, most of the species described in this book benefit from having the sawdust enriched with a readily available, nitrogenous supplement such as bran.)
• To inoculate 5 to 20 times more sterilized enriched sawdust, usually sawdust supplemented with nitrogenous bran, soybean flour, etc.

Inoculating sawdust with grain spawn.

Sealing the bag of sawdust after inoculation with grain spawn.

Dispersing the spawn throughout the sawdust by shaking. The inflated bag not only facilitates shaking, but also provides a sufficient atmospheric plenum within each bag, accelerating the growth of the mushroom mycelium.

When sawdust is supplemented with a nitrogen-rich additive, the yields of most wood-decomposers are enhanced substantially. Rice bran is the preferred additive in Asia. Most brans derived from cereal grains work equally well. Rye, wheat, corn, oat, and soybean brans are commonly used. Flours lack the outer seed coat, and by weight have proportionately more nutrition than brans. Other more concentrated nitrogen sources such as yeast, soy oil, and peptone require precise handling and mixing at rates more dilute than bran supplements. Less is used in formulating the substrate. The nutritional tables in Appendix 5 will help cultivators devise and refine formulas. Mini-trials should be conducted to prove suitability prior to any large-scale endeavor.

For the cultivation of Shiitake (Lentinula edodes), Enokitake (Flammulina velutipes), Maitake (Grifola frondosa), Kuritake (Hypholoma sublateritium), Lion’s Mane (Hericium erinaceus), the Black Poplar (Agrocybe aegerita), King Oyster (Pleurotus eryngii), Tuber Oyster (Pleurotus tuberregium), Nameko (Pholiota nameko), and many other wood-loving species, the following formula is recommended. Alterations to the formula will further enhance yields for each strain. I find this formula to be highly productive and recommend it highly.

The base substrate is composed of a fast-decomposing hardwood, such as alder, poplar, and cottonwood, in contrast to the slow-rotting woods like oak and ironwood. If these types of quick-rotting woods are unavailable, deferment should first be made to the tree types upon which the mushroom species natively inhabits. Most of the photographs in this book are from blocks made with this basic formula.

I have devised the following fruiting formula utilizing hardwood sawdust, hardwood chips, and a nitrogen-rich supplement, in this case, oat bran. Water is added until 65–75% moisture is achieved, a few percentage points below saturation.

Components for the fruiting formula: sawdust, chips, and bran.

Adding the supplement (rice bran) to hardwood sawdust.

The Supplemented Sawdust “Fruiting” Formula: Creating the Production Block

This formulation is designed for maximizing yields of wood decomposers. Most gourmet and medicinal mushrooms produce prolifically on this substrate. If wood is a scarce commodity and not available as a base component, please refer to Chapter 18.

The Sawdust/Bran Fruiting Formula

By dry weight, the fraction of bran is approximately 20% of the total mass. By volume this formula is equivalent to

The above-mentioned mixture fills 160 to 180 bags of moist sawdust/bran to a wet mass between 5.0 and 5.5 pounds. By using larger chips mixed with sawdust, aeration increases, metabolism is accelerated, and yields are enhanced. Royce (2000) noted that when sawdust less than .85 mm was removed from the mix, yields were enhanced. I recommend using a standardized volumetric unit for ease of handling, anything from a plastic 4-gallon bucket to the scoop bucket of a front-end loader. In either case, simply scale up or down the aforementioned proportions to meet individual needs. Thorough mixing is essential.

Adding 2- to 3-inch diameter wood chips on top, which builds the matrix.

The ingredients are thoroughly mixed.

The above weights of the sawdust and chips are approximate, based on their ambient, air-dried state. (The wood used, in this case, is red alder, Alnus rubra, and is highly recommended.) Bran should be stored indoors, away from moisture, off the ground, to prevent souring. (Rice bran readily contaminates and must be carefully handled. Molds and bacteria flourish in most nitrogen-rich supplements soon after milling and exposure to moisture.)

Using a 4-gallon bucket as a measurement unit, 16 buckets sawdust, 8 buckets chips, and 2 buckets bran lie ready for use. All three are mixed thoroughly together in dry form, then gypsum is added, and the final mixture is moistened to 60–65%. This formula makes 70 to 80 bags weighing 5.5 pounds. Directly after makeup the bags are loaded into the autoclave for sterilization. Should the mixture sit for more than a few hours, fermentation reactions begin. Once bacteria and molds flourish, the mixture is rendered unsuitable.

If alder is unavailable, I strongly encourage substituting other rapidly decomposing hardwoods, such as cottonwood, poplar, willow, aspen, sweetgum, and similar wood types from riparian ecosystems. Although oak is the wood most widely used in the cultivation of Shiitake, Maitake, and Enokitake, its inherent, slower rate of decomposition sets back fruiting schedules compared to the above-mentioned hardwoods. Sycamore, mahogany, ironwood, the fruit trees, and other denser woods require a longer gestation period, although subsequent fruitings may benefit from the increased wood density.² (Kruger, 1992) Here, a little experimentation on the part of the cultivator could have far-reaching, profound results. Mini-trials matching the strain with the wood type must be conducted before expanding into commercial cultivation.

By laying out sawdust first in a 10 × 10-foot square, the chips can be thrown evenly upon the sawdust, and topped by broadcasting of bran evenly over the top. This mass is mixed thoroughly together by whatever means available (flat shovel, cement or soil mixer, tractor). A mixer of less than a cubic yard in capacity is probably not more efficient than one person mixing these three ingredients by hand with a shovel. Pockets of discoloration, mold, or “clumps” should be avoided during the making up of this composition. The more competitors at makeup mean the more that are likely to survive the “sterilization” cycle.

Mixing the above components by hand becomes functionally impractical beyond 300 bags per day. At this level of production and above, automated mixing machines and bag fillers, adapted from the packaging and nursery industry, are far more efficient in terms of both time and money invested.

Three times the formula featured earlier in this chapter created 210 6-pound (< 3 kg) bags of the fruiting formula. Once mixed and wetted, this mixture must be immediately loaded into the autoclave and sterilized.

Testing For Moisture Content

Wetting the substrate to its proper moisture content is critical to creating a habitat that encourages mycelial growth while retarding contamination. If too much water is added, exceeding the carrying capacity of the media, the excess collects at the bottoms of the bags, discouraging mycelium and stimulating bacterial blooms and anaerobic activities. Ideally, sawdust is wetted to 60–65% water. If the wetted mix can be squeezed with force by hand and water droplets fall out as a stream, then the mix is probably too wet.

The easiest way to determine moisture content is by gathering a wet sample of the mixture, weighing it, and then drying the same sample in an oven for 1 hour at 350°F (180°C). If, for instance, your sample weighed 100 grams before drying, and only 40 grams after drying, then obviously 60 grams of water were lost. The moisture content was 60%.

Once the person making the substrate obtains experience with making up a properly balanced substrate, moisture content can be fairly accurately determined by touch. Materials are measured volumetrically, correlated to weights, for ease of handling. This ensures that the mixing proceeds with speed and without unnecessary interruption.

Commercial double-door autoclave.

Choosing a Sterilizer, aka Retort or Autoclave

Although home-style pressure cookers are ideal for sterilizing agar media and for small-to-medium batches of grain, they have insufficient capacity for the sterilization of bulk substrates. The problems faced by the mushroom cultivator in Thailand or the United States are the essentially the same. In developing countries, the sterilizer is often a makeshift, vertical drum, heated by fire or gas. A heavy lid is placed on top to keep the contents contained. The boiling of water generates steam, which over many hours will sufficiently “sterilize” the substrate. This method works well within the model of many rural agricultural communities.

The pressurized steam autoclave is far better suited for commercial production. The most useful autoclaves for sterilizing bulk substrates are horizontal and have two doors. Since the autoclave is the centerpiece upon which the entire production process is dependent, many factors must be considered in its acquisition: size, configuration, and placement. Another important feature is its ability to hold a vacuum subsequent to the sterilization cycle. If the autoclave cannot hold a vacuum as it cools, a valve should be installed for the controlled intake of filtered air. If the influx of air is not filtered, the contents can contaminate after sterilization.

Hospital autoclaves are typically made of stainless steel and equipped with a pressurized steam jacket. These types of autoclaves are usually smaller than those needed by commercial mushroom cultivators, measuring only 2 × 3 feet or 3 × 4 feet by 3 × 6 feet deep. Furthermore, they usually have only one door, and their pressure ratings have been engineered to operate at 100 psi, far exceeding the needs of most mushroom growers. Unless obtained on the surplus market for a fraction of their original cost, most knowledgeable spawn producers avoid these types of autoclaves. The most cost-effective vessels are those developed for the canning industries. These are commonly called “retorts” and are constructed of steel pipe, ¼ to ⅜ inch thick, and ideally fitted with doors at both ends. The doors come in a variety of configurations. Quick-opening, spider doors are popular and durable. Wing-nut, knock-off latches secure the doors that are slower to open and close. With autoclaves longer than 6 feet, steam spreader pipes are needed so that the entire mass heats up evenly. More suggestions follow for choosing an autoclave:

Recommendations for Equipping an Autoclave:

• Double-doors (i.e., doors at both ends)
• Redundant pressure/temperature gauges (at least two)
• Pressure/Vacuum Gauge (+50 psi to –50 psi) with valves
• Electrical safety interlocks with warning lights
• Hand-operated vent valve on top of autoclave for venting cold air
• 25 psi and 50 psi excess-pressure relief, safety blowout valves
• Hand-operated drain valve for drawing off condensate
• Coating of heat-resistant, anti-corrosive paint
• At least four 1-inch, and/or two 2-inch ports for inputs, exhausts, and sensors
• One-way gate valve in series with a vacuum gauge that allows the drawing in of clean-room air post autoclaving

Recommendations for the Placement of the Autoclave

• Recessed “wells” (2 feet × 3 feet × 2 inches) underneath each door with sealable drains for removing excess condensate from the autoclave after opening
• Insulation jacket (R = 8 to R = 16)
• Length of autoclave framed in its own insulated room (R = 18 to R = 32) with active exhaust (500+ CFM)—fan activated by remote reading thermostat can redistribute excess heat to other environments, if needed
• One door of autoclave opening into clean room—fill side end of autoclave open to outside environment in moderate climates, or under protected overhang in severe climates, allowing for easy cleaning
• Escape doors remote from the door seals of the autoclave should metal fatigue suddenly release an impassable curtain of steam

Sterilization of Supplemented Substrates

Once the bags are filled, the supplemented (sawdust) substrate must be heat-treated for an extended period of time before inoculations can proceed. In a small pressure cooker, 2 to 3 hours exposure to high pressure steam at 15 psi (1 kg/cm²) or 252°F (121°C) usually suffices for sterilizing supplemented sawdust substrates. When sterilizing more than 100 bags in a large pressure vessel, however, the thermodynamics of the entire mass must be carefully considered in choosing a successful sterilization protocol. Hundreds of bags tightly packed in an autoclave achieve different degrees of sterilization. When bags are stacked against one another, the entire mass heats up unevenly. Even so, this practice is common with those whose autoclaves must be packed to capacity in order to meet production requirements. I recommend a two-inch plenum between vertical rows of stacked bags to enhance heat penetration. Bear in mind that sawdust has high insulating properties, making heat penetration through it difficult.

Other factors affect the minimum duration of sterilization. The substrate mixture should be wetted just prior to filling. If water is added to the formula and allowed to sit for more than 6 hours, legions of contaminants spring to life. The more contaminants at makeup, the more that are likely to survive the “sterilization” cycle.

Fresh hardwood sawdust needs 2 to 3 hours of sterilization at 15 psi (1 kg/cm²). The same mass of sawdust supplemented with rice bran needs 4 to 5 hours of sterilization. Hence, one of the cardinal rules of mushroom culture: As the percentage of nitrogen-supplements increases relative to the base substrate, the greater the likelihood of contamination, and thus the greater the need for full and thorough sterilization.

I prefer the aforementioned formula using alder sawdust, alder chips, and oat bran. An autoclave filled tightly 5 bags high, 6 bags wide, and 8 bags deep (240 bags) requires exposure to steam pressure for 8 hours at 15 psi to assure full sterilization. The lower, central core is the slowest to heat up. (See illustration.) By placing, heat-sensitive “sterilization indicator strips” throughout the mass of sawdust-filled bags, a profile of sterilization can be outlined. Each cultivator must learn the intricacies of their system. The combination of variables is too complex to allow universal judgments. Each cultivator must fine-tune his or her techniques. Even the type of wood being used can influence the duration of the sterilization cycle. Woods of higher density, such as oak, have greater thermal inertia per scoop than, say, alder. Each run through the autoclave is uniquely affected by changes in the substrate formulation.

Those with ample space in their autoclaves separate the layers so thermal penetration is uniform. This is ideal. The sterilization cycle can be shortened, again best reaffirmed by sterilization sensitive markers. However, few individuals find themselves in the luxurious position of having an autoclave capable of running several hundred bags with 1 or 2 inches of separation between the layers of bags. These 1 or 2 inches could be used to increase the capacity of the run by approximately 20%. Many small-scale cultivators are soon forced to maximum capacity as their production expands with market demand. In the long run, dense packing is generally more cost efficient compared to loose packing. Hence dense packing, although not the best method, is usually the norm, not the exception with the small to midsized cultivator. Thus, the manager of the autoclave cycle operates from a precarious decision-making position, constantly juxtaposing the needs of production versus the dangers of uneven sterilization due to heavy loading.

Packing an autoclave deeper than four bags (32 inches deep) runs other contradictory risks. In the attempt to achieve full colonization, sterilization time is typically extended, potentially causing other problems: oversterilization of the outer zones and bag fatigue. Oversterilization usually occurs when wood substrates are subjected to steam pressure (15 to 18 psi) for more than 10 hours. The sawdust takes on a dark brown color, has a distinctly different odor signature, and, most importantly, resists decomposition by mushroom mycelium. Prolonged steam sterilization results in complex chemical transformations. (I have yet to find a chemist who can adequately explain what happens from prolonged exposure.) Suffice to say that turpentines, changes in volatile oils, and toxic by-products are responsible for this radical shift in sawdust’s myco-receptivity. In the end, the substrate is rendered entirely inhospitable to mushroom mycelium.

After the autoclave has been packed, the displacement of the cold air by introducing steam and top venting is absolutely critical. The cold air, if not vented, gives a false temperature/pressure reading. At 15 psi, the temperature within the autoclave should be 252°F (121°C). This arithmetic relationship between temperature and pressure is known as Boyle’s Law. When a cold mass is introduced into an autoclave or pressure cooker, Boyle’s Law does not come into play until the thermal inertia of the affected mass is overcome. In other words, as hot steam is being forcibly injected into the vessel, a lag time ensues as the heat is being absorbed by the cold mass, giving a false pressure/temperature reading. Eventually, thermal inertia is soon overcome, and Boyle’s Law becomes operative.

Many autoclaves not only have a combined pressure/temperature gauge but also sport a separate, remote bulb sensor that records temperature deep within the autoclaved mass. This combination enables the laboratory personnel to compare readings between the two gauges. The duration of the autoclave run should not be timed until these differentials have been largely eliminated. (A differential of 10°F should be considered negligible.) In real terms, the differential is normally eliminated within 2 hours of start-up. Obviously smaller vessels have reduced differentials while the most massive autoclaves have substantial contradictions between pressure and temperature readings. Since the duration of “sterilization” is critical, careful consideration of these temperature trends cannot be underemphasized. Cultivators often mistakenly believe the mass has been autoclaved sufficiently when only partial sterilization has been effected. Discarding several hundred bags due to insufficient sterilization is a strong incentive for cultivators to understand the nuances of autoclave cycling. Redundant gauges are recommended since these types of devices repeatedly fail over time.

Four profiles depicting the degrees of sterilization as affected by the method of packing the bags into the autoclave. Note central, lower core is most resistant to deep steam penetration.

A microporous filter canister is attached to a pipe equipped with a gate valve that in turn is connected to a one-way check valve leading directly into the autoclave. Located on the clean-room side, this design allows pressure to be equalized in the autoclave after the sterilization cycle without introducing contaminants.

Post-Autoclaving

When the steam supply to the autoclave is cut off, pressure and temperature precipitously decline. Ideally, your autoclave should achieve a vacuum as it cools. If your autoclave or steam box does not have a tight seal and cannot form a vacuum, provisions must be made so that the air drawn in is free of airborne contamination. This usually means the timely opening of the autoclave into the clean-room air just as atmospheric pressure is attained. Commonly, an autoclave can swing in pressure from 20 psi to –20 psi several hours after steam injection has stopped. This radical fluctuation in pressure further enhances the quality of the sterilization cycle. A 40-psi pressure swing is devastating at the cellular level, disabling any surviving endospores of bacteria or conidia of contaminating molds.

A portable laminar flow wall creates a localized clean zone in which newly autoclaved substrate can safely cool without danger of contamination.

Unloading the Autoclave

Once the autoclave has achieved a vacuum, the pressure must be returned to atmospheric before the door can be opened. Ideally, a gate valve has been installed on the clean room side, on a pipe connected to the combination pressure/vacuum gauge. A microporous filter canister can be attached for further insurance that the rush of air into the autoclave does not introduce contaminant spores. (See illustration.) When the pressure has equalized, the next step is to open the drain valve to draw off excess condensate, which often can be several gallons. After a few minutes, the autoclave door on the clean-room side can be opened.

If the mass has just been autoclaved, the containers will be too hot to unload by hand unless protective gloves are worn. With the door ajar, several hours of cooling are necessary before the bags can be handled freely. Bear in mind that, as the mass cools, air is being drawn in. If that air is full of dust, contamination is likely. I like to thoroughly clean my laboratory while the autoclave is running. I remove any suspicious cultures, vacuum and mop the floors, and wipe the countertops with alcohol. In a separate pressure cooker, I autoclave towels, extra water, and other equipment essential to the impending inoculation cycle. Selected personnel for laboratory work adorn laboratory garments or freshly laundered clothes.

Many spawn producers autoclave on one day, allow the vessel to cool overnight, and open the vessel the next morning. Depending on the mass of the autoclaved material, 12 to 24 hours may pass before the internal temperatures have fallen below 100°F (38°C), the minimum plateau for successful inoculations. Some of the better-equipped spawn producers have large laminar flow hoods, even laminar flow “walls” in whose airstream the sterilized mass is rapidly cooled prior to inoculation.

Profile of atmospheric steam sterilization, also known as super-pasteurization, an alternative method for sterilizing sawdust-based substrates.

Atmospheric Steam Sterilization of Sawdust Substrates

Many cultivators cannot afford nor have access to large-production-style autoclaves. The size of the sterilization vessel is the primary limiting factor preventing home cultivators from becoming large-scale producers. Fortunately, alternative methods are available. Whereas straw is pasteurized for 1 to 2 hours at 160°F (70°C), supplemented sawdust is sterilized only when exposed to steam for a prolonged period of time. Many cultivators retrofit the cargo-style containers used in shipping in a fashion similar to a Phase II chamber. Large-capacity commercial laundry washers, cement mixers, cheese-making vats, beer fermentation vessels, railroad cars, semi-truck trailers, grain hoppers, and even large-diameter galvanized drain pipe can be retrofitted into functional steam chambers for the bulk processing of wood or straw-like substrates.

Once filled to capacity with bags of supplemented sawdust, steam is forcibly injected bringing the mass of the substrate to 190°F (90°C) for a minimum of 12 hours. Since water boils at 212°F (100°C) at sea level, the mass of sawdust cannot be elevated beyond 212°F unless the pressure within the vessel is raised above 1 psi. I call this method atmospheric sterilization or super-pasteurization.

Most competitor organisms are easily killed with steam heat, with the exception of some thermotolerant black pin molds and endospore-forming bacteria. Every microcosm, every microscopic niche, must be subjected to 250°F (121°C) for at least 15 minutes to effect true sterilization. When processing tons of sawdust, true sterilization is rarely achieved. The cultivator must constantly compromise the ideal in favor of the practical. To this end, temperature-sensitive indicator strips help the cultivator determine sterilization profiles. If sawdust is treated in bulk and not separated into individual bags, the danger of cross-contamination is likely during the unloading and spawning process.

After 12 hours of heat-treatment, the steam is shut off. As the mass cools, air will be drawn into the sawdust. The cultivator must take precautions so that contaminants are not introduced. The best alternative is to design the inoculation room with a positive-pressurized HEPA filtration system. Many cultivators use bags or bottles fitted with a filter—either plugged cotton or a specially designed filter disk that prevents the introduction of airborne contaminants. Oftentimes, 1 to 2 days must pass until the mass naturally falls below 100°F (38°C), at which time inoculations can begin.

Super-pasteurization of supplemented oak sawdust substrates, although effective, often results in less total yield than from the same substrate sterilized. Comparative studies by Badham (1988) showed that there are no appreciable differences in yields of Shiitake between supplemented sawdust blocks subjected to high-pressure autoclaving versus atmospheric steam sterilization for the first flush. In the comparison of total yields, however, more mushrooms can be grown per pound of sawdust if pressure sterilization is employed. The greater yield from sterilized sawdust, according to Royse et al. (1985), is not due to the survival of contaminants, but a function of the rendering of the sawdust into a form more readily digestible to the Shiitake mycelium.³ Pressurized steam essentially softens the sawdust.

Sawdust can be just as easily oversterilized when subjected to pressurized steam for prolonged periods. In tightly packed autoclaves, the outer layers can become oversterilized while the inner core can remain understerilized. Spacing the bags apart so even steam penetration occurs offsets this effect. The cultivator must walk a narrow line in choosing the proper combinations of steam, pressure, duration of treatment, and most importantly, density of fill. Beginning cultivators often see more failure than success for the first several production runs until these parameters can be more specifically refined.

Bags of Shiitake mycelia incubating on sterilized sawdust. Note that bags are narrowly separated, but are not touching, which aids in the loss of heat.

Inoculation of Supplemented Sawdust: Creating the Production Block

The best path for the inoculation of supplemented sawdust is via sawdust spawn. However, the direct path of grain spawn-to-supplemented sawdust is also successful, provided several precautions are taken. Inoculations of supplemented sawdust via grain spawn are prone to self-heating, a phenomenon leading to contamination. This is especially true with Shiitake. As supplemented sawdust is consumed by the mycelium of Lion’s Mane, Enokitake, Maitake, Nameko, and the Black Poplar mushroom, exothermic reactions emerge at various rates. Regardless of the species, the incubating bags must be spaced apart to preclude thermogenesis. (Open wire shelves are recommended over solid shelves.) Once inoculated, the internal temperatures of the bags soon climb more than 20°F over the ambient air temperature of the laboratory. Once the 95–100°F (35–38°C) temperature threshold is surpassed, dormant thermophiles spring to life, threatening the mushroom mycelium’s hold on the substrate. For cultivators in warm climates, these temperature spirals may be difficult to control.

Since the risk of contamination is greater with supplemented sawdust, each step must be executed with acute attention to detail. The lab personnel must work as a well-coordinated team. The slightest failure by any individual makes the efforts of others useless. The same general guidelines previously described for the inoculation of sterilized agar, grain, and sawdust media parallel the inoculation steps necessary for inoculating sawdust bran.

Automatic inoculation machines have been built in the attempt to eliminate the “human factor” in causing contamination during inoculation. I have yet to see a fully automatic spawning machine that out-performs a highly skilled crew. When the human factor is removed from this process, a valuable channel of information is lost. The human factor steers the course of inoculation and allows quick response to every set of circumstances. Every unit of spawn is sensed for any sign of impurity or undesirability. The spawn manager develops a ken for choosing spawn based as much on intuition, as on appearance, fragrance, and mycelial integrity.

Inoculations by hand require that either gloves are worn or that hands are washed frequently. With repetition, manual dexterity develops, and success rates in inoculations improve dramatically. Answering the telephone, touching your eyes, picking up a scalpel off the floor, and making contact with another person are causes for immediate remedial action.

Although one person alone can inoculate the sawdust bran bags, a well-coordinated team of three to four expedites the process with the shortest intervals of “down time” and the highest outflow of production. The process can be further accelerated by premarking bags, preshaking spawn, using agitators to evenly disperse the spawn, using gravity or belt conveyors, etc.

Shiitake mycelia on supplemented sawdust one week, three weeks, and six weeks after inoculation.

Steps and Duties for the Personnel Inoculating Supplemented Sawdust

Before proceeding, the lab must be thoroughly cleaned after the autoclave is emptied. The enriched sawdust blocks are positioned in front of the laminar flow bench. Additional blocks are stacked on movable pushcarts that can be quickly moved and unloaded in and out of the inoculation area. The laboratory personnel have prepared the inoculation site by supplying alcohol squirt bottles, paper towels, and garbage bags, marking pens, and drinking water. If only a two-person lab crew is available, the duties of the Lab Manager and the First Assistant are often combined.

Step 1

Lab Manager

Select pure spawn. Avoid any units of spawn showing the slightest disparity in growth. Be suspicious of spawn units adjacent to partially contaminated ones. Usually contamination outbreaks run through a series of consecutive inoculations, to greater and lesser degrees. Individual units of spawn that look pure, but are neighbors to contaminated units, should only be used as a last recourse. Shake the spawn, thoroughly breaking it up into its finest particles. Place the spawn immediately downstream from the bag sealer. Wipe your hands with 80% isopropanol (rubbing alcohol).

First Assistant

The First Assistant works with the Lab Manager in shaking the spawn, readying it for use.

Second Assistant

The Second Assistant positions the bags and begins prelabeling. If more than one strain or species is used, prelabeling must be done carefully, lest confusion between strains occur.

Cutting a bag of pure sawdust spawn for use as inoculum into supplemented sawdust.

Step 2

Lab Manager

The Lab Manager holds a bag of sawdust spawn and, using a pair of aseptically cleaned scissors, cuts at a 45-degree upward angle towards the opposite corner, cutting across the previous seal. (See this image.) This results in a “spout,” facilitating the transfer of spawn from one bag to another. If you hold a bottom corner with one hand and raise the bag with the other, grasping above the newly created spout, the transferring of spawn from one bag to another container is simple and fast. (If inoculating supplemented sawdust with grain spawn, follow these techniques for Inoculating Sterilized Sawdust.)

Pouring sawdust spawn into bag of sterilized, supplemented sawdust.

As the inoculations progress, care is taken not to touch the inside walls of the bags with your hands. The bags can be pulled apart by grasping the outside plastic, expanding the opening, so that sawdust spawn can be received without hindrance. At times the First Assistant may be called upon to make sure the bags are fully opened.

First Assistant

The First Assistant closes the bags on the precleaned thermal bag sealer on the uppermost, opened portion. The sealer is activated (depending on type) and the panels of plastic meld together, capturing a volume of air in the process. Ideally, a “domed” bag can be created. (See this image.) Sometimes, multiple seals are necessary before full closure is achieved.

Second Assistant

As soon as the bag has been hermetically sealed, it is removed from the position behind the sealer and passed to the Second Assistant. The Second Assistant first ascertains the bag has been sealed. With gentle squeezing, leaks are detected by either the slow collapse of the bag, the sound of air escaping, or visual observation. (If the leak still can not be detected, I bring the bag to my face. When squeezing, my face can usually find the location of the hole as a jet of air escapes.) If the leak is due to a puncture, the hole is covered with plastic packaging tape. If the seal is imperfect, the bag is returned to the First Assistant for a second try at heat sealing. Once each bag has been properly sealed and assured of proper labeling, thorough shaking is in order. Using a combination of agitation and rotation, the sawdust spawn is mixed through the supplemented sawdust. The sawdust spawn has a lighter color than the supplemented sawdust and hence it is easy to see when the spawn has been evenly dispersed.

The Second Assistant gently slams the sealed, domed bag on a tabletop to close any open spaces, and increase the density of the mass. (In shaking, the mixture becomes quite loose.) The bag is positioned on a wire shelf where daily observations are made for the next few weeks. The bags are kept at least a finger breadth apart. These newly inoculated, incubating bags must not touch one another.

Now that the duties of the three laboratory personnel are clearly defined, working in concert becomes the foremost priority. A well-organized laboratory team achieves a furious pace. Conversation is kept to a minimum. (The person doing the inoculations can’t talk anyhow, except between sets of inoculations, lest his or her breath spreads bacteria. Wearing a filter mask reduces this risk.) However, times arise when one or more of the three-person production team is interrupted. During these down times, countertops should be vacuumed and wiped clean with alcohol. Garbage is consolidated. Finally one’s hands are washed prior to any more inoculation activity. The pace during the inoculation process should be both rhythmic and fast. Inoculations are purposely interrupted after every fifty or so bags so periodic cleaning can occur. Depending on the equipment, design of the facility, and experience of the laboratory personnel, better ways of organizing the labor during inoculations will naturally evolve. However, this method works well. Hundreds of bags can be inoculated during a single shift. Greater efficiency is realized if two or more sealers are employed simultaneously.

After inoculation, each bag can be shaken by hand. Larger farms place the bags onto a gravity conveyor leading to a multiple-bag, automatic shaking machine. As the crew’s performance improves with experience, block production soars into the thousands per shift. With each bag yielding US $10 to $50+, every doubling of production over a baseline level realizes proportionally greater profits for the owners.

Once shaken, the inoculated bags are placed on open wire shelves and spaced about 1 inch apart for incubation. Be forewarned that bags contacting one another are likely to contaminate with black pin or other thermophilic molds.

Incubation of the Production Blocks

The first 2 weeks of incubation after inoculation are the most critical. If the supplemented sawdust is not fully colonized during that time period, contamination usually arises soon thereafter. Within several days of inoculation, out-gassing of volatile by-products causes a distinctly noticeable fragrance. As soon as the laboratory is entered, the atmosphere imparts a unique “odor signature.” The smell is generally described as sweet, pleasant, and refreshing.

The laboratory should be maintained at 75°F (24°C) and have an ambient humidity between 30 and 50%. Since the internal temperatures of the incubating blocks are often 20°F higher than ambient air temperatures, keeping the laboratory warmer than recommended is likely to cause the internal incubation temperatures to rise to dangerous levels. Carbon dioxide levels within the laboratory should never exceed 1,000 ppm, although 20,000 to 40,000 ppm of CO₂ is typical within the bags as they incubate. This steep slope of high CO₂ within the bag to the low CO₂ in the atmosphere of the laboratory is helpful in controlling the evolution of metabolic processes. Should the gradient be less severe, CO₂ levels can easily exceed 50,000 ppm within the incubating bags. At this and higher levels, mycelial growth lessens and contaminants are encouraged. To compensate, adjust the laboratory air handling system for the proper mixing of fresh versus recirculated air. (See Appendix 2: Designing and Building a Spawn Laboratory.)

Three days after inoculation, the mycelium becomes clearly visible, often appearing as fuzzy spots of growth. Second shaking, although essential for insuring full colonization of grain spawn, is not usually advisable in the incubation of supplemented sawdust. If complete sterilization has not been achieved, second shaking can result in a contamination bloom. If one is certain that sterilization has been achieved, second shaking helps colonization, especially around days 4 and 5, but most cultivators find this extra step unnecessary.

Each species uniquely colonizes supplemented sawdust. Oyster mycelium is notoriously fast, as is Morel mycelium. “Good growth” can be generally described as fans of mycelium rapidly radiating outwards from the points of inoculation. Growth is noticeable on a daily, and in some cases, an hourly basis. When the mycelium loses its finger-like outer edges, forming circular dials, or distinct zones of demarcation, this is often a sign that contaminants have been encountered, although they may not yet be visible. The behavior of the mycelium constantly gives the spawn manager clues about the potential success of each run.

The cultivator should not operate under the belief that the supplemented sawdust blocks are absolutely free of contamination after autoclaving. In fact, they should be viewed as having a greatly reduced population of contaminants, which pose little problem as long as quick colonization by the mycelium occurs. Large runs of supplemented sawdust, however, are more likely to host minute pockets of unsterilized substrate than smaller runs would host. Should colonization be inhibited, or encouraged by any number of factors—poor strain vigor, a dilute inoculation rate, elevated internal thermal or carbon dioxide levels—contaminants are to be expected. This race between the mycelium and legions of competitors is a central theme operating throughout every stage of the cultivation process.

Achieving Full Colonization on Supplemented Sawdust

Prior to the mycelium densely colonizing the blocks with a thick and tenacious mycelial mat, the supplemented sawdust appears to be grown through with a fine, but not fully articulated, mycelial network. The once brown sawdust mixture takes on a grayish white appearance (with most species). With Shiitake mycelium, this is usually between days 3 and 7. During this state, the mycelium has yet to reach its peak penetration through the substrate. Although the substrate has been captured as a geological niche, the mycelial network continues to grow furiously, exponentially increasing in its micro-netting capacity. The bags feel warm to the touch and carbon dioxide evolution is great.

Within hours, a sudden transformation occurs: The once-gray appearance of the bags flush to snow-white. The fully articulated, thick mycelial network achieves a remarkable tenacity, holding fast onto the substrate. Now when each block is grasped, the substrate holds together without falling apart, feeling solid to the touch.

The blocks can be further incubated until needed, within certain time restraints. (Refer to Chapter 21 for the particular time requirements of each species.) With a one-room laboratory, inoculations and incubation can occur in the same space. If a multiroom laboratory is being used, then the supplemented sawdust blocks are furthest downstream from the precious petri dish cultures. In fact, they should be nearest the door for ease of removal. Ideally, this sequence of prioritizing cultures should follow each step in the exponential expansion of the mycelial mass:

• Petri dish cultures are furthest upstream, i.e., are given the highest priority.
• Grain spawn is organized in rank; downstream from the cultures maintained on malt agar media. First-generation, second-generation, and third-generation spawn are prioritized accordingly. Grain spawn, incubated in jars, is best stored at angles in vertical racks.
• Sawdust spawn, being created from grain spawn, is next in line. Second generation sawdust spawn is kept next downstream.
• Supplemented sawdust blocks designed for mushroom cropping, along with any other units destined for fruiting or implantation outdoors, are incubated closest to the exit.

As the mycelium is expanded with each generation of cultures, contamination is increasingly likely. This specified flow pattern prevents reverse contamination of upstream cultures from those downstream.

Once the mycelium achieves the above-described “grip” on the supplemented sawdust, the nature of the mycelium changes entirely. The blocks cease to generate heat, and carbon dioxide evolution abruptly declines. With most species, the blocks no longer need to be treated so delicately. They can be moved to secondary storage rooms, even thrown through the air from one person to another! (A new sport!?) This state of “mycelial fortitude” greatly facilitates the handling process. The blocks should be moved out of the laboratory environment and either taken to a staging room for later distribution to the growing room or a dark refrigeration room until needed. This resilient state persists until mushrooms form within the bags, either from the response of environmental change or not. Many strains of Lentinula edodes (Shiitake), Hericium erinaceus (Lion’s Mane), Grifola frondosa (Hen-of-the-Woods), Agrocybe aegerita (Black Poplar mushroom), and Pleurotus spp. produce volunteer crops of mushrooms within the bags as they incubate in the laboratory, without any environmental shift to stimulate them.

For many of the species listed in this book, volunteer fruitings begin 3 to 6 weeks after inoculation. Just prior to the formation of visible mushrooms, the topography of the mycelium changes. With Shiitake, “blistering” occurs. The smooth surface of the outer layers of mycelium roughens, forming miniature mountains and valleys. (See Chapter 21 for a complete description of this phenomenon.) With Lion’s Mane (Hericium erinaceus), dense, star-like zones form. These are the immediate precursors to true primordia. If these ripe bags are not taken to the growing room in time, the newly forming mushrooms soon malform: most frequently, with long stems and small caps. (These features are in response to high CO₂, lack of light, or both.) The young mushrooms at this stage are truly embryonic and must be treated with the utmost care. The slightest damage at this stage will be seen later—at the full maturity—as gross deformations: dimpled or incomplete caps, squirrelly stems, etc. Shiitake are particularly fragile at this stage whereas Oyster mushrooms can return to near-normal forms once exposed to the conducive climate of the growing room.

Handling the Bags Post-Full Colonization

Depending upon the species, 3 to 6 weeks pass before the bags are to be placed in the growing room. Before the blocks are moved in, the growing room has been aseptically cleaned, having been washed down with a bleach solution. After washing with bleach, I tightly close up the room for 24 hours and turn off all fans. The residual chlorine becomes a disinfecting gas permeating throughout the room, effectively killing flies and reducing mold contaminants. A day after chlorine treatment, fans are activated to displace any residual gas before filling. Additional measures prior to bleaching include replacing old air ducting with new, the changing of air filters, etc.

If you space the bags at least 4–5 inches apart, the developing mushrooms will mature without crowding. Sufficient air space around each block also limits mold growth. Galvanized stainless steel and/or epoxy-coated wire mesh shelves are preferred over solid shelves. Wood shelves should not be used because they will eventually, no matter how well treated, become sites for mold growth. Farms that do use wood trays either chemically treat them with an antifungal preservative to retard mold growth or construct them from redwood or cedar. I know of no studies determining the transference of toxins from chemically treated trays into mushroom fruitbodies. However, this concern is logically based, as mushroom mycelium absorbs some toxins, especially heavy metals.

Many wood decomposers can be grown on nonwood-based substrates such as cereal straws, cornstalks, sugarcane bagasse, coffee pulp, banana fronds, seed hulls, and a wide variety of other agricultural waste products. Since sources for hardwood by-products are becoming scarce due to deforestation, alternative substrates are in increasing demand by mushroom cultivators. However, not all wood decomposers adapt readily to these wood-free substrates. New mushroom strains that perform well on these types of alternative substrates are being selectively developed.

The more hearty and adaptive Pleurotus species are the best examples of mushrooms that have evolved on wood but readily produce on corncobs, cottonseed hulls, sugarcane bagasse, coffee waste, palm leaves, and cereal straws. When these materials are supplemented with a high nitrogen additive (rice bran, for instance), simple pasteurization inadequately treats the substrate, and sterilization is called for. (Without supplementation, pasteurization usually suffices.) Each cultivator must consider his or her unique circumstance juxtaposing the available substrate components, species, facilities, and market niches—in their overall system design.

Growing the Oyster Mushroom, Pleurotus ostreatus, on straw is less expensive than growing on sterilized sawdust. In contrast, Shiitake, Lentinula edodes, which barely produces on wheat straw is best grown on wood-based substrates.¹ When both straw and sawdust are difficult to acquire, alternative substrates are called for. Mini-trials are encouraged before substantial resources are dedicated to any commercial enterprise. I encourage readers to formulate new blends of components that could lead to a breakthrough in gourmet and medicinal mushroom cultivation.

Coffee grounds, if they are inoculated soon after expressing, are a ready-made substrate for Oyster mushrooms, Pleurotus ostreatus and Pleurotus pulmonarius, and for Reishi, Ganoderma lucidum.

Alternative Fruiting Formulas

Here is a basic formula, not using wood or straw, for the cultivation of wood-decomposing mushrooms. A nitrogen supplement, in this case, rice bran, is added to boost yields. As discussed, the substrate must be heat-treated by any one of a number of methods to effect sufficient sterilization.

The amount of calcium carbonate can be altered to effectively raise pH, offsetting any inherent acidity. The components are mixed in dry form and wetted until a 70–75% moisture content is achieved. The mixture is loaded into bags and immediately heat-treated. Should the bags sit overnight, and not be autoclaved, contaminants proliferate, making the mixture unsuitable for mushroom cultivation.

The methods described here for the cultivation of mushrooms indoors on straw can be extrapolated for cultivating mushrooms on chopped cornstalks, sugarcane bagasse, and many other agricultural waste products. In contrast to wood wastes, which should be sterilized, I believe most agricultural by-products are better pasteurized using steam or hot water baths. Pasteurization selectively kills the majority of competitors, preserving populations of noncompetitive thermotolerant fungi, resulting in a substrate with a limited window of opportunity for contamination, and in turn, favors the dominance of mushroom mycelium. Pasteurization typically occurs between 140 and 180°F (60 and 82°C) at atmospheric pressure (1 psi). Sterilization is by definition above the boiling point of water, >212°F (100°C), and above atmospheric pressure, i.e., >1 psi. A hybrid treatment, which I call atmospheric sterilization or “super-pasteurization” calls for the exposure of substrates to prolonged, elevated temperatures exceeding 190°F (88°C) for at least 12 hours. In any case, a carefully balanced aerobic environment must prevail throughout the incubation process or competitors will flourish.

Readily available, inexpensive, and needing only a quick run through a shredder (and sometimes not even this), wheat straw is ideal for both the home cultivator and commercial cultivator. Straw is a “forgiving” substrate for the small to midsized cultivator, accepting a limited number of contaminants and selectively favoring mushroom mycelium. Growing on straw is far less expensive than growing on sawdust. Many cottage growers enter the gourmet mushroom industry by first cultivating Oyster mushrooms on straw. Wheat, rye, rice, oat, and sorghum straws are the best. Hay, resplendent with abundant bunches of seed kernels, should not be used as the grain kernels tend to contaminate. However, limited numbers of grain kernels generally boost yields. Royse (1988) found that yields of Oyster mushrooms from wheat straw are enhanced by the addition of 20% alfalfa without increasing the risk of contamination. Alfalfa, by itself, is “too hot” to use because of its elevated nitrogen content. Straw supports all the gourmet Oyster mushrooms, including Pleurotus citrinopileatus, P. cystidiosus, P. djamor, P. eryngii, P. euosmus, P. ostreatus, P. pulmonarius, and Pleurotus tuberregium. Other mushrooms, King Stropharia (Stropharia rugosoannulata), Shaggy Manes (Coprinus comatus), the Paddy Straw (Volvariella volvacea), and Button (Agaricus spp.) mushrooms also thrive on straw-based substrates, often benefiting from modest supplementation.

Coffee waste in Mexico and Central America has become a major ecological catastrophe, polluting rivers and aquifers. Coffee pulp is an ideal substrate for growing Oyster mushrooms. Not only have yields in excess of 159% biological efficiency been reported, but residual material, post-harvesting, has largely been denatured of caffeine and is suitable as feed for many farm animals (Martinez-Carrera, 1987, 1988; Leon-Chocoo, 1988; Thielke, 1989). Coffee plantations and Oyster mushroom farms are complimentary industries. This is yet another example that mushroom cultivation is the missing link in the integration of complex systems of human enterprises within a sustainable environment.

The specifics for cultivation of each of these species are discussed further on, in Chapter 21.

A simple and easy method for pasteurizing straw (and other bulk materials). The drum is filled with water and heated with the propane burner at 160°F (71°C) for 1 to 2 hours.

Shredding and moistening straw.

Heat-Treating the Bulk Substrate

Bulk substrates like straw are generally pasteurized (as opposed to sterilized) and upon cooling, inoculated with grain spawn. Pasteurization selectively kills off populations of temperature-sensitive microorganisms. The population left intact presents little competition to the mushroom mycelium for approximately 2 weeks, giving ample opportunity for the mushroom mycelium to colonize. If not colonized within 2 weeks, the straw naturally contaminates with other fungi, irrespective of the degree of pasteurization. Straw is first chopped into 1-inch to 4-inch lengths and can be prepared via several methods.

Monitoring water temperature.

Straw is stuffed into a wire basket and then placed into the hot water. A weight is placed to keep the straw submerged.

The Hot Water Bath Method: Submerged Pasteurization

The first method is the hot water bath. Straw is stuffed into a wire basket and submerged in a cauldron of 150–180°F (65–82°C) water for 1 hour.² The soaking cauldron is usually heated from underneath by a portable propane gas burner. The straw basket is forcibly pushed down into the steaming water and held in place by whatever means necessary. A probe thermometer, at least 12 inches in length, is inserted deep into the mass, with string attached for convenient retrieval. When water temperature reaches 160°F, the straw is submerged for at least 1 hour and no longer than 2.

Upon removal, the straw is well drained and laid out in a shallow layer onto cleaned surfaces (such as a countertop) to rapidly cool. Most cultivators broadcast grain spawn over the straw by hand. Gloves should be worn but often are not, and yet success is the norm. In either case, the hands are thoroughly and periodically washed, every 15 minutes, to limit cross-contamination. The spawn and straw are then mixed thoroughly together and placed directly into trays, columns, wire racks, or similarly suitable containers.

Another basket of chopped straw can be immersed into the still hot water from the previous batch. However, after two soakings, the hot water must be discarded. The discolored water, often referred to as “straw tea,” becomes toxic to the mushroom mycelium upon the third soaking, retarding or preventing further mycelial growth. Therefore, the water must be changed after the second soak. (Interestingly, this tea is toxic to most vegetation and could be used as a natural herbicide.)

A brick keeps the straw submerged during pasteurization.

After 1 to 2 hours of submerged pasteurization, the basket is lifted out. After draining excess water, the straw is cooled, and grain or sawdust spawn is broadcast over the surface and mixed throughout the straw.

The “Phase II” Chamber: Steam Pasteurization

A second method calls for the placement of straw in a highly-insulated room into which steam is injected. This room is known as the Phase II chamber. Before the straw is loaded into the Phase II chamber, it must be moistened. This can be done simply by spreading the chopped straw over a large surface area, a cement slab or plastic tarpaulin to a depth no greater than 12 inches. Water is sprayed on the straw via sprinklers over a 2- to 4-day period. The straw is turned every day to expose dry zones to the sprinkling water. After several turns, the straw becomes homogeneous in its water content, approaching 75% moisture, and is reduced to about half its original volume. Once evenly moistened, the straw is now ready for loading into the steam chamber. Short-stacking the straw is not intended to accomplish composting, but rather a way of tendering the straw fiber, especially the waxy, outer cuticle. In contrast to composting, the straw is not allowed to self-heat.

An alternative method calls for the construction of a large vat into which straw is dunked. This tank is usually fitted with high-pressure water jets and rotating mixing blades to assure full moisture penetration into the straw. If given sufficient agitation, finely chopped straw gains 75% moisture in the matter of minutes. Once moistened, the straw is loaded directly into the Phase II chamber.

One ton of wheat straw, chopped and soaked, occupies approximately 250 cubic feet of space, equivalent to 10 × 10 × 2.5 feet. This figure is helpful in sizing a pasteurization chamber. An additional 25% allowance should be made for variation in the chop size of straw, air plenums, and handling needs. Five dry tons of wheat straw functionally fills a 1,000-square-foot growing room. Most growers fill growing rooms to no more than one-fourth of total air volume. I prefer to fill to only one-eighth of capacity. This means that for every eight air spaces, one space is occupied by substrate. (In other words, the ratio of air-to-substrate space is 7:1.)

The classic Phase II room has a raised, false floor, screened several inches above the true floor upon which a latticework of steam pipes, are situated. The walls and ceiling are well insulated. The interior panels are made of heat-resistant, waterproof materials. Many convert shipping containers used to ferry cargo on ships into Phase II chambers. Others custom-build their own steam rooms.

Another important feature is a floor drain fitted with a gate valve. This valve prevents contamination from being drawn in during and after pasteurization.

Boilers provide live steam, dispersed through the pipes, and into the straw, which can be filled to a depth as great as 8 feet. The greater the depth, the longer heat takes to penetrate to the center. Heat penetration can be enhanced with high-pressure blowers. At least three remote reading temperature probes are inserted at various locations: low (within 4–6 inches), midway, and high (within 12–24 inches of the top surface). These temperature probes should be monitored periodically to gather data for the generation of a pasteurization profile specific to each run. Over time, the temperature points of each successful batch are accumulated for establishing a baseline for future operations.

Profile of an automated bulk processing for soaking and pasteurizing straw. After pasteurization, the steamed mass is pulled via a netted floor into two outwardly rotating teethed cylinders that throw the straw onto conveyors. In this case columns are filled, although trays or other fruiting vessels could just as well be used.

When steam is injected, the outer edges of the straw mass heat up first. An outer zone of high temperature forms, and over time increasingly enlarges towards the center. Early on in the Phase II process, three thermometers can read a range from room temperature to 160°F (71°C) simultaneously. This temperature differential must be monitored carefully. The core of a densely packed Phase II steam chamber remains below 100°F (38°C) for several hours, lagging behind the hot outer shell, and then suddenly races upwards. If steam output from the boilers is not reduced in time, the entire mass continues to heat at an uncontrollable rate. Without the cold core, which in effect is a heat-sink, to deflect the spiraling increase in temperature, thermal momentum continues for an hour or two beyond the time steam injection is shut off. The entire mass must not exceed 200°F (93°C) The minimum recommended time for pasteurization is 2 hours above 160°F (71°C).

A common oversight in steaming a mass of straw or compost is the failure to chart, every 30 minutes, the temperature profile of the mass. With measuring and charting, trend analysis is possible. If the climb in temperature is not anticipated or reduced at the right time, the thermal momentum of the hot outer shell not only overwhelms the ever-shrinking cold core, but cause the entire mass to skyrocket to 200+°F (93°C), a temperature above which disaster awaits. Above this temperature plateau, noncompetitive, beneficial organisms are killed, and the substrate becomes an open habitat for many competitors that would otherwise be held in abeyance.

Screened floor racks allow the passage of steam underneath the bulk material being pasteurized.

Inside a large Phase II designed for growing Button mushrooms.

When the steam output from the boiler is turned off, the Phase II box should be immediately positive-pressurized with contaminant-free air. By forcing air through a HEPA filter and ducting the air directly into the Phase II chamber, you prevent contaminants from being sucked in as the mass cools. For a steam box measuring 10 cubic feet, a ⅛-HP (horsepower) blower pushing 200 CFM (cubic feet per minute) through a 12 × 12 × 6-inch HEPA filter (99.99% @ .3 µ) adequately positive-pressurizes the chamber. (Larger Phase II rooms will require correspondingly higher pressure fans able to push air over 2–4 inches of static pressure.) The substrate mass slowly cools in 12 to 24 hours to temperatures tolerable for inoculation, generally below 105°F (38°C).

Before the pasteurization chamber is opened, the inoculation area is intensively clean with a 10% bleach solution.³ To aid the cleaning process, venturi siphon mixers are ideal for drawing bleach directly into a hose line at the faucet connection. Conveyor belts, countertops, funnels, ceilings, and walls are all cleansed with torrents of chlorinated water. Spraying down the room with such a solution is colloquially termed “bleach bombing” in the industry. Protective clothing is advised for the sanitation personnel.

Temperature profile of a Phase II run.

Methods vary for the unloading of the Phase II chamber. Some remove the straw by hand with clean pitchforks and throw the straw onto stainless steel tables whereupon the inoculation occurs. Conveyors are favored for substrate handling by many growers. The largest Phase II chambers utilize a netted or “walking” floor, which pulls the substrate mass into two outwardly rotating, horizontally positioned, teethed cylinders. (See illustration.) As the substrate mass is forced into the space between the two outwardly rotating, spiked cylinders, the straw is separated and ejected onto a depressed platform in whose center is a funnel or ramp that leads to conveyors. (Warning: The danger of personal injury here at this juncture is notorious. Special precautions must be implemented to prevent accidents.) After the straw is thrown into the conveyor belt, grain spawn is automatically fed or hand-broadcast onto the straw as it is being ferried away. Foot-activated switches are helpful in controlling the off-loading of the substrate from the Phase II box with the conveyor.

When spawn is placed directly upon the surface of pasteurized straw, mixing is strongly advised. Cement and soil mixers, specially adapted funnels, ribbon blenders, and “Archimedes screws” suffice. If the spawn is laid upon straw and not mixed through, growth layers form resulting in uneven colonization. The advantage of removing the straw and inoculating by hand is that the process can be interrupted and recurrent cleaning can occur. With intermittent disinfecting, cross-contamination can be prevented. With automated, continuous-loop systems, the likelihood that contamination can travel throughout the facility unchecked is greater. Special attention to detailed disinfection is necessary with these systems to prevent disastrous results should pasteurization be incomplete. Once spawn has been sown throughout the straw, the inoculated substrate is placed directly into the “fruiting” containers, usually columns, trays, or bags. Each container must be vented so the mycelium can respire as it colonizes the substrate.

Alternative Methods for Rendering Straw and Other Bulk Substrates for Mushroom Cultivation

Several inexpensive, alternative methods can be used for treating straw (and other bulk materials) that do not involve heat-treatment. The first three are chemical; the last is biological. Surely other alternative methods will be developed as imaginative entrepreneurs experiment. By sequencing a substrate through a combination of biological and chemical treatments, you can avoid heat pasteurization entirely. Small pilot-scale experimentation is strongly encouraged before cultivators attempt these techniques commercially. The future use of such methods appears extremely promising.

The Hydrated Lime Bath Method

Hydrated lime (calcium hydroxide) is extremely alkaline and water-soluble. By immersing straw into water baths high in hydrated lime, competitor fungi and bacteria are largely rendered inactive from the drastic change in pH. The preparation is quite simple.

Two to four pounds of lime is added for every 50 gallons of water. (Since a gallon of water weighs 8.3 pounds this ratio is equivalent to 2–4 pounds lime/415 pounds water or about .5–1.0%.) The pH of the water skyrockets to 9.5 or higher. Once dissolved, chopped straw is immersed into this highly alkaline bath. Under these caustic conditions, pH-sensitive microorganisms soon die. Subsequent to an overnight soaking, the water is drained and discarded. (Note that this highly alkaline water kills many plants and should be prevented from entering any watershed.) The straw is then drained and inoculated using standard methods. It is not unusual for the straw to achieve a pH of 8.5 or higher after soaking. Oyster mushroom mycelia can tolerate this alkaline environment better than most competitors. After 3 or 4 days of initial growth, pH slowly falls as the mycelium races through the straw, secreting acids and enzymes. One week after inoculation, the straw should be fully colonized. If colonization is not complete within 7 to 10 days, competitors usually arise. Optimizing the parameters for the species being cultivated greatly influences the success or failure of this simple method. Please consider that the starting pH of makeup water affects the final outcome. Each cultivator must compensate accordingly.

The Bleach Bath Method

This is similar to the hydrated lime bath method, but household bleach (5.25% sodium hypochlorite) is used as a disinfectant. I recommend adding 3–4 cups of household bleach to 50 gallons of water. A basketful of chopped wheat straw is immersed. The straw is kept submerged for a minimum of 4 and no more than 12 hours. The bleach leachate is drained off. The straw is immediately inoculated with an aggressive species such as Pleurotus pulmonarius. Should colonization not be complete within a week, contaminants naturally occur. Cultivators should be careful where the toxic leachate is drained. Gloves should be worn to protect the skin from chemical burning.

The Hydrogen Peroxide Technique

Hydrogen peroxide has been a traditional method for disinfection for more than a century. Recently, this method was, in a sense, rediscovered by chemist Rush Wayne, who, having become frustrated with the difficulty and expense of creating a sterile environment in his home, refined this technique to a practical level. He has published a booklet on this technique (Wayne, 1999). The usefulness of this technique on a commercial scale has yet to be proven but this method is well worth a careful economic study. Its main advantage is that it offers an alternative method to those who do not have access to many of the more expensive tools-of-the-trade. The readers should note, however, that much resident contamination can survive this process, and it is not as effective as many other methods. Nevertheless, Rush Wayne has provided an excellent service by continually refining this technique.

Hydrogen peroxide (H₂O₂) works to kill many fungal spores, yeasts, and bacteria by producing a reactive form of oxygen, which destroys cell walls. However, because fungal mycelium has evolved to decompose organic compounds in the environment using peroxides, the mushroom mycelium and the mycelia of contaminant molds are protected from its oxidizing effects. If colonies of mycelium from contaminant fungi have already developed, this method will be of limited advantage. However, most contaminant spores will be neutralized when in contact with peroxide. The advantage of hydrogen peroxide is that it topically destroys resident spores within many of the substrates useful for cultivation, especially those present in dry form, or in the media. It also provides some protection from airborne vectors when the media is exposed. However, since hydrogen peroxide is so reactive, it does not provide much protection from airborne contamination after absorption by the host substrate.

Although not thorough enough to neutralize most of the natural fungal contaminants resident in raw sawdust, straw, or composts, hydrogen peroxide can help complete the process started with many preheated substrates. When wood is baked in an oven at 300°F (149°C) for 3 hours, compounds are destroyed in the wood that would otherwise neutralize the peroxide. This technique is an effective heat pretreatment. Or, the heat-treated, hardwood fuel pellets used for wood stoves can first be boiled in water, drained, and then allowed to cool. Hydrogen peroxide can be diluted 100-fold, from 3% to .03%, into water (less than 140°F or 60°C). This water can then drench the substrate to further reduce the likelihood of competitors. When diluted hydrogen peroxide is added to wood and allowed to sit for 8 hours, the substrate can then be inoculated with a modicum of success. However, this technique is good for only one generation of transfers at most, which means one unit of pure culture spawn can inoculate five to twenty units of peroxide-treated sawdust, but these units cannot easily be used for further expansion without likelihood of a major contamination bloom. This limitation means that this technique is more applicable to home cultivators than to commercial cultivators.

This is but one of many examples. Any technique that leaves a window of opportunity open long enough for the mushroom mycelium to dominate, generally 7 to 10 days, is worth pursuing.

The High-Pressure Extrusion Method

Another pass-through method for treating straw and sawdust utilizes the heat generated from the extrusion of a substrate from a large orifice through a smaller one. This methodology was first developed for the commercial feed industry in the creation of pelletized rabbit, chicken, and cattle feed. The effective reduction of the substrate causes frictional heat to escalate. For instance a 6:1 reduction of straw into a 10-millimeter-sized pellet creates a thermal impaction zone where temperatures exceed 176°F (80°C), temperatures sufficient for pasteurization. Large commercial units can process up to 2,000 pounds per hour. (One supplier has a home page at www.amandus-kahl-group.de.) Pellets between 50 and 100 millimeters in diameter are better suited for fruitbody production than the smaller pellets. However, the smaller pellets might be more useful as spawn in the outdoor introduction of mycorrhizae or for the introduction of mycelia for purposes of mycoremediation of toxic habitats. Another technology being tested uses a roller mechanism rather than a narrow orifice, and can process much more substrate mass.

The Detergent Bath Method

This method simply utilizes biodegradable detergents containing fatty oils to treat bulk substrates. Coupled with surfactants that allow thorough penetration, these detergents kill a majority of the contaminants competitive to mushroom mycelium. The substrate is submerged into and washed with a detergent solution. The environmentally benign wastewater is discarded, leaving the substrate ready for inoculation. Recently, many environmentally safe soaps have been developed, especially in Europe. Cultivators are encouraged to experiment to match the best detergents to their substrate materials. Here again, the goal is to create a process that is both simple and applicable for small- and large-scale cultivators.

The Yeast Fermentation Method

Another alternative method for rendering straw is biological. Straw can be biologically treated using yeast cultures, specifically strains of beer yeast, Saccharomyces cerevisiae. This method, by itself, is not as effective as those previously described one but has achieved limited success. Research into the sequencing of multiple microorganisms may improve success.

First a strain of beer yeast is propagated in 50 gallons (200 liters) warm water to which malt sugar has also been added. Recommended rates vary. Usually a 1–5% sugar broth is concocted. Fermentation proceeds for 2 to 3 days undisturbed in a sealed drum at room temperature (75°F, 24°C). Another yeast culture can be introduced for secondary, booster fermentation that lasts for another 24 hours. After this period of fermentation, chopped straw is then forcibly submerged into the yeast broth for no more than 48 hours. Not only do these yeasts multiply, absorbing readily available nutrients, which can then be consumed by the mushroom mycelium, but metabolites such as alcohol and antibacterial by-products are generated in the process, killing competitors. Upon draining, the straw is inoculated using standard procedures.

Another method of submerged fermentation uses the natural resident microflora from the bulk substrate. After 3 to 4 days of room-temperature fermentation, a microbial soup of great biological complexity evolves. The broth is now discarded and the substrate is inoculated. Although highly odoriferous for the first 2 days, the offensive smell soon disappears and is replaced by the sweet fragrance of actively growing mycelium. I hesitate to recommend it over the other procedures described here.

The outcome of any one of these methods greatly depends on the cleanliness of the substrate being used, the water quality, the spawn rate, and the aerobic state of the medium during colonization. These methods generally do not result in the high consistency of success (>95%) typical with heat treatment techniques. However, with refinement, these simple and cheap alternatives may prove practical wherever steam is unavailable.

Choosing the “best” type of cropping container depends upon a number of variables: the mushroom species, the cultivator, and the equipment/facility at hand. White Button growers typically grow in trays, made of either wood or metal. Facilities designed for growing Button mushrooms (Agaricus species) encounter many difficulties in their attempts to adapt to the cultivation of the so-called exotic mushrooms. For instance, most Oyster mushrooms have evolved on the vertical surfaces of trees, and readily form eccentrically attached stems. Because Oyster mushrooms require healthy exposure to light, the darkened, dense-packed tray system gives rise to unnatural-looking, trumpet-shaped Oyster mushrooms. This is not to say that Oyster strains cannot be grown en masse in trays. However, many Oyster strains perform better, in my opinion, in columns, vertical racks, or bags. After taking into account all the variables, cultivators must decide for themselves the best marriage between the species and the cropping container. Please consult Chapter 21 for specific recommendations for the cultivation of each species.

Wooden tray cultures of the Button mushroom (Agaricus brunnescens) at a commercial mushroom farm.

Tray Culture

Growing mushrooms in trays is the traditional method of cultivation, first developed by the Button mushroom (Agaricus) industry. Trays range in size from small 2 feet × 3 feet × 6 inches deep, which can be handled by one person to trays 6 feet × 10 feet × 12 inches deep, which are usually moved into place by electric or propane-powered forklifts. For years, trays have been constructed of treated or rot-resistant wood. More recently, polycarbonate and aluminum trays have been introduced with obvious advantages. Both types are designed to stack upon each other without additional structural supports.

Trays allow for the dense filling of growing rooms (up to 25% of the volume) and because Agaricus brunnescens, the Button mushroom, is not photosensitive, no provisions are made for the equal illumination of the beds’ surfaces. The main advantage of tray culture is in the handling of substrate mass-filling, transporting, and dumping. The Dutch are currently using tray culture for the cultivation of Button, Shiitake, Oyster, and other mushroom species.

Tray culture easily accepts a casing layer. Casing layers are usually composed of peat moss and vermiculite, and buffered with calcium carbonate and applied directly to the surface of a myceliated substrate. Button mushroom production excels from the application of a casing layer whereas it is debatable whether yields from the wood decomposers are substantially affected.¹ Those using trays and not applying a casing must take extra precaution to ensure the necessary microclimate for primordia formation. This can be accomplished by covering the trays with either a perforated layer of plastic or breathable, anti-condensate films. The plastic is stripped off, depending upon the species, at the time of, or soon after, primordia formation. High-humidity, but less than fog-like, environments typically ensue until the primordia have firmly set. The transpiration of water, “wicking of moisture,” is an active process benefiting the raising of nutrients to the primordia sites.

In North America, Davel Brooke-Webster (1987) first perfected tray culture for Oyster mushrooms. (See examples here.) This method utilizes a perforated plastic covering over the surface of trays. Since many Button mushroom farms are centered on tray technology, the replacement of the casing layer with a sheet of perforated plastic allows the cultivation of both species at the same facility. Holes (1- to 2-inches in diameter) are punched evenly through an 8-foot roll of plastic, before application. The plastic sheeting is stretched over the trays, directly after inoculation of Oyster spawn into pasteurized wheat straw. The plastic barrier prevents 98% of the evaporation that would otherwise occur had the inoculated straw remained exposed. Even with the plastic covering, humidity within the growing room should remain relatively high so that the straw exposed to the air directly below the holes does not “pan” or die back. A sure sign that the growing room humidity is too low is when brown zones of dry straw form around each puncture site while the remainder of the substrate is white with mycelium.

An advantage of the Brooke-Webster technique is bouquets of equal weight produced simultaneously on the same horizontal trays so widely used by the Button mushroom (Agaricus brunnescens) industry. This adaptation has been put into practice by Himematsutake (Agaricus blazei) growers. A disadvantage of tray culture is that equal exposure of light over the surface of each tray, when tightly stacked upon one another, is difficult. (When providing light to tightly packed trays, cultivators usually mount the fixtures on the underside of the tray immediately above the fruiting surface. Most cultivators remove the heat-generating ballast to a remote location and recapture the heat into their air circulation system.) Another method is to line the bottom of wire mesh trays with perforated white plastic. Lights can be mounted vertically on the walls of the growing room. The white undersides of the trays help disperse light across the tops of the beds. When lighting is insufficient in Oyster mushroom cultivation, stems elongate while caps remain underdeveloped, causing abnormal, fluted, or trumpet-shaped mushrooms.

The key to the success of this method lies with strains that form bouquets of mushrooms site-specifically at the holes in the plastic. Ideally, primordial clusters hosting multiple mushrooms form at each locus. (See Chapter 14: Evaluating a Mushroom Strain.)

The author in front of aluminum trays filled via the Dutch pulled-net system.

Horizontal trays covered with perforated plastic allow for the simultaneous emergence of Oyster mushroom bouquets from pasteurized wheat straw. (In this case the variety being cultivated is the “sajor-caju” variety of Pleurotus pulmonarius. This technique can be adapted for encouraging large Portobellos (Agaricus brunnescens) and Himematsutakes (Agaricus blazei).

The Phoenix Oyster, Pleurotus pulmonarius fruiting from a wall formation of stacked bags.

Vertical Wall Culture

In the evolution of techniques, the Agaricus tray has been modified for growing Oyster mushrooms by turning it vertically so mushrooms could fruit out both faces. Usually these vertical surfaces are screened with tight wire or plastic mesh. Perforated plastic positioned between the substrate and the wire mesh allows the formation and development of mushrooms while retaining moisture. Alternately, a plastic curtain is used to envelope the container until the time of fruiting.

Racks having a breadth of 12–16 inches support full flushes and generally do not become anaerobic near the core, a problem seen when racks are 20 inches and more in breadth. If properly designed, individual 4 × 4-foot to 4 × 8-foot rack frames can be stacked upon each other in the construction of continuous mushroom walls. With one side of the frame hinged for opening, filling is made easy.

Another variation of wall culture is the building of walls by stacking polypropylene bags, sideways, on top of one another. Only the ends of the bags have an opening, causing mushrooms to form on the exposed outer surface of the constructed wall. Here, forming the bags into a square shape during incubation facilitates wall construction. Some cultivators hang walls of substrate from roof trusses.

Slanted Wall or A-Frame Culture

Slanted walls are constructed by stacking bags of inoculated substrate to build sloped faces. The advantage of the slanted wall is that a higher density of fill can be achieved within a given growing room space and harvesting is easier. The disadvantage is that mushrooms are limited to forming on only one plane—the outwardly exposed surface. In comparison, blocks that are spaced apart give rise to fruitings on five planes: the four sides and the top, a response seen especially with Shiitake and Oyster mushrooms.

Many cultivators find that a wall composed of individually wrapped blocks limits cross-contamination from infected units. Isolation of the blocks, or for that matter any fruiting container, has distinct advantages, both in terms of yield enhancement and contamination containment.

Black Reishi, Ganoderma lucidum, fruiting from wall formation of stacked bags.

Bag Culture

In the search for inexpensive, portable, and disposable containers, plastic bags have became the logical choice. High-temperature-tolerant polypropylene bags are primarily used for processing wood-based substrates, which require higher temperature treatment than the cereal straws. Once cooled and inoculated, sterilized substrates are usually filled, directly into heat-sensitive polyethylene bags. Mushrooms fruit from the top or sides.

For the cultivation of most wood decomposers, a biodegradable, heat-tolerant, and breathable plastic for bag culture is sorely needed. “Cellophane,” a wood cellulose-based plastic-like material used commonly in the mid-1900s, has some of these features (heat tolerance, gas porosity), but lacks durability. Despite this shortfall, one of the most appealing aspects of cellophane is that mushroom mycelium digests it in the course of its use. With mushrooms having such great potential for recycling wastes, it is ironic that plastics so fulfill a critical need among cultivators. Some ingenious restructuring of cellulose could satisfy this increasing market for environmentally sensitive cultivators. This technology would be highly patentable and serve a wide variety of industries—from mushroom centers to medical laboratories.

Bag culture first became popular for the Button mushroom industry and is still used to this day. Inoculated compost is filled into the bags topped with a soil-like casing layer. Individual bags are grouped on horizontal shelves. By preventing contact between the mycelium and the wooden shelves, contamination, especially from the wood-loving Trichoderma and Botrytis molds, is minimized.

A white Oyster mushroom, Pleurotus ostreatus, fruiting from custom made plastic grid-frame.

The hinged wall-frame—two trays latched together in the center. Mushrooms fruit out both sides. (Frame has been turned 90 degrees on side for photograph.)

Slanted wall culture of Shiitake, constructed of stacked sawdust blocks.

Primordial cluster of Oyster mushroom emerging through hole in plastic.

Oyster mushrooms fruiting from suspended bags. Elongation of stems is due to elevated CO₂ levels.

Many growers favor plastic bags for their ease of use. When holes are punched through the plastic, mushrooms emerge soon thereafter. Opaque, black bags encourage photosensitive strains of mushrooms to form only where the holes allow light exposure. Clear bags stimulate maximum populations of mushroom primordia but often, primordia form all over. Cultivators must remove the appressing plastic or selectively release colonies of primordia with sharp blades to insure crop maturity. However, many cultivators overcome this problem by using select Oyster strains that localize primordial clusters at exactly the puncture sites. By punching dozens of holes with stainless steel, four-bladed arrowheads, large bouquets of mushrooms are encouraged to form at the hole sites. From the force of the enlarging mushrooms, the flaps are pushed opened. This method has many advantages and is highly recommended.

Bag culture of the Button mushroom (Agaricus brunnescens).

Bouquets of Golden Oyster mushrooms (Pleurotus citrinopileatus) fruiting from columns of pasteurized wheat straw within a growing room.

Bag culture of the Oyster mushroom (Pleurotus ostreatus).

Column Culture

Growing Oyster mushrooms in columns gives rise to natural-looking fruitbodies. Having evolved on the vertical surfaces of hardwood trees, Oyster mushrooms, with their off-centered stems, grow out horizontally at first, turn, and grow upright at maturity.² This often results in the formation of highly desirable clusters, or “bouquets,” of Oyster mushrooms. The advantage of cropping clusters from columns is that many young mushrooms form from a common site, allowing ¼- to 1-pound clusters to be picked with no further need for trimming. Yields of succulent young mushrooms are maximized while spore load is minimized; harvesting is far faster than picking mushrooms individually; clusters store far better under refrigeration than individual mushrooms.

Cross-section of 15-inch-diameter column of Oyster mushroom mycelium contaminated with an anaerobic core.

Inoculating columns. First plastic ducting is cut to length and secured to the stainless steel funnel. (I had a spring-activated collar custom-made for this purpose.) A knot is tied several inches off the ground.

Automated column-packing machines have been developed and tested in North America and Europe with varied results. Typically the machines rely on an auger or “Archimedes screw,” which forces the straw through a cylinder with considerable force. Straw can be pasteurized, cooled, and inoculated along a single production line. Columns are packed, usually horizontally, in a sleeve that can be removed for the vertical placement of the column in the growing room. Several inventive engineers-turned-mushroom-growers are currently developing production systems based on this concept. For many, separating each activity—pasteurization, inoculation, filling, and positioning—simplifies the process.

Vertical cylinders can be made of a variety of materials. The least expensive is the flexible polyethylene ducting designed for air distribution in greenhouses, available in rolls as long as 5,000 feet and in diameters from 6–24 inches.³ Drain-field pipe, polycarbonate columns, and similar “hard” column materials have also been employed with varying degrees of success. The more extravagant systems utilize inner rotating, perforated, hard columns equipped with centrally located air or water capillaries that double as support frames, but I have yet to see such a system perfected. Many farms even use overhead trolleys for ferrying the columns into and out of the growing rooms. (See illistration.) Of the many variations of column culture, the ease and inexpensiveness of the flexible polyethylene tubing has yet to be surpassed.

As the substrate fills the column, spawn is added and the plastic elongates.

When the column is slammed to the floor during filling, the straw packs densely.

Once filled, the collar is released and the plastic is tied into a knot.

Some growers strip the columns after colonization to expose the greatest surface area. The columns are held together with two to four vertically running lengths of twine. Although the intention is to maximize yield, the massive loss of moisture, combined with the dieback of exposed mycelium, can cancel any advantage contemplated. El-Kattan (1991) and others who have conducted extensive studies have found the accumulation of carbon dioxide during colonization has an enhancing effect on subsequent yields. Studies prove the partially perforated plastic gives rise to larger fruitings of Oyster mushrooms sooner than substrates fully exposed. Exposed columns not only lose more moisture, but they also allow the sudden escape of carbon dioxide, resulting in a substantial reduction of the total mass of the substrate. Zadrazil (1976) showed that fully 50% of the mass of wheat straw evolves into gaseous carbon dioxide during the course of Oyster mushroom production! (See Byproducts of Straw Substrate Due to Conversion by Pleurotus ostreatus chart.)

Another factor in choosing the type of column culture is greatly determined by the mushroom strain. Strains of Oyster mushrooms, which produce clusters of many mushrooms and which are site-specific to the perforations, work better in the perforated column model than in the fully exposed one. Mushroom strains that produce only one, two, or three mushrooms per cluster—as with some Pleurotus pulmonarius cultures—do not demonstrate an obvious advantage with the perforated column culture method. Hence, the benefits of perforated column culture can be easily overlooked unless you test many Oyster mushroom strains.

From extensive trials, I have determined functional limits in the cultivation of Oyster mushrooms in columns. Columns less than 8 inches give meager fruitings and dry out quickly. Columns whose diameters exceed 14 inches are in danger of becoming anaerobic at the core. Anaerobic cores create sites of contamination, which emanate outwards, often overwhelming the outer layer of mycelium.

Columns are best filled with bulk, pasteurized substrates (such as straw) via conveyors leading to a stainless steel funnel. If conveyors are unavailable, then the pasteurized straw can be moved from the steam room (Phase II box) to a smooth-surface tabletop via a pitchfork. Either on the conveyor or on the tabletop, grain spawn is evenly distributed. The inoculated substrate is then directed to the recessed funnel. The funnel should be positioned 10–14 feet above the floor. Plastic ducting is precut into 12-foot lengths and tied into a tight knot at one end. The open end of the plastic tube is pulled over the cylindrical downspout of the funnel and secured via bungee cords or, preferably, a spring-activated, locking collar.

Since the tensile strength of a 12-inch-diameter, 4-millimeter-thick, polyethylene tube is insufficient to suspend the mass of moist straw tightly packed into an 8-foot-long column, care must be taken in filling. After securing the empty plastic column 4–6 inches above the floor, the plastic column slowly elongates with substrate filling. When a few air-release holes are punched near the bottom of the column, air escapes during filling, facilitating loading. Most importantly, cavities—air pockets—must be eliminated. As the column is filled, the poly tubing stretches until partially supported by the floor. As the column fills with substrate, a worker hugs the column, gently lifts it several inches off the floor, and forcibly slams it downwards. The impact against the floor increases substrate density and eliminates cavities. This ritual is repeated until the column is filled to a height of approximately 10 feet.

Once the column has been filled to capacity, a person standing on a small stepladder removes the securing collar. The column is tied off at the top using whatever means deemed most efficient (a twist-tie, knot, collar, etc.). The column is carefully taken away from the inoculation station and another tube is immediately secured for the next fill of inoculated substrate. An 8-foot-long column, 12 inches in diameter, tightly packed can weigh 120–150 pounds depending upon moisture content, density (determined largely by particle or “chop-size”), and spawn rate.

Once ferried into the growing room, the column is inverted so that the loose straw at the top is compressed. Stainless steel arrowheads are mounted on a board used to puncture 200 to 400 holes in each plastic column. Note that 75% of the weight of the column is floor-supported.

The same column 12 days later, after inoculation with grain spawn of the Pink Oyster mushroom (Pleurotus djamor). Twenty-seven pounds of fresh mushrooms were harvested on the first flush.

After the top folds of the column have been secured, the column should be inverted, upside down. The loose-filled substrate that was in the top 2 feet of the column is now at the bottom and the dense substrate at the bottom of the column is now switched to the top. This, in effect, packs the column tightly. If the straw is not tightly pressed against the plastic, causing substantial cavities, mushrooms will form behind the plastic and develop abnormally. In contrast, tight fills cause the substrate and plastic to be forcibly in contact with one another. When an arrowhead puncture is made, the plastic bursts. The mycelium is exposed to the growing room’s oxygen-rich, humidified atmosphere. Given proper lighting and temperature conditions, a population of primordia forms specific to each puncture site. Growers using this technique develop a particular fondness for strains that are site-specific to the punctures in their response to standard initiation strategies.

Once the column is removed from the inoculation station, two people carry or trolley it to the growing room, where it is hung and allowed to incubate. Overhead trolley systems similar to those employed in slaughterhouses, cold storage rooms, or even clothes dry-cleaner companies can be adapted for this purpose. If the columns are carried, care must be taken so that the columns do not sag in the middle, lest they break. Modified hand trucks fitted with a slant board are helpful in this regard.

The columns are hung to approximately 4 inches above the floor. After hanging, they noticeably stretch within a few seconds to become substantially, approximately 75% floor-supported. Columns (10 inches in diameter and greater) suspended in the air after inoculation will probably fall before the cropping cycle is completed.

Within 1 hour of the columns settling to the floor, numerous holes must be punched for aeration. If holes are not punched until the next day, substantial loss of spawn viability occurs, and a bacterial bloom ensues in the stagnant, air-deprived column. However, if the column is suspended and holes are punched too soon, the punctures elongate. The column soon is in danger of splitting apart. For an 8-foot-high column, 12 inches in diameter, at least 200 and no more than 400 ⅛-inch holes should be punched for maximum yield. Stainless steel, four-bladed arrowheads mounted on a board are recommended for this purpose. Although the puncture hole is only ⅛ inch in diameter, four slits 1–2 inches in length are also made. These flaps open as the mushrooms push through.

Bottle culture of a dark gray strain of Hypsizygus tessulatus, known in Japan as Buna-shimeji or Yamabiko Hon-shimeji. This mushroom is currently being marketed in America as just “Shimeji.” The Japanese prefer to use the Latin name Hypsizygus marmoreus for this mushroom. For more information, please consult the growth parameters for this species.

Bottle Culture

Bottle culture is an effective means for growing a variety of gourmet and medicinal mushrooms on sterilized substrates. However, bottle culture is impractical for the cultivation of mushrooms on pasteurized bulk substrates such as straw or compost. San Antonio (1971) first published a method for growing Agaricus brunnescens, the Button mushroom, on cased, sterilized grain from bottles. This article became a template for the cultivation of many other mushrooms. A counter-culture book on psilocybin mushroom cultivation by Oss and Oeric (aka Dennis and Terence McKenna, 1976) brought the concept of bottle culture to the forefront of small-scale mushroom cultivators. Currently, Asian growers have adapted bottle culture, originally designed for the easy cropping of Enoki mushrooms (Flammulina velutipes), to the cultivation of many other gourmet and medicinal mushrooms, including Lion’s Mane (Hericium erinaceus), Buna-shimeji (Hypsizygus tessulatus), Reishi (Ganoderma lucidum), Wood Ears (Auricularia polytricha), and some varieties of Oyster mushrooms.

The advantage of bottle culture is that the process can be highly compartmentalized and easily incorporated into the many high-speed production systems adapted from other industries. The disadvantage of bottle culture is that the substrate must be top-spawned and grain spawn cannot be mixed thoroughly through bottles containing sawdust substrates. The bottles are filled to within 2 inches of the brim with moistened supplemented sawdust and then sterilized for 2 to 4 hours at 15 to 20 psi. (The formula is the same for bag culture of Shiitake and Enokitake. Please refer to Chapter 21.) When grain spawn is added at inoculation, and the bottles are shaken, the spawn descends to a depth of only a few inches. Hence, the mycelium quickly covers the top surface layer and then grows slowly downwards into the sterilized sawdust. Top-spawning results in imbalanced ages with the mycelium, with the highest zones being oldest and the lowest regions being youngest. The newly growing mycelium near the bottom inhibits the formation of mushrooms in the top layer of mycelium as the life cycles are engaged in two distinct and potentially contradictory activities. The discrepancy in age in zones of the mycelial mat inhibits maximum mushroom formation. When the mycelium is actively growing out, the total mycelial colony cannot easily shift from colonization to primordia formation. Nevertheless, top-spawning will result in the entire substrate becoming fully colonized, although fruitings are delayed.

Bottle (jar) culture (cased grain) of a Magic Mushroom known as Psilocybe cubensis.

Sterilized sawdust inoculated via top-spawning.

Downwardly growing mycelium a week after inoculation into sterilized sawdust.

An advantage of this method is that mushrooms, when they do form, arise from the maturest mycelium, at the top of the bottles. Side and bottom fruitings are rare. Top-spawning is preferred by cultivators in tropical climates where air conditioning is not an economical option. With top-spawning the substrate is slowly colonized from above, and head generation is much less than from through-spawning techniques. In contrast, through-spawning gives colder climate cultivators benefits from heat generation associated with faster spawn run. If the cultivator can afford to make the initial investment of incubating thousands of bottles until the first cycle starts, then the drawbacks are primarily that of lost time and delay in the initial production cycle, but not overall yield. Top-spawning is fast and convenient for bottle and small bag culture, although I see more benefits from through-spawning. Many cultivators in Japan accelerate the colonization process by inoculating the bottles with pressurized liquid spawn.

With the natural evolution of techniques, Asian cultivators have replaced bottles with similarly shaped, cylindrical bags. Many growers in Thailand, Taiwan, and Japan prefer this hybrid method.

Liquid-inoculation of sterilized, supplemented sawdust allows for inoculation methods resembling the high-production systems seen in a soda pop factory. With reengineering, such high-speed assembly-line machinery could be retrofitted for commercial bottle and bag cultivation.

Unless an aggregate-slurry is used, liquid spawn settles near the bottom of the bottles. For a complete discussion of liquid fermentation and inoculation techniques, please refer to Chapter 15. Bottles can be arranged horizontally in walls or fruited vertically.

Bottle culture of Enoki mushrooms (Flammulina velutipes). Exposure to light caused caps to mature. The mushrooms at this stage are not marketable. They were—24 hours earlier.

Bottles of various sizes can be used. The most common are between 1 quart (1 liter) and 1 gallon (4 liters). The openings are usually between 50 and 100 millimeters in diameter. Glass bottles are not as popular as those made from polypropylene-like materials. Each bottle is fitted with foiled cotton or an autoclavable lid equipped with a microporous filter disk. After full colonization, the lids are removed, and the surface mycelium is exposed to the growing room environment. Enoki growers often insert a coil of paper or clear plastic that encourages stem elongation.

Compacted compost formed to create self-supporting “megablocks” for the cultivation of the Button mushroom, Agaricus brunnescens. This ingenious British method of cultivation is being patented (U.K. Patent #953006987.1). The cavities allow transpiration and prevent anaerobic cores.

Oyster mushrooms (Pleurotus ostreatus) fruiting from suspended, perforated plastic containers. A Russian cultivator, Vladimir Nesterov, is refining this method.

Button growers long ago discovered that, by placing a layer of peat moss over compost grown through with mushroom mycelium, yields were greatly enhanced. The casing serves several functions. Foremost, the casing layer acts as a moisture bank where water reserves can be replenished through the course of each crop. The casing layer also limits damage to the mycelium from fluctuations in relative humidity. Besides moisture, the casing provides stimulatory microorganisms and essential salts and minerals. These combined properties make casing a perfect environment for the formation and development of primordia.

Applying a peat moss casing.

One week later, mycelium grows close to the surface.

Two weeks later, primordia form in the casing layer.

In the cultivation of gourmet and medicinal mushrooms, casing soils have limited applications. Cultivators should be forewarned that green-mold contamination often occurs with soil-based casing layers, especially when air circulation is poor and coupled with contact with wood framing. The possible benefits of casing are often outweighed by the risks they pose. Few woodland species are absolutely dependent upon casing soils, with the exception of the King Stropharia (Stropharia rugosoannulata).

A dozen or so casing soils have been used successfully in the commercial cultivation of mushrooms. They all revolve around a central set of components: peat moss, vermiculite, calcium carbonate (chalk), and calcium sulfate (gypsum). Two brands called Sunshine #2 and Black Magic peat moss are preferred by many Canadian and American growers. Recently, “water crystals,” a water-capturing plastic, have been tried as a casing component with varying results. These crystals can absorb up to 400 times their weight in water and do not support contaminants, two highly desirable characteristics. Unfortunately, the fact that water crystals are not fully biodegradable and cannot be easily recovered from the spent substrate greatly limits their acceptance by environmentally inclined growers. Starch-based water absorbents tend to clump and must be added with an aggregate. Cultivators must weigh and balance these factors when designing the casing mixture.

For many years, cultivators have used the following casing formula.

Casing Formula (by volume)

Calcium carbonate is used to offset the acidity of the peat moss and should be adjusted according to desired pH levels. Calcium sulfate, a non-pH affecting salt,¹ provides looseness (particle separation) and mineral salts, especially sulfur and calcium, essential elements for mushroom metabolism. Peat moss, although lacking in nutrition, is resplendent with mushroom-stimulating bacteria and yeasts. The above-described formula depends greatly on the starting pH of the peat moss. (A pH neutral peat moss I like is Sunshine brand. It seems less prone to Trichoderma molds.) Generally, the pH of the resultant mixture is 7.5 to 8.5 after makeup. As the mushroom mycelium colonizes the casing layer, its pH gradually falls. For some of the more acid-loving species mentioned in this book, calcium carbonate should be excluded. Typically, this chalk-free mixture gives pH readings from 5.5 to 6.5. Adding 10% coca nut fiber and .5–1% salt enhaces osmosis, aeration, and transportation of water to lower regions of casing. Some European growers spawn the casing at the time of application to assure dominance, prevent contamination, and set primordia evenly.

Mix the dry components together in a clean bucket or wheelbarrow. Add water slowly and evenly. When water can be squeezed out to form brief rivulets, then proper moisture has probably been achieved. A 75% moisture content is ideal and can be tested by measuring the moisture lost from a sample dried in a hot oven.

Once wetted, the casing is applied to the top of a substrate. Casing soils can be used with tray, bag, or outdoor mound culture. Although some of the following mushroom species are not absolutely dependent upon a casing soil, many benefit from it. Those species dependent upon soil microorganisms for fruitbody formation are listed below with an asterisk. In absence of soil bacteria, the “¹” species will not fruit well, or at all. Typically, a 1- to 2-inch layer of casing soil is a placed onto 4–10 inches of colonized substrate.

(Techniques for the cultivation of Agaricus bitorquis are covered in detail in The Mushroom Cultivator by Stamets and Chilton, 1983.)

If the microclimate lacks enough air circulation and carbon dioxide builds up, contaminants (especially green molds) will flourish in peat moss–based casings. Some cultivators are discouraged from using casing soils considering the contamination potential they pose. Others, in the effort to defeat mold contaminants and kill nematodes, pasteurize or sterilize the casing mixture. By a quirk of nature, casings often encourage more contamination than they prevent.

A one- to two-inch layer of moist casing is evenly placed across the top surface of the substrate, and lightly patted down. Relative humidity is maintained at 90–95% until fans of mycelium break through the surface. At this time, a classic initiation strategy is implemented: Watering is increased; rH is raised to 95–100%; air exchange is accelerated; and temperature is dropped. (See Chapter 21.) If the casing is being placed onto substrates enveloped in plastic bags, holes must be poked on the undersides for drainage.

Here is an alternative formula, containing no contaminant-supporting ingredients.

Soil-less Casing Formula (by volume)

1 unit vermiculite

1 unit “water crystals”

Mix vermiculite and water crystals when dry. Add water until fully saturated. This mixture can hold up to 90% moisture until its carrying capacity for water is exceeded. Apply a ¼- to ½-inch layer as a casing layer to the surface of the mushroom mycelium.

The Button mushroom (Agaricus brunnescens) fruiting from cased grain.

A Magic Mushroom (Psilocybe cubensis) fruiting from cased grain.

At our farm, I have found that the spent substrate generated in the course of Shiitake cultivation is in itself a valuable by-product. More mushrooms can be grown upon it! The mushroom cultivator can implement a circuit of recycling by sequencing species on the same substrate, resulting in the maximum yield of mushrooms imaginable. Each decomposer produces its own unique set of enzymes that can only partially break down a wood-based substrate. Once the life cycle of one mushroom has been completed, the life cycle of another species can begin on the same substrate utilizing its own unique set of enzymes, taking advantage of the remaining undecomposed wood fiber and the dead mycelium of the predecessor mushroom. After this second decomposer exploits the remaining lignin-cellulose to its fullest ability, a third species can be introduced. And so on.… I have been able to grow four species in sequence with this method. After several generations of mushroom species, the mass of final substrate is a mere fraction of the original formula. The end material is reduced to a soft loam and is best used for compost or soil enhancement.

After running several species through the same substrate, Chang and Miles (1989, page 332) found that the net available nitrogen in the waste substrate actually increased, proportionately. Using cotton waste, the total nitrogen of the fresh compost waste was 0.63%. After the Paddy Straw mushroom produced on it, the residual nitrogen became 1.54%. After taking this same waste substrate and inoculating it with Oyster mycelium (P. ostreatus var. florida), the nitrogen increased to 1.99%. (The effect that spawn had on the substrate was not described. A 10% spawning rate with rye could substantially affect these figures. If “substrate spawn” were used, the net effect would be much less.) The end result of species sequencing is the production of rich humus, ideal for gardening. This concept is further incorporated into a permaculture model described in Chapter 5.

The sequence of species introduction, however, is most important. The Shiitake model is the easiest to understand. After Shiitake mushrooms stop producing on supplemented sawdust/chips, the now-blackened blocks are broken apart until they resemble sawdust in texture. Calcium sulfate and/or carbonate enhance particle separation, drainage, and adjust the pH to the 6.5 to 7.5 range. (Try 1 cup of gypsum/chalk for every twenty blocks and adjust accordingly.) The type of wood initially used becomes the overriding factor affecting proper formulation. Water is slowly added until good moisture is achieved. (I prefer moisture content of 60–65%, less than the ideal 75%. Higher moisture contents often result in a higher percentage of bags spoiling due to fermentation.) The moistened sawdust mixture is filled into polypropylene bags or other suitable containers, and sterilized. If water collects at the bottoms of the bags, then the substrate has been over-moistened.

After sterilizing, the bags are inoculated according to the procedures in this book. I have found that Oyster mushrooms grow profusely on the waste Shiitake substrate and needs little or no amendment. King Oyster and Maitake also fruit, although 10% supplementation with rice bran or corn substantially improves yields. After the second species in sequence has run its course, the waste substrate is collected, remixed, sterilized, and finally inoculated with King Stropharia (Stropharia rugosoannulata) or Shaggy Mane (Coprinus comatus). However, if the spent substrate is understerilized and/or too much water is added at makeup, contamination during incubation is likely. Keep in mind that waste substrates host far more microorganisms than fresh sawdust. Hence, sterilization may have to be prolonged to insure killing all the resident contaminants.

Each time one of the above species (except Stropharia rugosoannulata) is grown through the sterilized sawdust-based substrate, approximately 10% of the dry mass (= 25% wet weight) of the substrate yields fresh mushrooms. Depending upon the species and many other variables, between 20 and 40% of the dry mass evolves into gases, mostly carbon dioxide, nitrogen, and ethylene. The first species, in this case Shiitake, easily produces 1.5 pounds of mushrooms from the original 6-pound substrate (75% moisture). At least 1.5 pounds is lost through carbon dioxide evolution and evaporation. At the end of the Shiitake fruiting cycles, a 3-pound waste substrate remains with moisture content approaching 50%. After Oyster mushroom mycelium has taken its turn, the reduction in mass undergoes another 50% reduction in mass. Now, our sample has been reduced from an original 6 pounds to 1.5 pounds. At this stage, the remaining material, without supplementation, supports vigorous growth of the King Stropharia (Stropharia rugosoannulata) or the Shaggy Mane (Coprinus comatus). Once colonized, the mycelia of these species are best used as spawn to inoculate outdoor substrates. At this final stage, the nutritional base of the substrate is largely expired, and the fruitings are anemic.

In all, more than 20% of the substrate (dry weight to dry weight) is converted into edible mushrooms. At least that amount is liberated as gases. The remaining material can be added to garden composts as a supplement. The process of reduction/ conversion is substantially prolonged if the cultivator utilizes large-particle wood chips in the original substrate formulas. When denser hardwoods are used, the cycle is prolonged. If the waste wood substrate is further supplemented, the cycle can be extended.

This is but one path of species sequencing. Many others naturally come to mind. For instance, when production blocks of recycled Oyster, Maitake, or Reishi (or others) have stopped producing indoors, they can be implanted outdoors into beds of sawdust. Additional fruitings arise from the buried blocks in 3 to 6 months, depending, of course, upon the weather. I am always fascinated by the fact that these outdoor fruitings are often better than those indoors. Mushrooms seem to always benefit when nature is used as an ally. The implanted blocks of mycelium have the ability to draw additional nutrients from the surrounding habitat. By launching the expired blocks from the growing rooms into supportive outdoor habitats, the cultivator maximizes the potential of the mycelial mass. One of my natural culture beds supports a succession of three species—first Morels in the spring, then King Stropharia in the summer, and an assortment of Hypholoma and allied species in the fall. I see this approach as the “Zen” of mushroom growing.

Whatever path is chosen, the implications are profound. These courses of decomposition are occurring daily in our forests’ ecosystems. Ecologists should also find this model especially fascinating in understanding the concurrence of many species living in the same habitat. This model may also be useful for those living in desert, island, or other environments where substrate materials for wood decomposers are costly and hard to acquire. I encourage all readers of this book to push these concepts forward with new innovations and applications, incorporating more sets of organisms. By understanding the nuances within the mycosphere, I envision the creation of complex biospheres wherein fungi play determinant roles in supporting other life cycles. And I am not alone in believing that mushrooms can be instrumental in generating food for humans in the exploration of space.

Mushrooms can be compared to fish in their perishability. Once harvested, they are quick to spoil unless properly cared for. One advantage of growing gourmet and medicinal mushrooms is that, historically, they have been used in dried form for centuries. In Asia, more Shiitake is sold dried than fresh. Asians long ago discovered that the flavor of Shiitake is actually enhanced in drying. Further, having a readily available supply of dried mushrooms, which can be stored for months at room temperature in airtight containers with no special care, is very convenient for consumers. Because the storage problem is compounded by the lack of refrigeration in many developing countries, dried mushrooms make good sense for both producers and consumers. In the United States, Canada, and Europe, more mushrooms are sold fresh than dried. In these markets, cultivators first supply the needs of the fresh market and then dry the surplus. Dried mushrooms can be sold as is or powdered for soup mixes, spices, or teas.

Harvesting Paddy Straw mushrooms in Thailand.

Before and after cleaning the stem butts of Himematsutake, the Almond Portobello, Agaricus blazei.

Harvesting the Crop

Simple guidelines prevail in the proper harvesting and storing of mushrooms. First, young mushrooms last much longer after harvest than aged mushrooms. Once spores have developed on the face of the gills, perishability is accelerated. If mushrooms have partial veils, like the Button mushroom (Agaricus brunnescens) or the Black Poplar mushroom (Agrocybe aegerita), they are best picked while the partial veils are intact, in other words when the mushrooms are still young. Partial veils protect the gills, limiting moisture loss, preventing spore release, and rupture only as the caps expand.

The cultivator must constantly counterbalance maximum yield with marketability. The comment I most often hear, after presenting my Oyster mushrooms to a distributor who has been purchasing them from afar, is “I didn’t know Oyster mushrooms could look like this!” Because Oyster mushrooms readily suffer from shipping and handling, local producers can easily usurp the markets of distant growers. Oyster mushrooms have a functional life span of only 5 days, after which marketability drastically declines.

Another rule is that clusters yield, pound for pound, higher-quality mushrooms than mushrooms grown individually. Bouquets of mushrooms have obvious advantages, both from the point of view of harvesting as well as marketing. They can be picked with ease, needing minimum handling and trimming. Once harvested, the mushrooms protect one another by being bunched together, and as with many Oyster species, frequently are joined together from a common stem base. Harvesting mushrooms in clusters limits the damage caused by individual loose mushrooms jostling against one another. Most importantly, bouquets, at the ideal stage for harvest, are composed of younger mushrooms. Mushroom bouquets can then be sold much like broccoli. All these features combined extend shelf life far beyond that of individual mushrooms and make clusters highly desirable for most cultivators. All the gilled mushrooms described in this book can be harvested as bouquets.

Bouquets of Pleurotus ostreatus facilitate harvesting, extend shelf life, and increase marketability. The bouquets usually snap off, originating from a small, localized point of formation.

Each species passes through an ideal stage as the mushrooms mature. For most species, the ideal stage is when the caps are still convex, and before flattening out. After adolescence, the mushroom changes in its form while not appreciably increasing in its mass. Cultivators have long noted that the flesh of a mushroom at the “drumstick” stage is much thicker than when the mushroom is fully mature. The loss of flesh, directly above the gills to the top of the cap, appears to be reproportioned to the leading edge of the expanding cap, and perhaps more significantly, to the extension of the spore-producing gills. No real advantage, in terms of weight, is realized in picking a fully mature mushroom versus one that is a mature adolescent. In fact, mature adolescents store longer and taste better.

The ideal stage for harvest of each species is described in Chapter 21 under each species’ growth parameters. Please refer to that chapter for helpful hints in harvesting. Since cropping is labor-intensive, more efficient harvesting methods are always being explored. Cropping mushrooms in the most cost-effective manner largely depends on the structure of the fruiting frames. In Holland, mechanical harvesters have been devised to harvest mushrooms from horizontal beds, eliminating the largest labor contingent in a mushroom farm—the pickers.

Four strains of Pleurotus ostreatus, in 5-pound boxes, ready for delivery to restaurants.

Packaging and Storing the Crop for Market

Once mushrooms have been harvested, they must be quickly chilled. Most pickers at mushroom farms place mushrooms directly into open-grate plastic baskets that are frequently ferried to the cold room. The larger farms utilize blast chillers, which precipitously drop the temperature of the mushroom from room temperature to near freezing. The common mistake many growers make is to place their fresh mushrooms directly into cardboard boxes after picking. Cardboard boxes insulate the mushrooms after harvest; essentially preventing them from being rapidly cooled. During or after cooling, mushrooms are sorted and packaged. Once cooled, the mushrooms must not be rewarmed until delivery. The ideal temperature for storage is 34°F (1–2°C). (See Lomax, 1990 and Hardenburg, 1986.)

Mushrooms are sorted according to markets to which they are destined. The Japanese are by far the connoisseurs of the world in terms of quality standards for marketing. So strict are their standards that many North American growers have been unable to penetrate into the Japanese market. The Japanese also have the advantage of having a large pool of specialty growers who can coordinate their product lines to best fill their complex market requirements. Mushrooms are carefully graded according to type, size, and form. In North America, the markets are relatively unsophisticated and the primary concern is for freshness. Currently, in Seattle, Shiitake mushrooms are selling for $11.99 per pound at the local grocery store. With stores making a 40% markup, the grower would then be paid $7.20 per pound. In the United States, some growers, buyers, and sellers follow a loosely adhered-to grading system. Number 1 Shiitakes are usually 3–5 inches across, dark brown in color, with incurved margins, usually adorned with veil remnants. Number 2 are basically number ones that have more or less fully expanded. Number 2s are often lighter in color and exceed 4–5 inches in diameter. Number 3s show some damage, either to the gills or cap margin, and are often deformed. Number 3s vary in size from tiny to excessive large mushrooms. I find it interesting that Americans, as a culture, have historically favored large mushrooms. Currently, in markets in San Francisco, large Shiitake are selling for several dollars per pound more than small ones.

Once mushrooms are sorted to grade, they are packaged for market. Restaurants generally prefer 5- to 7-pound boxes. Packages for consumers typically weigh 3, 5, or 7 ounces, a trick employed by many marketers to disguise the actual price per pound. (It’s not easy for the consumer to divide 16 ounces (1 pound) by 3, 5, or 7 to determine the actual price per pound.) In the United States, packages of fresh mushrooms should be small enough so that they can be grasped by one hand, and ideally retail at or below $2.00. Once the sale price to the consumer exceeds the $2.00 threshold, a precipitous decline in sales is seen. If every 3-ounce package sold for $2.00, the retail price is $10.66 per pound. Most retailers consider a 40% markup fair. This gives the growers $6.40 per pound at the wholesale level.

Another tactic commonly used with Button mushrooms is to sell the mushrooms loose in a tray, and have the consumers fill small paper bags imprinted with information on handling, cooking, etc. The consumer can be more selective in picking the mushrooms most desirable. However, every time the mushrooms are rummaged through, they suffer in quality. Although Button mushrooms are often sold loose, the gourmet mushrooms, being more fragile, are best sold packaged.

Covered with clear, anticondensate, breathable plastic, mushrooms can be preserved for extended periods of time. A patent was awarded to Asahi-Dow Ltd. for a vapor-permeable film specifically designed for extending the shelf of Shiitake. [See Japanese Patent #57,163,414 (82,163,414).] The rate of diffusion of carbon dioxide giving the best results was within 5,000 and 40,000 milliliters per square meter at atmospheric pressure over 24 hours. The optimal range of oxygen diffusion was 2,000–20,000 milliliters per square meter at atmospheric pressure in 24 hours. This new generation of anticondensate, gas-permeable films must be carefully matched with a cardboard base or strawberry-like basket. Even with shelf life being extended, mushrooms should be rotated through stores at least twice weekly to ensure the highest-quality product. Oyster mushrooms in particular are quick to spoil.

The greatest insult to marketing gourmet mushrooms can be seen by vendors who buy large quantities of Oyster mushrooms from production factories whose main concern is yield, not quality. Oyster, Enoki, and other mushrooms, when they spoil, cause severe abdominal cramping, nausea, and gastrointestinal upset. (See this image / caption.) Once customers have experienced these “gourmet” mushrooms, they are unlikely to ever buy them again. Remember, mushrooms are the first suspected and first blamed for any type of food poisoning, whether they are at fault or not. (For more information on the proper handling of mushrooms after harvesting, please consult Murr and Morris, 1975.)

An example of poor packaging. Note mushrooms lie on Styrofoam base. They were covered with plastic. This package was photographed directly after purchase. This is the “sajor-caju” strain of Pleurotus pulmonarius. Thousands of primordia are forming on the adult mushrooms as they rot. Mushrooms in this condition, if eaten, cause severe cramping, diarrhea, and painful gastrointestinal discord.

A commercial dehydrator utilizing a large volume of air to remove moisture from mushrooms. Fresh mushrooms are placed onto screened shelves on wheeled racks, entering the drier downstream from the drying mushrooms. Hundreds of pounds of mushrooms can be dried at one time, inexpensively.

Drying Mushrooms

By drying mushrooms, cultivators recapture much of the revenue that would otherwise be lost due to overproduction. Most mushrooms are approximately 90% water. Reishi mushrooms, being woody in texture, are usually between 70 and 80% water. When Shiitake are grown outside, especially in the Donko (cracked cap) form, moisture content is often only 80%. When mushrooms are young, moisture contents are usually higher than when they are mature. Mature mushrooms, with their gills exposed, dry faster than young, closed mushrooms.

Shiitake, Oyster, Morel, Reishi, and many other mushrooms dry readily and can be stored for many months. Mushrooms can be sold in their natural form or powdered for soups, spice mixtures, teas, etc. Some cultivators actually sterilize their dried mushrooms, without harm, to prolong storage. Sterilization assures no bacteria, insect eggs, or other microorganisms consume the crop when stored for prolonged periods of time. Once dried, the mushrooms should be hermetically sealed, and ideally frozen until needed.

Many types of dehydrators can be used for drying mushrooms. The smallest are those also marketed for home use in the drying of fruits, meat, and fish. For most growers, home dehydrators have insufficient capacity, so many fabricate their own dehydrators. Window screens can be stacked within a vertical framework, 3–4 inches apart. At the bottom a heat source, often heat lamps or an electric coil, is positioned. Ample air inlets are located near ground level. The vertical framework is solid save for a hinged door on one face that allows easy insertion and retrieval of trays. A fan is located at the top, drawing air out of the dehydrator. This arrangement ensures a chimney effect whereby heated air is drawn through the bottom and exhausted out the top. The humidity of the incoming air greatly affects the efficiency of this type of dryer. Some growers locate their dryers in hot rooms, typically low-humidity greenhouse-like environments, which helps the drying process.

The best commercial dryer I have seen is also the simplest. Mushrooms are placed onto trays and stacked into vertical racks equipped with wheels. The wheeled racks are inserted into a large plastic wind tunnel. (See this image.) The plastic wind tunnel can be kept inflated by hoops of plastic pipe and through the force of a large blower located at one end. Trays with fresh mushrooms are moved into the wind tunnel furthest downstream. The fully dried mushrooms are retrieved through an overlapping “flap-door” nearest the fan. For most cultivators, this type of commercial dehydrator does not require a heat source. The huge volume of air removes the moisture through evaporation.

Depending upon the species and the final product desired, mushrooms can be placed gills down or gills up. If you place Shiitake mushrooms with their gills down, the mushrooms remain flatter in drying and take on a more brittle texture. Most experienced Shiitake growers find that by drying mushrooms, gills facing up, that the cap curls inwards, giving the mushroom an overall tighter and more resilient texture. This form is the one most recognized by Asians.

Dried mushrooms are then packaged, sometimes shrink-wrapped into plastic bags, and usually sold in 3- to 5-ounce packages. In most cases, the shelf life of dried mushrooms is about a year. If there is any danger of fly larvae or insect infestation, low-pressure steam sterilization is recommended.

10-kilogram bags of dried Shiitake being sold in a market in China.

Marketing the Product

In the United States, markets for fresh mushrooms have surged over the past 30 years, from a total market value of $68 million in 1969 to $665 million in 1992. Fresh gourmet mushrooms were virtually unavailable in 1980. In 1992, gourmet mushrooms represented $17 million of total fresh mushroom sales, a 22% increase over the same period from the previous year. The per capita consumption of mushrooms continues to rise in the United States, going from 3.70 pounds per capita in 1990 to 4.10 pounds in 1999. Although Canada consumes 50% more mushrooms per capita than in the United States, the rate of increase in consumption in the U.S. is more than double Canada’s. In 1999 specialty mushroom consumption in the United States (excluding Portobellos) increased 35% from the previous year, with Shiitake representing 66% of that market. For updated information please consult United States Dept. of Agriculture Market Reports at usda.mannlib.cornell.edu/reports/nassr/other/zmu-bb/ and the United Nations Food and Agricultural Organization at usda.mannlib.cornell.edu/data-sets/specialty/94003. (Approximately four times more Shiitake are sold in this country than Oyster mushrooms.) The upward trend in terms of price, production, diversity, and markets is expected well into the future.¹

Before producing mushrooms on a commercial level, the cultivator is advised to conduct mini-trials. With a little experimentation, the cultivator can refine their techniques. Each failure and success is useful in determining the proper mushroom strain, substrate formula, temperature tolerance, lighting level, harvesting methods, and marketing strategies. Note that yields from mini-culture experiments often exceed average values from commercial scale operations. I strongly encourage cultivators to increase their production levels slowly, and according to their skills in both mushroom technology and business management.

A number of organizations help growers find markets for their mushrooms. Some co-operative marketing organizations coordinate production and sales. Co-op marketing becomes a necessity when multiple growers overwhelm local markets. (Refer to the Resource Directory, Appendix 4 for a list of some marketing organizations.) The United States Department of Agriculture can sometimes assist growers in contacting marketing outlets.

I am a strong believer in growing mushrooms organically. Once certified organic, local producers can sell mushrooms to natural food co-ops and some upscale grocery chains for a premium. The restaurant trade, from my experience, seems little impressed whether or not the mushrooms are organically grown. In either case, the key to the financial success of a mushroom farm centers on its ability to market mushrooms successfully. The person in charge of marketing must foster a close, professional, and personal relationship with the buyers.

In Asia, marketing gourmet mushrooms has benefited from a long tradition while in North America, gourmet mushrooms are a relatively new phenomena, having been available for less than thirty years. (See Farr, 1983.) With more growers coming into production, the markets are likely to fluctuate in response to the sudden increase in the availability of mushrooms. Cycles of over- and underproduction are typical in any new, expanding marketplace and should be expected. Growers must adapt their production schedules and product lines so they do not become overextended. As the public becomes increasingly aware of the health stimulating properties of mushrooms, markets should expand enormously. Those growers who are able to survive this early period of market development will become key players in an industry that is destined to become a centerpiece of the new environmental economy.

Versatile, tasteful, and nutritious, gourmet mushrooms enhance any meal. Multidimensional in their flavor qualities, mushrooms appeal to both vegetarians and meat-eaters. The following recipes can be used with almost any of the mushrooms described in this book. The simplest way to prepare gourmet mushrooms is in a stir-fry (à la wok) at medium-high heat with light oil and frequent stirring. Other condiments (onions, garlic, tofu, nuts, etc.) can be added after the mushrooms have been well cooked.

Here are some of the favorite recipes from notable mushroom dignitaries. I hope you enjoy these recipes as much as I have. For more recipes, please consult the references listed at the end of this chapter. Bon appetit!!!

Our family prefers to tear Shiitake rather than cutting them. This preserves flavor and minimizes damage to the cells.

David Arora’s Mediterranean Mushroom Recipe

“Nothing could be simpler or more delicious,” according to David.

Choose the meatiest caps of King Stropharia (young), Oyster, Hon-Shimeji, or Shiitake mushrooms, lightly salt the gills, and dab them with olive oil. Stuff slivers of shallots or garlic between a few of the gills. Broil or grill the mushrooms over hot coals for a few minutes on each side, until tender.

Arleen and Alan Bessette’s Dragon’s Mist Soup

In a saucepan, sauté mushrooms in vegetable oil over medium-low heat for approximately 5 minutes. Add broth, water, and garlic; bring to a boil, reduce heat and simmer 10 minutes. Add all remaining ingredients except sesame oil. Return to boil, reduce heat and simmer 5 minutes. Just before serving, stir in sesame oil. Serves 4.

Jack Czarnecki’s Shiitake in Burgundy Butter Sauce¹

In a skillet, sauté the onions in the butter until transparent, then add water. Add the other ingredients, except the mushrooms and cornstarch, and stir for 1 minute. Add the mushrooms, and turn the heat to low. Cover the skillet with a tight-fitting lid, and let simmer for 30 minutes. Thicken the mixture with the cornstarch-and-water mixture, and serve alone or over rice. According to Jack, the sauce actually enhances the flavor of the Shiitake. Serves 4.

Jack Czarnecki’s Chicken with Oyster Mushrooms¹

Combine all the ingredients except the cornstarch mixture in a heavy skillet. You may also want to save the salting until the dish is slightly heated. Heat until simmering over a medium flame, then continue simmering over a low flame for 5 minutes. Thicken with the cornstarch-and-water mixture, and adjust for salt as necessary. Serves 2.

Larry Lonik’s Morel Quiche²

Preheat oven to 400°F (200°C). In a 10-inch, lightly greased pie pan, mix bacon, mushrooms, onion, green pepper, and cheese. In medium-sized bowl, add milk, Bisquick, eggs, salt, and pepper. Beat until smooth. Pour into pie pan. Bake 35–40 minutes or until inserted toothpick comes out clean. Serves 2 to 4.

Irene and Gary Lincoff’s Pickled Maitake (Hen-of-the-Woods)

Marinade:

Clean 1 pound of mushrooms and separate the “leaves” of Maitake into bite-sized pieces. Throw them in boiling water for 2 minutes, drain, and let cool on paper towels.

Combine marinade ingredients and season with a sprinkle of salt, peppercorns, bouquet garni, or other preferred spices. Bring marinade to a boil and cook the mushrooms in the marinade until done to taste (crunchy to soft).

Remove mushrooms. Discard solids from marinade. Store mushrooms covered with marinade in glass jars, with a thin layer of olive oil on top to help preserve. Store refrigerated. 4 to 8 servings.

(The Lincoffs wish to thank Jean-Paul and Jacqueline Latil for this recipe.)

Hope and Orson Miller’s Hot Mushroom Dip Especial

Chop mushrooms quite fine and sauté in pan with butter and lemon juice. Let simmer 5–10 minutes. Add onions, sour cream, bouillon, salt, and pepper. Simmer 5–10 minutes more. Make a paste of the remaining butter and flour. Add to hot mixture and stir until thickened. Serve hot, in fondue pot or chafing dish, with chips, crackers, or fresh vegetables. (Note: If thickened with seasoned breadcrumbs, fresh dill may be added as filling for Mushroom Squares. Use crescent roll dough. Pat the dough into a small 9-inch-square baking pan, spread filling and cover with more dough. Bake 20–30 minutes at 375°F. Cut into squares and serve hot.) Hope has prepared this dish to the kudos of mycologists throughout the world. Serves 2 to 4.

Scott and Alinde Moore’s Cheese-Mushroom Quiche

Cover bottom of pie crust with grated Swiss cheese. Meanwhile, sauté butter, onions, mushrooms, salt, pepper, and thyme. Add the sautéed ingredients to the pie crust. Beat together the remaining five ingredients and pour over mushroom layer in piecrust. Sprinkle with paprika. Bake at 375°F (190°C) for 40–45 minutes, or until center is firm. Serves 2 to 4.

Maggie Roger’s Oyster Mushrooms with Basmati Rice and Wild Nettles

Serve over basmati rice, fluffy white rice, or lightly toasted sourdough bread cubes. Serve with steamed wild nettles or freshly steamed asparagus on the side and a clear light wine. “Friends will chirp with satisfaction once they get over the wildness of it all.” Serves 2 to 3.

From Maggie’s notes: At the time you’re finding spring Oyster mushrooms, the wild nettles are about to flower and ready for picking. Use leather gloves or native wisdom to keep from getting stung. Break off just the top three leaf levels of each stalk. Prepare them by rinsing in cold water, steaming over boiling water for 7 minutes and lightly salting and peppering them. (You can pick nettles in the spring, blanch for 6 minutes, and freeze several packages for future use.) If served as below, no melted butter is needed; they have their own flavor.

Sauté mushrooms in butter or olive oil with scallion, celery, and carrots. Let simmer in its juices for 10 minutes or until slightly reduced. Add basil, thyme, sherry, turkey bits, bouillon granules, and simmer for another 10 minutes. Taste, add salt and freshly ground pepper as needed.

Make a thickening of the water and flour (or cornstarch). Stir into mushroom mixture slowly and let simmer for another 5 minutes or more, or until thickened, stirring occasionally.

Just before serving, add the half-and-half, simmer for 5 minutes or so, then pour into a warmed bowl.

Robert Rosellini’s Broiled Rockfish in an Oyster or Shimeji Mushroom and Ginger Sauce

The following recipe uses a yellow-eye rockfish from the Pacific Northwest, which is firm and delicately textured with a low fat content. The absence of fat in this particular fish provides its “clean” and pure quality. The following recipe is quick, simple, and easy for home preparation.

Brush the fillet of fish with oil and broil (or bake at 450°F) until the translucent flesh turns opaque, 7–10 minutes. Remove fish from broiling pan, place the same pan on oven burner at high heat, and deglaze pan with white wine. When wine has been reduced by two-thirds, add sliced mushrooms and preserved ginger. Sauté for about 1 minute, add butter, and swirl ingredients together until butter forms a smooth texture, about 16–20 seconds. Remove immediately and pour over fish fillet.

Note: Achieving the smooth texture with butter requires practice to avoid breaking the butter. Once this simple technique is accomplished, there are many variations of this recipe procedure. Butter contains half the fat content of most oils, and thus these recipes should be consistent with low-fat dining strategies. Serves 2.

Paul and Dusty’s Killer Shiitake Recipe

Once in a while, you come across a simple recipe that elicits enthusiastic exclamations of joy. Recently we came up with one. We get inundated with requests for it. So here it is.

Mix the oils, tamari, wine, and spices in a small bowl. Stir vigorously as the ingredients tend to separate. Set aside.

Cut the mushroom stems from the caps. Place gills facing up. Do not slice mushrooms! (The stems can be dried and used for a soup base or discarded.) Baste the sauce onto the gills of the mushrooms, making sure the gills become saturated with the sauce.

In a 350°F oven, bake mushroooms uncovered for 30–40 minutes. Or you can barbecue on an open grill. The smoky flavor makes it even better. Serve hot with seafood, rice, pasta, or whatever. Unbelievably good. Yum! Serves 2–4.

Fresh Shiitake Omelet

Mix the eggs and water in a large bowl and beat thoroughly. Add tamari to mushrooms and sauté in a frying pan with oil until water is cooked out. Add onions and garlic, cook for 1 minute, then add cashews. In a medium-sized skillet, spray a thin coat of oil or butter, add egg mixture and cook for 1 minute. Add layer of cheese. Pour mushroom mixture over the cheese. Fold over and cook for 2–3 minutes. Add salt and pepper to taste. Serves 4.

Larry Stickney’s Morel Crème Superieur

Larry’s recipe is quick and easy, ideal for tasting Morels at primitive campsites during remote Morel forays in the mountains. “Only the medically forbidden should entertain thoughts of dietary restraint during the brief Morel season when long, hard hours in the forest set up a healthy appetite in the wake of massive calorie burning and likely liquid deprivation.… Delectation is soon at hand.” He makes no note for those athletically inclined Morel cultivators who must walk from their house to their backyard to harvest Morels. Presumably, the same advice holds.

Warm cream and butter over a camp stove or wood fire in a small pot. Do not let cream burn onto the pan’s bottom. When the cream simmers, place the sliced Morels into pot, and cook until cream returns to a simmer for at least 5 minutes. Morels should not become limp before tasting, using toothpicks or forks to retrieve them. After the last Morel is removed, Larry notes that lots must be drawn to determine the lucky soul who has the privilege of downing the heavenly, rich, spore-darkened cream soup. Serves 2 to 4.

Andrew Weil’s Shiitake Teriyaki

Reconstitute 1 cup dried Shiitake by covering with hot water and let stand till caps are completely soft. (Or cover with cold water, microwave on high for 2 minutes, and let stand.) Cut off and discard stems. Squeeze excess liquid from caps and slice into ¼-inch pieces. Place pieces in saucepan with sake, soy sauce, and brown sugar. Bring to boil and simmer, uncovered, till liquid is almost evaporated, tossing mushrooms occasionally. Remove from heat, cool, and chill. Sprinkle with finely chopped scallions and a few drops of dark (roasted) sesame oil. Serve as appetizer, side dish, or over rice.

Shiitake or Maitake Clear Soup

Soak cut or broken dried mushrooms in 2 cups cold water for 15 minutes. Drain off broth and save. Cover mushrooms with more cold water and soak for another 20 minutes. Add saved mushroom broth back into preparation and boil it for a few minutes. Season soup with soy sauce and miso. Add tofu and onions. (If needed, add 1–2 cups more water.) Bring back to a boil for 1–2 minutes and turn down heat. Allow to simmer for 5 minutes. Serves 4.

Shiitake Hazelnut Vegetarian Pâté⁴

Trim and discard woody ends from mushrooms. In a food processor, finely chop mushroom caps and stems. In medium skillet, melt butter. Add mushrooms and garlic and sauté for at least 5 minutes. Stir in thyme, salt, and pepper. In food processor, chop parsley. Add hazelnuts and process. Add Neufchâtel cheese and process until smooth. Add sherry and mushroom mixture. Process until well mixed. Spread or mold in serving dish. Cover. Chill at least 1 hour. Serve with crackers. Yield: 1 cup. (Other mushrooms can be substituted for or combined with Shiitake.)

Maitake “Zen” Tempura

This recipe can also be used as a base to make tempura shrimp, whitefish, and/or assorted vegetables (zucchini, potatoes, onions, etc.).

If using dried Maitake, soak cut or broken mushrooms in 2 cups cold water for 15 minutes. Discard water. Cover mushrooms with more cold water and soak for another 20 minutes. Drain and discard water. In a separate bowl, mix flour with eggs and cold water. Dip and roll the mushrooms into the flour/egg mixture. Deep-fry the Maitake mushrooms in hot oil (356°F / 180°C) for 1 minute. Remove any damp excess oil with paper towel. Serve with tempura sauce. Serves 2.

Stuffed Portobello Mushrooms

Remove the stems from the portobellos, chop and reserve. Place the whole mushroom caps smooth side down on a lightly greased baking sheet and bake in a preheated 425°F (220°C) oven for 15 minutes. Meanwhile, heat the oil in a skillet over moderate heat and sauté the mushroom stems, bell peppers, onion, scallions, and garlic until tender, 8 to 10 minutes. Add the herbs and cook an additional 2 minutes. Spoon the vegetable mixture into the mushroom caps and top with the cheese. Bake an additional 10 minutes, or until the mushrooms are tender and the cheese has melted. Sprinkle with sliced scallions and serve immediately. Serves 4 (2 mushrooms per person).

Recommended Mushroom Cookbooks

This troubleshooting guide should be used in conjunction with the Growth Parameters for Gourmet and Medicinal Mushroom Species (Chapter 21) and the Six Vectors of Contamination described in Chapter 10. Individual contaminants are not specifically characterized in this book. If the vector introducing contamination is blocked using the techniques described here, the competitor organisms are effectively stopped. For extensive descriptions on contaminants, please refer to The Mushroom Cultivator by Stamets and Chilton (1983) and The Pathology of Cultivated Mushrooms by Houdeau and Olivier (1992).

The following guide lists the most frequently encountered problems, their probable causes, and effective solutions. A combination of solutions can often solve problems whose causes cannot be easily diagnosed. Most can be prevented through process refinement, structural redesign, improvement in hygiene maintenance, and/or replacement of personnel. Most importantly, the manner of the cultivator has the overriding influence on success or failure. I strongly encourage that, at every stage in the cultivation process, the cultivator leaves one petri dish, spawn jar, sawdust bag, etc. uninoculated to help determine whether or not ensuing contaminants are unique to the media preparation process versus the inoculation method. These “blanks” are extremely helpful in diagnosing the probable vector of contamination.

Cultivators should note that when one error in the process occurs, many symptoms could be expressed. For instance, diseases attacking mature mushrooms are to be expected if the humidity is maintained at too high levels during cropping. If the growing room is kept at 100% RH, the surfaces of the mushrooms remain wet and become perfect environments for parasitic fungi and bacteria. Bacterial blotch attacks developing mushrooms. Green molds proliferate. Mites eat mold spores. Flies carry mites and spores. If these organisms spread to developing primordia, massive deformation and contamination ensues. Those mushrooms that do survive have exaggeratedly short shelf lives after harvest. So, in this instance, one problem—humidity being too high—results in multiple symptoms. The lesson here: What is good for one contaminant is good for many! Controlling the vector of contamination must be coupled with creating an environment more conducive to the growth of mushrooms than competitors.

Population explosions of Sciarid and Phorid flies defeat Oyster mushroom cultivators more than any other competitor. Fly control measures have ranged from simple sticky pads to the use of chemical pesticides, a recourse I abhor. The use of chemical pesticides, although rampant among many “old school” cultivators, is totally unnecessary for gourmet and medicinal mushroom cultivation given a balance of preventative measures. Several biopesticides have been successfully used for prevention of fly maturity. Two are notable: a parasitic nematode, Steinernema feltia, which attacks the fungus fly larvae, and the well known bacterium, Bacillus thuringiensis, aka “BT-14.” Applications are typically weekly, and are especially useful for those using manure-based substrates, or whenever a casing layer is applied.

A highly effective bug trapper. The circular light attracts flies to the vacuum-vortex that throws the flies into a clear plastic bag. By attaching “sticky paper” underneath the light, hovering flies are also captured. The clear bag allows the easy, daily counting of flies and helps predict impending outbreaks.

Bug lights should be positioned at the entrance of every door. The bug traps I find that work the best are those that feature a circular black light and centrally located fan that creates a negative pressure vortex, features that greatly extend their effective range. These bug lights should also have sticky pads affixed below them that trap “fly-bys” or “near-misses.” Coupled with the frequent washing down of the growing room, at least twice a day, population explosions can be forestalled or precluded.

There is one final control measure I recommend highly and that occurred naturally in our growing rooms. For the past 5 years, our growing rooms have sustained a population of small tree frogs. The only food source for the frogs, which have ranged in number from 2 to 8 in a 1,000-square-foot growing room, are flies. Each frog consumes between 20 to 100 flies per day. The growing rooms—with their resident flies and frogs—are in a state of constant biological flux, readjusting to maintain a delicate equilibrium. When the fly population declines, so do the frogs, and vice versa. An unexpected and purely aesthetic benefit: At night, the frogs’ chorus while sitting on the mushrooms has a mesmerizing resonance that is joyful to hear. I consider these frogs to be faithful guardians, deserving respect for their valiant efforts at fly feasting, an activity that has an immediate beneficial impact in protecting the mushroom crop and limiting the spread of disease.¹

My growing rooms have harbored a resident population of tree frogs for more than 10 years. Each frog consumes dozens of fungus gnats each day. I highly recommend frogs as an effective and natural method for limiting fly infestation. In this case, a frog lies in wait, perched upon Reishi mushrooms fruiting from a decomposing copy of The Mushroom Cultivator.

Agar Culture

 

Problem:  Media will not solidify

Cause:  Not enough agar

Solution:  Add more agar >20 grams/liter

Cause:  Insufficiently mixed

Solution:  Agitate before pouring

Cause:  Bacteria

Solution:  Increase sterilization time to at least 30 minutes at 15 psi

Problem:  Spores will not germinate

Cause:  Inviable spores

Solution:  Obtain fresh spores

Solution:  Soak in 5 cc of sterilized water for 48 hours; place one drop of spore solution per petri dish

Cause:  Improperly formulated media

Solution:  See this description

Problem:  Spores germinate with mold contaminants (“powdery mildew”)

Cause:  Contaminated spores

Solution:  Isolate and transfer “white spots” from one another to new media dishes; always move mycelium away from competitors

Problem:  Spores germinate with bacterial contaminants (“slime”)

Cause:  Contaminated spores

Solution:  Use antibiotic media (¹/₁₅–¹/₂₀) g/liter of gentamycin sulfate)

Solution:  “Sandwich” spores between two layers of antibiotic media; isolate mycelium when it appears on top surface

Problem:  Mycelium grows, then dies back

Cause:  Poor media formulation

Solution:  See this description

Cause:  Over-sterilized media

Solution:  Sterilize for less than 1 hour at 15 psi

Cause:  Poor strain

Solution:  Acquire new strain

Problem:  Contaminants appear along inside of petri dish

Cause:  Contamination airborne in laboratory

Solution:  Filter lab air, clean lab

Solution:  Look for source

Solution:  Wrap edges of petri dishes with tape of elastic film after pouring and after inolculation

Problem:  Contaminants localized to point of transfer

Cause:  Culture contaminated

Solution:  Isolate new culture

Cause:  Scalpel contaminated

Solution:  Flame-sterilize scalpel longer

Problem:  Contaminants appear equally over the surface of agar media

Cause:  Airborne contamination

Solution:  Filter air and use good sterile technique

Cause:  Contaminated media— insufficient sterilization

Solution:  Increase sterilization time

Cause:  Hands upstream of cultures during inoculation in airstream of laminar flow hood

Solution:  Keep hands downstream of inoculation site

Problem:  Media evaporates, cracks, before colonization is compelte

Cause:  Humidity too low

Solution:  Increase lab RH to 50% or wrap petri dishes with tape or elastic film

Cause:  Culture in airstream

Solution:  Place cultures outside airstream

Grain Culture

Problem:  Grain spawn contaminates before opening, before inoculation

Cause:  Bacteria endemic to grain

Solution:  Soak grain overnight to trigger endospores into germination, making them susceptible to heat sterilization

Cause:  Contaminants enter during cooldown

Solution:  Filter air during cooldown or open pressure vessel at 1 psi in clean room

Problem:  Mycelium does not grow

Cause:  Too dry

Solution:  Over-sterilized; cook 1–2 hours at 15 psi

Solution:  Reduce surface area or porosity of filter media

Cause:  Bacterial contamination

Solution:  Soak grain spawn overnight

Solution:  Boil grain in a cauldron before sterilization

Cause:  Over-sterilized

Solution:  Reduce sterilization time

Cause:  Culture not receptive to media formula

Solution:  Alter media formula

Problem:  Mycelium grows but spottily/incompletely

Cause:  Insufficient distribution of mycelium through grain

Solution:  Shake jars with greater frequency

Cause:  Insufficient inoculation rate

Solution:  Increase amount of mycelium placed into each grain jar

Cause:  Bacterial contamination

Solution:  Clean up strain

Solution:  Increase sterilization time of grain

Problem:  Grain spawn difficult to break up

Cause:  Over-incubation

Solution:  Use spawn sooner

Cause:  Excessive water

Solution:  Reduce water in formula by 10–20%

Solution:  Use different type of grain; use rye or wheat, not millet

Solution:  Add gypsum

Problem:  Grain spawn appears pure, but contaminates with mold or bacteria after inoculation

Cause:  Mycelium endemically contaminated—coexisting with other organism(s)

Solution:  Return to stock cultures or clean strain

Cause:  Over-incubation

Solution:  Use spawn sooner; normal for old spawn to eventually support other microorganisms

Cause:  Underside of filter laden with organic debris, providing a medium for contamination to grow through

Solution:  Soak filter disks in bleach solution in between spawn runs

Cause:  Contamination airborne or from lab personnel

Solution:  Install micron filters; observe good sterile technique

Problem:  Jars crack/Bags break

Cause:  Radical fluctuation in temperature and/or pressure

Solution:  Reduce temperature and pressure flux

Cause:  Inadequate quality

Solution:  Acquire higher-quality heat-tolerant jars and bags

Straw Culture

Problem:  Mushrooms fail to form

Cause:  Improper initiation strategy

Solution:  Consult chapter 21; alter moisture, temperature, light, CO2, etc.

Cause:  Bad strain

Solution:  Obtain younger strain of known vitality and history

Cause:  Chlorinated or contaminated water

Solution:  Use activated charcoal water filters to eliminate chemical contaminants

Problem:  Mycelium produces aborted mushrooms

Cause:  Poor fruitbody development strategy

Solution:  Consult chapter 21

Cause:  Bad strain

Solution:  Obtain younger strain of known vitality and history

Cause:  Mite contamination

Solution:  Discard, disinfect, and begin anew

Cause:  Nematode contamination

Solution:  Minimize contact with soils and increase pasteurization time

Cause:  Insect damage from developing larvae

Solution:  Shut down growing room, “bleach bomb” for 24 hours, install bug lights and/or frog population, and refill with new crop

Problem:  Second and third crops fail to produce substantially or at all

Cause:  Anaerobic contamination in core of substrate

Solution:  Increase aeration or decrease depth of substrate mass

Cause:  Growing room mismanagement

Solution:  Better management

Cause:  Bad strain

Solution:  Acquire better strain

Cause:  Insufficient spawning rate

Solution:  Increase spawning rate

Problem:  Green and black molds appearing on straw

Cause:  Insufficient pasteurization

Solution:  Increase pasteurization time

Cause:  Prolonged exposure to elevated carbon dioxide levels

Solution:  Lower CO₂ levels—increase air exchange

Cause:  Incubation at too high a temperature

Solution:  Lower incubation temperature

Supplemented Sawdust Culture

Problem:  Mycelium fails to grow through within 2 weeks

Cause:  Bags inoculated too hot

Solution:  Allow to cool before substrate is inoculated

Cause:  Insufficient spawning rate

Solution:  Increase spawning rate

Cause:  Inadequately mixing of spawn through sawdust

Solution:  Increase mixing and/or spawn rate

Cause:  Mismatch of mycelium and wood type

Solution:  Use woods native to mushrooms

Cause:  Sawdust too dry

Solution:  Increase moisture

Cause:  Sawdust over-sterilized

Solution:  Reduce sterilization time

Problem:  Mycelium grows and then stops. Often accompanied by foul odors, slimy fluids. Yellow, green or black molds

Cause:  Presence of contaminants— bacteria or molds

Solution:  Consult chapter 10: The Six Vectors of Contamination

Cause:  Inadequate sterilization

Solution:  Increase sterilization time

Cause:  Sterilization sufficient but contaminated during cooldown

Solution:  Filter air during cooldown, check autoclave seals, drains, etc.

Cause:  Grain or sawdust spawn infected

Solution:  Use pure spawn

Cause:  Person inoculating introduced contaminants

Solution:  Adhere to good sterile technique

Cause:  Bags not separated to allow heat loss during incubation

Solution:  Space bags 2 inches apart, maintain air temperature at 75°F (24°C)

Cause:  Airborne contamination

Solution:  Use HEPA filters and good sterile technique

Cause:  Excessive carbon dioxide levels during incubation (>25%)

Solution:  Increase surface area, or transpiration rate of filter media

Cause:  One of the above

Solution:  Incubate the bacterially contaminated bags at 40–50°F (4–10°C) for month (40–100% are often salvageable)

Pre-Harvest Period

Problem:  Mycelium grows but fails to produce mushrooms

Cause:  Monokaryotic strain— absence of clamp connections

Solution:  Mate with compatible monokaryons—check for clamp connections

Cause:  Bad strain

Solution:  Acquire new strain

Cause:  Mismatch of strain with substrate formula

Solution:  Redevise substrate formula

Cause:  Virus/bacteria/parasitic fungi/nematodes

Solution:  Regenerate spawn from clean stock cultures

Cause:  Inhibited by environmental toxins

Solution:  Remove source of toxins

Harvest Stage

Problem:  Mushrooms form, but abort

Cause:  Bad strain

Solution:  Acquire new strain

Cause:  Poor environmental conditions

Solution:  Consult chapter 21 for species

Cause:  Competitors: molds (Mygogone, Verticillium, Trichoderma) and bacteria

Solution:  Consult chapter 10: The Six Vectors of Contamination

Solution:  Imbalanced growing room environment; CO₂ and RH too high; consult chapter 21: Growth Parameters for Gourmet and Medicinal Mushroom Species

Solution:  Mist mushrooms with water containing ½ teaspoon of elemental sulfur per gallon; equivalent to 1 lb. sulfur per 100 gal. of water

Cause:  Chemical contamination from solvents, gases, chlorine, etc.

Solution:  Remove toxins

Problem:  Mushrooms form, but stems are long; caps underdeveloped

Cause:  Inadequate light

Solution:  Increase or adjust light to correct wavelength

Cause:  Excessive CO₂

Solution:  Increase air exchanges

Problem:  Massive numbers of mushrooms form; few develop

Cause:  Poor strain

Solution:  Obtain better strain

Cause:  “Over-pinning”

Solution:  Shorten primordia formation period

Cause:  Lack of oxygen, inadequate light

Solution:  Adjust according to the species’ growth parameters; see chapter 21

Cause:  Inadequate substrate nutrition

Solution:  Reformulate

Cause:  Dilate spawning rate

Solution:  Increase spawning rate

Problem:  Mushrooms deformed

Cause:  Competitor organisms (Mycogone, Verticillium, bacteria, etc.)

Solution:  Rebalance growing room environment to favor mushrooms and disfavor competitors

Cause:  Inadequate air circulation

Solution:  Increase air circulation

Cause:  Excessive humidity or watering

Solution:  Reduce humidity to prescribed levels; surface water must evaporate from mushrooms several times per day

Cause:  Bad strain

Solution:  Acquire better strain

Cause:  Chemical contamination

Solution:  Remove toxins

Problem:  Mushrooms produced on first flush, fail to produce subsequent flushes

Cause:  Inadequate substrate nutrition

Solution:  Reformulate

Cause:  Competitors

Solution:  Consult chapter 10: The Six Vectors of Contamination

Cause:  Window of opportunity missed

Solution:  Reinitiate

Cause:  Mycelium “panned”

Solution:  Disturb substrate: break apart and repack, allow to recover and reinitiate

Cause:  Poor growing room management

Solution:  Improve management

Cause:  Bad strain

Solution:  Acquire new strain

Problem:  Flies endemic to growing room

Cause:  Inadequate pasteurization

Solution:  Extend pasteurization period

Cause:  Open doors, vents, etc.

Solution:  Improve seals at doors and windows

Cause:  Poor growing room maintenance

Solution:  Wash down growing room 2–3 times per day; place 1 cup bleach in drain to kill flies, once per day

Cause:  Slow cycling of crops

Solution:  Increase crop rotation

Cause:  Inadequate cleanup of growing rooms between “runs”

Solution:  Remove debris, wash ceilings, walls, and floors using bleach solution

Solution:  “Bleach bomb” for 24 hours

Solution:  Bug traps

Solution:  Frogs

Post-Harvest

Problem:  Mushrooms quick to spoil

Cause:  Mushrooms too mature when harvested

Solution:  Harvest when younger

Cause:  Mushrooms too warm before packaging

Solution:  Chill mushrooms before placing in marketing containers

Cause:  Mushrooms too wet when harvested

Solution:  Reduce humidity several hours before harvesting

Cause:  Mushrooms improperly packaged

Solution:  Mushrooms need to breathe; cellophane or anticondensate, gas-permeable wrapping films recommended

Cause:  Mushrooms stored beyond shelf life

Solution:  Sell mushrooms sooner

Ceramic sculpture depicting mycophiles dancing around a sacred mushroom from Colima, western Mexico, circa 100 B.C.

For you to best understand the individual components making up a mushroom farm, a comparative description of the environments and activities occurring in each room is helpful. Some rooms can accommodate more than one activity, as long as schedules do not conflict. This list is especially useful for designers, architects, and engineers who are employed to design a complete facility. Since I do not employ caustic chemicals, pesticides, and other toxins, these descriptions may not fully address the needs of farms that handle manure-based substrates and use toxic remedies.

The Laboratory Complex

Ideally a specially constructed building or a space within an existing building is retrofitted with the following parameters in mind. Please refer to Appendix 2 for more information on the necessary equipment and rules of behavior within the laboratory environment.

Purposes: To isolate and develop mushroom cultures.

To generate pure culture spawn.

Facility: A building well separated from the growing room complex

Maximum Temperature: 80°F (26–27°C)

Minimum Temperature: 70°F (21–22°C)

Humidity: 35–50%

Light: 500–1,000 lux

Insulation: R16–R32

Positive Pressurization: Yes, through HEPA filters

Additional Comments: Ideally, the laboratory should be uphill from the growing rooms so that passage of spawn is aided by gravity as it is transported. The laboratory is a relatively dry environment, encouraging the growth of mycelium only in protected containers (petri dishes, jars, and bags). Condensation surfaces must be minimized. After construction, every seam should be sealed with silicone caulking.

Floor plan of a mushroom spawn laboratory. Most of the substrate enters the clean room through the autoclave (midway left). Spawn is exported from laboratory to the growing rooms. Spawn is rotated frequently out of the laboratory.

The Growing Room Complex

The growing room complex can house all nonlaboratory activities within one building. Each room has different requirements according to their functions. These recommendations should be used as general guidelines, subject to amendment. Growers in humid tropical requirements face a set of problems uniquely different from growers in cold, temperate climates. Ancillary storage and shop maintenance buildings are not listed.

Environment 1: The Growing Rooms

Purpose: To grow as many mushrooms as possible

Facility: Rooms vary in size from 10 × 20 feet to 40 × 100 feet with 10- to 20-foot ceilings and are usually rectangular in shape with large doors at both ends. Growing rooms should have cement floors with large drains and be equipped with water and/or steam lines. Electrical boxes and lights must be waterproofed. Internal walls should be constructed of non-degradable materials. Use of wood should be minimized. Entries into each room should be 8–16 feet wide to allow for easy access using forklifts or other equipment. Inside surfaces should be made with exterior, weather-resistant materials.

Maximum Temperature: 80°F (26–27°C)

Minimum Temperature: 45°F (7–9°C)

Humidity: 50–100%

Light: 50–1,000 lux

Insulation: R8–R16 or as needed

Positive Pressurization: Yes, through electrostatic filters

Additional Comments: Ideally, a flow-through design is followed, both in consideration of fresh mushrooms as well as the entry and exit of substrate mass. Removing contaminated substrates into the same corridor through which freshly spawned substrate is being transferred causes cross-contamination. Spent substrate should be exited out of the opposite end of the growing rooms. Many farms bring their fresh mushrooms into the main hallway, en route to the sorting and cold storage rooms.

Environment 2: The Spawning Room

Purpose: A room adjacent to the pasteurization chamber wherein inoculations into bulk substrates are conducted.

Facility: The room must be constructed of materials that will not harbor mold colonies and can be washed down with ease. The height should be sufficient to accommodate the unloading of the steam box, conveyors (if used), elevated platforms and funnels for filling columns (12–16 feet). Cement floors and moisture-proof electrical fixtures are essential for safety.

Exteriorly located, air filtration system for the laboratory. This configuration allows the filtration, heating, and cooling of incoming and recirculated air. The filters must be removed periodically for cleaning and/or replacement.

Floor plan of standard growing-room complex. This configuration allows for 6 growing rooms and processing areas to be housed under one roof.

Two modified gothic-shaped greenhouses supplied by central air system.

Maximum Temperature: 90°F (32–33°C)

Minimum Temperature: Ambient

Humidity: Fluctuating from ambient to 100%

Light: 200–500 lux. Needed only for ease of personnel—skylights or moisture-proof fluorescents

Insulation: None needed

Positive Pressurization: Yes, through HEPA filters

Additional Comments: Once this room is thoroughly washed down with a dilute bleach solution prior to spawning, the fan/filter system is activated for positive pressurization. The filtration system is ideally located overhead. Air is passively or actively exhausted near the floor. During inoculation, this room becomes very messy, with spawn and substrate debris accumulating on the floor. Since the spawning room is only used directly after each run through the pasteurization chamber, it can serve more than one purpose during non-spawning days. The spawning room should be adjacent to the main corridor leading to the growing rooms to facilitate substrate handling.

Close-up of air supply system for growing rooms featured. Air enters from below, passing through a coarse and an electrostatic air filter. A large squirrel cage blower pushes air into main duct system where two “rain trees” allow the introduction of cold or hot water into the airstream. In-house thermostats coupled to solenoid valves regulate the cold or hot (steam) water supply. Recirculation chutes enter the plenum from the side. The degree of recirculation can be controlled within the growing rooms. Preconditioning the air quality to 70–80% of desired levels is recommended before entry into the growing rooms. Provisions for excess condensation must be engineered into system.

Environment 3: The Pasteurization Chamber or Phase II Room

Purpose: To pasteurize bulk materials (straw, bagasse, etc.) by subjecting the substrate to steam for a prolonged period of time (2 to 24 hours)

Facility: Usually rectangular, the pasteurization chamber is a highly insulated room with a false floor, usually screened or grated, under which steam is injected. Two drains are recommended per pasteurization box. The drains should have a screened basket over them to prevent clogging. Ideally the drain line should have a check or gate valve to prevent contaminants being drawn into the pasteurization box during cooldown. The walls and floors must be constructed in such a manner to withstand radically fluctuating temperatures and humidities. Rooms are often constructed of cinder block, cement formed, or temperature-tolerant fiberglass-reinforced plastic (FRP). Wood construction is strongly discouraged. The pasteurization chamber should have ample head space. Large farms use “walking floors” or a net pulled by a winch, facilitating off-loading. (See illustration.)

Maximum Temperature: 210°F (99–100°C)

Minimum Temperature: Ambient

Humidity: 10–100%

Light: Minimal or none

Insulation: R30+

Positive Pressurization: Yes, through HEPA filters

Additional Comments: Pasteurization tunnels take lot of abuse from the loading and unloading of substrate. The screened floors should be removable so waste debris can be gathered after each run. Once emptied, the rooms should be doused with a bleach solution to limit the growth of any mold colonies. I have seen pasteurization tunnels made from reconverted old saunas, silage vessels, grain silos, semi-trucks, ocean cargo containers, beer fermentation vats, etc. Any doors or openings must be tightly gasketed. Provisions for the ease of filling and unloading aid production efficiency.

Environment 4: The Main Corridor—a Highway for Substrate and Product Flow

Purpose: A central hallway connecting the essential environments to one another, facilitating movement of materials, products, and personnel

Facility: Often, a metal-framed, open-truss building, is centrally located, broadside to the growing rooms. Ceilings should be at least 12 feet, ideally 20 feet high. Here again, wood surfaces should be minimized. Floors should be cement with drains and have access to waterlines for maintenance and cleanup.

Maximum Temperature: Ambient

Minimum Temperature: Ambient

Humidity: Ambient: 20–80%

Light: Skylights or moisture-proof fluorescents

Insulation: None needed

Positive Pressurization: Not needed

Additional Comments: Since this is a high-traffic area, two-way passing is essential. Those using forklifts must have ample turnaround space for maximum mobility. Many cultivators have charts and/or remote temperature sensors constructed into the walls by each growing room. Bug traps are placed at several locations to intercept winged intruders before possible entry into the mushroom growing rooms.

Environment 5: Sorting, Grading, and Packing Room

Purpose: To sort, grade, and package mushrooms into their end-user containers

Facility: A well-lit room with gravity conveyors, sorting tables, and often a blast-chiller that quickly cools the mushrooms prior to packaging and storage in the refrigeration room. This room is usually located at the end of the main corridor and is immediately adjacent to the refrigeration and shipping rooms.

Maximum Temperature: 50°F (10°C)

Minimum Temperature: 35°F (1–2°C)

Humidity: 50–75%

Light: 500–1,000 lux

Insulation: R30

Positive Pressurization: No

Additional Comments: I have seen a number of configurations of this type of processing room. Mushrooms usually arrive in open-grate plastic carrier baskets. The baskets are placed into the airstream from the blast-chiller (or in the cold room) prior to sorting into cardboard end-user boxes. Although this room is kept cool, the packaging personnel are comfortable at this temperature, busily sorting, weighing, labeling, and arranging boxes for distribution.

Environment 6: The Refrigeration Room

Purpose: To chill mushrooms to 35°F (1–2°C) so they can be maximally preserved

Facility: A standard refrigeration room

Maximum Temperature: 38°F (3°C)

Minimum Temperature: 32°F (0°C)

Humidity: 60–80%

Light: Only as needed for personnel

Insulation: R30–R60

Positive Pressurization: No

Additional Comments: Installers should engineer systems with mushroom preservation in mind, paying particular attention to humidity concerns. Standard refrigeration systems usually suffice, except that humidity must be kept between 60 and 85% RH to prevent sudden dehydration of the product. Humidity in excess of 90% often causes mushrooms to “re-vegetate,” causing a grayish fuzz and accelerating spoilage. As of 1995, Freon has been banned as a refrigerant and nonozone-destroying substitutes will be used. New refrigeration systems, including nonmechanical, carbon dioxide-based designs, are being developed. I have no information concerning their applicability to chilling and preserving mushrooms. Sufficient airflow is essential to effect slow evaporation off the cap surfaces. Still-air refrigeration systems cause mushrooms to quickly rot unless the evaporation rate is increased to compensate.

Environment 7: Shipping and Receiving Room

Purpose: To transfer mushrooms from the cold storage to the shipping/receiving area. Many farms have loading docks at the same elevation as the beds of the produce trucks picking up and delivering the product. Most facilities are equipped with overhanging doors.

Facility: An open, high-ceiling room with direct access to the main corridor, the sorting room, and/or the refrigeration room

Maximum Temperature: Ambient

Minimum Temperature: Ambient

Humidity: Ambient

Light: As needed for personnel. Fluorescents do have lenses.

Insulation: Minimal

Positive Pressurization: None

Additional Comments: A high-traffic area, the shipping and receiving room, besides its obvious purposes, is also used as a buffer, limiting the impact of environmental fluctuations from the outside. Mushrooms are usually weighed and then 10% is added to offset weight loss due to evaporation during shipment.

Environment 8: Production/Recapture Open-Air Growing Room

Purpose: To recapture as many mushrooms possible which cannot be realized in controlled-environment growing rooms. This building can solve a dilemma constantly confronting the growing room personnel: to maximize mushroom yield while not jeopardizing future crops as contaminants become more common with the cycle coming to completion.

By the third or fourth flush, yields are in a state of precipitous decline. Rather than discarding this mycelium, the cultivator can realize additional harvests, with minimum effort, if the substrate is placed outside during conducive weather conditions. In the temperate regions of the world, these favorable weather conditions span several months. During these moist months, Oyster and Shiitake mushrooms produce prolifically outdoors. I am continually amazed at the size of mushrooms that can be harvested outside from “spent” straw or sawdust that has been exported from the indoor growing rooms. Two types of buildings serve this purpose well.

Facilities: Either a hoop-frame structure covered with “bug-out” or shade cloth or a covered building with walls constructed of the same, draping from the outer roof joists

Maximum Temperature: Ambient

Minimum Temperature: Ambient

Humidity: Ambient, augmented to 85–100% by overhead sprinklers

Light: Ambient. Indirect natural light coming from the sides is best

Insulation: None needed

Positive Pressurization: n/a

Additional Comments: Two structures meet these needs well. The first is the simplest. By constructing a hoop-type greenhouse and covering it with 70–80% shade or “bug-out” cloth, moisture can penetrate through to interior and airflow is naturally high. If the pore spacing is fine enough, as in the commercially available antibug screens (“bug-out”), then flies will be hindered from entry. If a metal-roofed, open-sided haybarn is used, then draping this fabric from the outer frame to create fabric walls will accomplish a similar function. In either environment, a simple overhead misting system, activated by a timer or hand controls, will promote additional mushroom crops. Compared to the details needed for the controlled environment, high-efficiency growing rooms, the construction of these types of rooms is self-explanatory and open to modification.

Mushroom cultivation is affected as much by psychological attitude as it is by scientific method. The synergistic relationship between the cultivator and his/her cultures becomes the overwhelming governing factor in determining laboratory integrity. Since contamination is often not evident for days, even weeks, after the mistake in technique has occurred, the cultivator must develop a super-sensitive, prescient awareness. Practically speaking, this means that every time I enter the laboratory, I do so with a precautionary state of mind.

The laboratory is designed and built for the benefit of the mushroom mycelium. The role of the cultivator is to launch the mycelium onto appropriate sterile substrates in the laboratory and then leave. The less nonessential time spent by humans in the laboratory the better, since humans are often the greatest threat to the viability of the mushroom cultures. Growing mushrooms successfully is not just a random sequence of events scattered throughout the week. One’s path through the facilities, growing rooms, and laboratory can have profound implications on the integrity of the entire operation.

The growing of mushroom mycelium in absence of competitors is in total contradiction to nature. In other words, the laboratory is an artificial environment; one designed to forestall the tide of contaminants seeking to colonize the same nutritious media that has been set out for the mushroom mycelium. This could be, and is, a frightening state of affairs for most would-be cultivators until books like The Mushroom Cultivator by Stamets and Chilton (1983) and this one offered simple techniques for making sterile culture practical for mushroom cultivators. These volumes represent, historically, a critical step in the passing of the power of sterile tissue culture to the masses at large.

Before the advent of HEPA filters¹, sterile culture work succeeded only by constantly battling legions of contaminants with toxic disinfectants, presenting real health hazards to the laboratory personnel. Now, the use of disinfectants is minimized because the air is constantly being refiltered and cleaned. Once airborne contamination is eliminated, the other vectors of contamination become much easier to control. (Please consult Chapter 10 for the six vectors of contamination.)

Most people reading this book will retrofit a bedroom or walk-in pantry in their home. Large-scale, commercial operations will require a separate building. In either case, this chapter will describe the parameters necessary for designing and building a laboratory. If you are building a laboratory and pay strict attention to the concepts outlined herein, contamination will be minimized. Like a musical instrument, the laboratory must be fine-tuned for best results. Once the lab is up and running, a sterile state of equilibrium will preside for a short time. Without proper maintenance, the lab, as we say, “crashes.” The laboratory personnel must constantly clean and stay clean while they work. In effect, the laboratory personnel become the greatest threat to the lab’s sterility. Ultimately, they must shoulder the responsibility for every failure.

The laboratory should be far removed from the growing rooms, preferably in a separate building. The air of the laboratory is always kept free of airborne particulates while the growing rooms’ air becomes saturated with mushroom spores. The growing rooms are destined to contaminate. Even the spores of mushrooms should be viewed as potential contaminants threatening the laboratory. If both the laboratory and growing rooms are housed in the same building, the incidence of contamination is much more likely. Since the activities within the laboratory and growing rooms are distinctly different, separate buildings are preferred. I know of several large mushroom farms that built their spawn laboratory amid their growing rooms. Their ability to generate pure culture spawn is constantly being jeopardized by the contaminants coming from the growing rooms. Every day, the laboratory manager faces a nightmarish barrage of contaminants.

A good flow pattern of raw materials through the laboratory and of mature cultures out of the laboratory is essential. Farms with bad flow patterns must constantly wage war against seas of contaminants. The concepts are obvious. The positioning of the growing room exhaust fans should be oriented to avoid directing a “spore stream of contaminants” into the laboratory filtration system. Furthermore, the design of a mushroom farm’s buildings should take into account prevailing wind direction, sunlight exposure, shade, the positioning of the wetting or compost slabs, the location of the bulk substrate storage, and the overall flow patterns of raw materials and finished goods.

The major problem with having a laboratory within a home is the kitchen—a primary breeding ground for contamination. Rotting fruits, foods spoiling in the refrigerator, and garbage containers represent a triple-barreled threat to the laboratory’s integrity with the air and the cultivator as carrier vectors. However, good sterile technique coupled with the use of HEPA filters can make a home laboratory quite functional for the small and midsized cultivator. Most importantly, the cultivator must have a heightened awareness of his/her path through the sources of contamination before attempting sterile tissue culture. I prefer to do my laboratory work in the mornings after showering and putting on newly washed clothes. Once the lab work is completed, the laboratory personnel can enter the packaging and growing rooms. Otherwise, these areas should be strictly off-limits. In a mushroom facility, duties must be clearly allocated to each person. If you are working alone, extra attention to detail is critical to prevent cross-contamination.

Design Criteria for a Spawn Laboratory

The design criteria for constructing a spawn laboratory are not complicated. A short description of one of my labs might help the reader understand why it works so well. My first laboratory is housed in a 1,440-square-foot building. A 15 horsepower boiler is located in its own room and generates steam for the 54-inch diameter, 10-foot-long, double-door retort. The walls and ceilings are covered with FRP (fiber reinforced plastic). The lights are covered with waterproof, dustproof lenses. Plug-ins for the remote vacuum system are handy and well used. To enter, you must pass through three doors before reaching the clean room. In the clean room, a 2-foot high by 12-foot long homemade laminar flow bench gives me ample freedom of hand movement and surface area. Fresh outside air is serially filtered and positive-pressurizes the lab from overhead through a coarse prefilter, an electrostatic filter, and finally a 24 × 24-inch HEPA filter. A return duct, recycling the room’s air should be on the floor but, I admit, is not. If the return duct is located low in the laboratory, contaminants are constantly being pushed to and skimmed off the floor. My laminar flow bench—with its massive surface area—recirculates the air in the entire room once every 1.3 minutes. This is far more than what is minimally necessary.

Here are a few key concepts in designing laboratory, whether the clean room is in the home or in its own building. If incorporated into the design of your facility, contamination vectors will be minimized. Following this list are helpful suggestions of behavior, which, in combination, will give rise to an efficient, steady-state clean room.

• Positive-pressurized laboratory. The laboratory should be continuously positive-pressurized with fresh air. The fresh, outside air is serially filtered, first through a coarse prefilter (30% efficient at 1 µ), then an electrostatic filter (95% efficient at 1µ), and finally a HEPA filter (99.99% efficient at .3 µ). Blowers must be properly sized to overcome the cumulative static pressures of all the filters. In most cases, the combined static pressure approaches 1.25 inches. (Static pressure of 1 inch is the measure of resistance represented by the movement of water 1 inch, in a 1-inch diameter pipe.) Air velocity off the face of the final filter should be at least 200 feet per minute. For a 400-square-foot clean room, 2 foot × 2 foot × 6-inch filters should be employed. The construction of the intake air system should allow easy access to the filters so they can be periodically removed, cleaned, and replaced if necessary. (See illustration.) Fresh air exchange is essential to displace the carbon dioxide and other gases being generated by the mushroom mycelium during incubation. Should carbon dioxide levels escalate, the growth of contaminants becomes more likely. Sensitive cultivators can determine the quality of the laboratory immediately upon entering with their sense of smell.
• Stand-alone laminar flow bench. A laminar flow bench constantly recirculates the air within the laboratory. The air entering the laboratory has been already filtered from the positive pressurization system described in the previous paragraphs. By having two independent systems, the life span of the filter in the laminar flow bench is greatly extended. And, the clean room becomes easy to maintain. Furthermore, I am a strong believer in creating a laboratory that is characterized by turbulent air streams, with a high rate of impact through micron filters. Turbulent, filtered air in the laboratory is far more desirable than a still air environment. The key idea: If airborne particles are introduced, they are kept airborne with turbulence. If kept airborne, particles are soon impacted into the micron filters. This reduces the stratification of contaminant populations in the laboratory, and of course, temperature variations. It is important to note that this concept is diametrically opposite to the “old-school” concept that still air in the laboratory is the ideal environment for handling pure cultures.
• Double- to triple-door entries. There should be at least two doors, preferably three doors, separating the clean room from the outside environment. Double-door entries are a standard in the industry. Doors with windows have obvious advantages in preventing accidents. Furthermore, the doors should be gasketed with dirt skirts. When the doors swing outwards as you exit the innermost clean room, the export of mature spawn or blocks is made easier. (I prefer to kick the doors open upon exiting as, often, my hands are full.) As workers travel towards the clean room, they enter rooms hygienically cleaner than the previous, and into increasingly higher pressure zones. Floor decontamination pads, otherwise known as “sticky mats,” are usually placed before each doorway to remove debris from the feet.
  
     With ultra-modern clean rooms, a double-door anteroom, called a “decontamination chamber,” utilizes the downflow of HEPA-filtered air over the worker who stands on a metal grate. The air is pushed from above and actively exhausted through the floor grate to the outside. The principle concept here is valid: The constant descension of airborne particulates improves laboratory integrity. Another variation of this concept is the replacement of the solid inner doors with downflowing air curtains. However, decontamination chambers and air curtains should be the last projects on a long list of other priorities for the financially conservative investor.
• Interior surfaces not biodegradable. Interior surfaces such as the walls, countertops, shelving, etc. should not be able to support mold growth. Wood and Sheetrock should be avoided. The floors should be painted several times or overlaid with a chemically resistant, cleanable mat. When using paint, use a nonmildewing enamel. (Caution: Do not use paint containing fungicides, particular any containing tributyl tin oxide, an extremely dangerous toxin to both humans and mushrooms.) Countertops can be made of stainless steel or a hardened laboratory-grade Formica. The shelves storing the incubating bags should be wire meshed, and not solid, so that the heat generated from incubation is dissipated. Petri dish cultures can be stored on solid shelves. (See image.)
• Walls and ceiling well insulated. Ambience of temperature is critical for maintaining a laboratory. Temperature fluctuation causes two problems. When temperatures within the lab radically change from day to night, condensation forms within the spawn containers and on the upper inside of the petri dishes. These water droplets will carry otherwise dormant contaminants down to the rich media. Bacteria particularly love condensation surfaces. When a laboratory is run at 50% relative humidity and 75°F (24°C) condensation should dissipate within 24 hours after autoclaving. The other problem caused by temperature fluctuation is that the outer walls of the laboratory, especially those made of concrete, sweat. I had one small home laboratory that grew an enormous colony of white mold on a painted, white cinder-block wall. The whole laboratory contaminated despite my best efforts. Only when I washed the wall did I find the source. If your only option is a laboratory with an outside facing cinder block wall, make sure the pores have been sealed with a thick coat of paint and permanently place an electric baseboard heating unit facing the wall to eliminate the possibility of condensation.
• Lights covered with dustproof covers. Fluorescent lights should be covered with lens coverings. Uncovered lights ionize particulates that will collect as dust layers on oppositely charged surfaces. Over time, a habitat for contaminants builds. Ionizers are similar in their effect and are greatly overrated. (See Consumer Reports, October 1992.)
• Remote vacuum cleaning system. Since constant cleaning must occur throughout the inoculation process, having the ability to quickly pick up spilled grain and sawdust greatly enhances the ease of inoculation. When inoculations are done quickly, the likelihood of airborne fall-out (primarily from the cultivator) is minimized. Brooms should never be used in the laboratory. Wet/dry remote vacuums run the risk of clogging and then breeding contaminants. Therefore, a “dry” remote vacuum system is recommended.

Good Clean Room Habits: Helpful Suggestions for Minimizing Contamination in the Laboratory

• No shoes are allowed in the laboratory. The lab is strictly a “shoes-off” environment. Disposable booties are often used over socks. No outer clothing that has been exposed to the outside air should be worn into the laboratory.
• Wear newly laundered clothes and/or a laboratory coat. Once your clothes have come into contact with contaminants, these contaminants will become airborne within the laboratory. Two primary sources of contamination are people’s pets and their car seats. Once the laboratory personnel come in contact with contamination sources, their usefulness in the laboratory has been jeopardized.
• Wash hands frequently with antibacterial soap and isopropanol. Personnel should thoroughly wash their hands before entering the laboratory and, with frequency, every half-hour during the course of inoculations. Isopropanol (“rubbing” alcohol) is used for wiping countertops and hands, and topically sterilizing tools. Other disinfectants are available from the hospital supply industry.
• Frequently mop floors with a 10% bleach solution. The lab floors should be mopped at least once a week, and directly after each major run. Two buckets are used: one for bleach and one for rinsing the dirt-ladened mop. Mop heads should be frequently replaced.
• Do not conduct inoculations when you are sick with a cold, the flu, or other contagious illnesses. I know of cases where cultivators have inadvertently cultivated Staphylococcus bacteria and reinfected themselves and others. Face masks should be worn if you have no option but to work when you are sick.
• Do not speak, exhale, or sing while conducting inoculations. Your breath is laden with bacteria that thrive in the same media designed for the mushroom mycelium. If you have a telephone in your laboratory, be aware that it often becomes a redistribution point for contamination.
• Remove trash, and contaminated and over-incubated cultures daily. I do not have wastebaskets in my laboratory, forcing me to remove trash constantly and preventing a site for contamination. Over-incubated cultures are likely to contaminate so they are best rotated out of the laboratory with frequency.
• If cloning a specimen, never bring sporulating mushrooms into the laboratory. Ideally, have a second small portable laminar flow hood specifically used for cloning. I use this same laminar flow hood as a “Micron Maid” to help keep airborne particulates at reduced levels in downstream environments. New petri dish cultures from clones should be wrapped with elastic film or tape to prevent the escape of molds, bacteria, and mites into the laboratory. If sporulating molds are visible, isolate in a still-air environment.
• Isolate cultures by placing petri dishes on “sticky mats.” I came up with this innovation when fighting mites and trying to prevent cross-contamination. Sticky mats are also known as decontamination floor pads. See image.
• Establish a daily and weekly regimen of activity. Daily and weekly calendar schedules for managing the laboratory will help give continuity to the production stream. Since so many variables affect the outcome of mushroom cultivation, try to establish as many constants as possible.
• Rotate spawn frequently. Do not let cultures and spawn over-incubate. Over-incubated Oyster cultures are especially a hazard to the lab’s integrity. After 3 to 4 weeks, Oyster mushrooms will fruit within their containers, often forcing a path through the closures. If unnoticed, mushrooms will sporulate directly in the laboratory, threatening all the other cultures.

The laboratory’s health can be measured by the collective vitality of hundreds of cultures, the lack of diseases, and the diversity of strains. Once filled to capacity with the mycelia of various species, the lab can be viewed as one thermodynamically active, biological engine. The cultivator orchestrates the development of all these individuals, striving to synchronize development, en masse, to meet the needs of the growing rooms.

Success in mushroom cultivation is tantamount to not cultivating contaminants. Confounding success is you, the caretaker cultivator, resplendent with legions of microflora. Individuals vary substantially in their microbial fall-out. Smokers, pet owners, and even some persons are endemically more contaminated than others. Once contamination is released into the laboratory, spores soon find suitable niches, from which a hundredfold more contaminants will spring forth at the earliest opportunity. As this cycle starts, all means must be enacted to prevent outright mayhem. Contamination outbreaks resemble dominoes falling, and are soon overwhelming to all but the best prepared. The only recourse is the mandatory shutting down of the entire laboratory—the removal of all incubating cultures and the necessary return to stock cultures. After purging the lab of virtually everything, a strong solution of bleach is used for repetitive cleaning in short sequence. Three days in row of repetitive cleaning is usually sufficient. Clearly, prevention is a far better policy than dealing with contaminants after the fact.

No matter how well the laboratory is designed, the cultivator and his/her helpers ultimately hold the key to success or failure. Each individual can differ substantially in their potential threat to a clean room. Here’s a poignant example. At one time when contamination was on an upward spiral, I had eliminated all the vectors of contamination except one: the MCUs, mobile contamination units—which includes people and other mobile organisms. Determined to track down the source, I brought in an expensive airborne particulate meter, used commonly by the computer industry to judge the quality of clean rooms. This unit measured airborne contamination per cubic meter through a range of particle sizes, from .10 microns to >10 microns.

Several fascinating results were observed. One obvious measurement was that, in a calm air room, 100 times more particulates were within 1 foot of the floor than were within a foot of the ceiling. Truly, the air exists as an invisible sea of contaminants. What was most surprising was the contamination fall-out from each employee. Standing each employee in the airstream coming from the laminar flow bench, I recorded downwind particle counts. The contamination source was immediately identified. An employee was generating nearly 20 times the contamination fall-out than anyone else. The dirty employee was summarily banned from the laboratory. Soon thereafter, the integrity of the laboratory was restored. The lesson learned—that humans carry their own universe of contaminants—and are the greatest threat to clean room integrity.

The first attempts at growing mushrooms indoors were in caves in France late in the eighteenth century. They provided an ideal environment for the Button mushroom (probably Agaricus brunnescens): constant, cool temperature and high humidity. To this day, cave culture for the Button mushroom is still widely practiced. One of the largest mushroom farms in the world utilizes an extensive network of caves in Butler County, Pennsylvania. Cave culture has one major drawback for gourmet mushroom production: darkness.

The Button mushroom does not require nor is sensitive to light. All the other mushrooms described in this book are phototropic. This major difference—the need for light—presents a financial obstacle to the retrofitting of Button mushroom farms into gourmet mushroom production facilities. Many gourmet mushroom farms must build customized growing rooms. But, in many cases, other types of structures can be retrofitted for commercial production. Here are some examples:

In general, custom-designed growing rooms will perform better than structures that have been engineered for other purposes. However, with wise modifications, any of the above structures can be made into intensive growing chambers.

Caves were used as growing chambers in France circa 1868. (Reprinted from Robinson’s Mushroom Culture, 1885.)

Whereas the laboratory is maintained at a constant temperature and humidity, the growing room’s environment is fluctuated during the development of the mushroom crop. These changes in environment are specific, and sometimes must be radical, to trigger the switchover to mushroom formation and development. Whole new sets of skills are demanded of the growing room manager, which are distinctly not needed by the laboratory technician. The ability of the manager to implement these changes is directly affected by the design of the growing rooms. Here are some of the design criteria that must be satisfied for creating a functioning growing room.

The first growing rooms resembled chicken houses. Reprinted from a 1929 USDA circular: The Mushroom Growing House.

Design Criteria for the Growing Rooms

Shape. The general shape of a growing room should be rectangular. I have never seen a square or circular growing room function well. The growing room should be at least twice as long as it is wide. This configuration allows for air to be distributed down a central ductwork. The rectangular shape is naturally process oriented: permitting the flow-through of substrate materials and fresh mushrooms. Rectangular rooms are simply easier to manage.

Interior walls. The inside skin of a growing room must be built of water- and mold-resistant materials. Fiberglass, polycarbonate, acrylic, glass, and galvanized metals can be used for the interior of a growing room. The material of choice, by most professional cultivators, is called FRP (for fiberglass reinforced plastic). This high-temperature-extruded fiberglass material has a smoothed finish, and its pliability makes installation simple. Furthermore, FRP will not be degraded by mold fungi, does not out-gas toxic fumes, and is tolerant to most cleaning agents. Wood or metal surfaces can be painted with a mold-/rust-resistant glazing. Cultivators should check with local ordinances so that the materials used in their growing rooms fully comply with food production and building code standards.

For those with limited budgets, the cheapest material is polyethylene plastic sheeting used by the greenhouse industry. This material usually survives no more than 2 or 3 years under the conditions used for growing mushrooms. I have attached greenhouse sheeting using galvanized staples over lengths of thick plastic tape.

Doors. As with the laboratory, the growing rooms should be protected from the outside by at least two doors. The first door from the outside leads into an operations room or hallway where the second door opens into the growing room. Doors should be at least 4 × 8 feet. Some farms have two 5 × 10-foot double-opening bay doors, or a 10 × 10-foot sliding door. These large doors allow the easy filling and emptying of the growing rooms. A small door is sometimes inner-framed within one of the larger doors so the growing room environment is not jeopardized when only personnel need to enter. In any event, the doors should accommodate small forklifts or similar machinery that need access to the growing rooms. The doors should be made of a material that does not support the growth of molds. The bottom of the door is often fitted with a brush-skirt that discourages insects from entering. The doorjambs are usually gasketed to assure a tight seal when closed.

At the opposite end of the growing room, a similarly sized exit door should be installed. This door facilitates the emptying of the growing room after the cropping cycle has been completed. To bring aged substrate, which is often contaminated after the fourth or fifth flush, into the same corridor that leads to other growing rooms presents a significant cross-contamination vector.

Modified gothic-framed buildings have several advantages. Simple and quick to build, these buildings have walls with an inside curvature that keeps condensation from dripping onto the crop. The condensation adheres to the walls and streams to the floor where it is re-evaporated or drained off. The peak roof allows for the removal of excess heat and/or the mixing of humidity and air prior to contact with the mushroom crop.

Many farms employ pass-through curtains, usually made of clear, thick, overlapping strips of plastic. These are especially useful in the sorting, packaging, and refrigeration rooms. However, pass-through curtains do not afford a tight enough seal for protection of the growing rooms from other environments.

Structures insulated. Environmental control systems will function far better in growing rooms that are insulated than in those that are not. Some strains of mushrooms are far more sensitive to temperature fluctuation than others. In localities where temperature fluctuation is extreme, insulation is essential. Some cultivators partially earth-berm portions of their growing rooms for this purpose. When using insulation, make sure it is water-repellent and will not become a food source for molds.

Inside roof. The inside roof should be curved or peaked for heat redistribution by the air circulation system. Furthermore, the slope of the inside roof should be angled so that condensation adheres to the sloped roof surface and is carried to the walls, and eventually spills onto the floor. This allows for the re-evaporation from the floor back into air. The height of a growing room should be at least 10 feet, preferably 12–16. At least 4–6 feet of free air space should be above the uppermost plateau of mushrooms.

Flat roofs encourage condensation, and a microclimate for contamination growth. If the cultivator has no choice but to work with a flat roof, I recommend the installment of lengths of 6- to 12-inch diameter drain-field pipe, perforated every 2 feet with 1-inch holes, down the length of each growing room at the junction of the wall and the ceiling. By installing a “T” midspan, and locating a downward flowing duct fan at the base of the “T,” you can draw air into the holes. This scheme will eliminate the dead-air pockets that form along the corner of the wall and ceiling. With fine-tuning, entrainment of the air can be greatly improved. (Entrainment can be measured by a “smoke or steam” test, observing the swirling air patterns.)

Floors. Floors should be cement, painted with a USDA-approved, dairy-grade cement, and sloped to a central drain. Channel-like drains used in dairies work well, although they need not be wider than 6 inches. Before the entrance to the drain-field, a screened basket fashioned out of metal mesh prevents clogging. This basket should be easily removed for daily cleaning. Once every several days, a cup of bleach is washed into the drain to discourage flies from breeding.

A Texas Reishi production facility. With modified hoop-framed greenhouses covered with an open-sided, metal roofed super-structure, growing rooms could be constructed at low cost.

Many cultivators install a footbath prior to each growing room to disinfect footwear. (Shoes are a major vector of contamination of soil-borne diseases into the growing rooms.) These footbaths are built into the cement slab before pouring so that a drain can be installed. A 2 foot × 3 foot × 2-inch recessed footbath is ideal. The drain is capped and filled water. Bleach (chlorine) is added as a disinfectant. A plastic, metal, or sponge-like grate helps remove debris from the feet and enhances the effectiveness of the footbath.

Rate of air exchange. Air exchanges control the availability of fresh oxygen and the purging of carbon dioxide from the respiring mushroom mycelium. High air exchange rates may adversely affect humidity, especially prior to and at primordia formation when aerial mycelium abounds. Should aerial mycelial die back, or “pan,” potential yields are substantially depressed. On the other hand, to prevent malformation of the fruitbody, bacterial blotch, and mold infestation, the movement of air—turbidity—is a substantial factor in preventing disease vectors.

An insulated growing room constructed on the interior and exterior with weatherproof metal siding.

The need for adequate air exchange is a direct reflection of the species being grown, its rate of metabolism (as measured by CO₂ generation), and the “density of fill.” Fast-growing, tropical strains generate more CO₂ than cold-weather strains due to their higher rate of metabolism. The density of fill is the fraction of space occupied by substrate versus the total volume of the growing room. Button mushrooms growers often fill up to ¼ of the growing room space with substrate. This high rate of fill is impractical with most gourmet mushrooms. I recommend filling the growing rooms to no more than ⅙th, and preferably ⅛th, of capacity.

At 1,000 cubic feet per minute (cfm) of free air delivery, the air in an empty 10,000-cubic-foot room will be exchanged every 10 minutes, equivalent to 6 air exchanges per hour. This rate of air exchange is near the minimum required for gourmet mushroom cultivation. At 2,000 cfm, this same room will be exchanged every 5 minutes, or 12 air exchanges per hour. Another way to calculate the needed CFM is to assume 2 CFM/square foot in each growing room. I recommend designing growing rooms that can operate within this rate of air exchange, i.e., between 6 and 12 air exchanges per hour. The actual rate of air exchange will be lower, affected by the rate of fill and limited by the avenues of exhaust. The growing rooms should always remain positive-pressurized to limit contamination vectors from the outside. A strip of cloth or plastic above the doorjamb works well as a simple visual indicator of positive pressurization.

A 400–600 cfm thermal exhaust fan is recommended for a growing room of the above-described dimensions. This fan is typically located at the apex of the growing room, opposite the incoming air. A thermostat, preset by the cultivator to skim off excess heat, activates this fan. Another fan, which I call a “vortex fan” having a 200–400 cfm capacity, is located below the thermal exhaust fan, usually at head level, above the exit door. The vortex fan helps enhance the cyclonic entrainment of the air as it moves down the growing room. Both fans should be covered, from the inside, with a bugproof, nonmildewing cloth. This cloth will prevent the entry of insects when the fans are not in operation. Furthermore, the thermal exhaust and vortex fan should have louver shutters that close when not in use.

This is but one configuration of a growing room. Ideally, the growing room environment rotates as a giant wind tunnel, providing a homogeneously mixed atmosphere. Simplicity of design makes operation easy. Each growing room should be independently controlled so crops can be cycled and managed according to their stage of development.

Filtration of fresh air supply. Fresh air is brought in from the outside and passed through a series of filters. The growing rooms do not require the degree of filtration that is necessary for the laboratory. Since the growing room will, at times, have full air exchanges of 4 to 10 times per hour, the filters must have sufficient carrying capacity. Air is first filtered through a standard Class 2 prefilter. These filters are relatively coarse, filtering particles down to 10 microns with 30% efficiency. Prefilters are disposable and should be replaced regularly, in most cases every 1 to 3 months. The next filter is usually electrostatic. Electrostatic filters vary substantially in their operating capacities and airflow parameters. Typically, particulates are filtered down to 1 micron with 95% efficiency. Electrostatic filters can be removed, periodically, for cleaning with a soapy solution. Their performance declines as dust load increases. For most growing rooms of 10,000–20,000 cubic feet, a 25 × 20 × 6-inch electrostatic filter suffices when combined with a fan sending 1,000–2,000 cubic feet per minute airstream into each growing room.

Filtration of recirculated air. Recirculated air from a growing room is relatively free of airborne particulates during the colonization phase. When the cropping cycle begins, the air becomes thick with mushroom spores. (This is especially the case with Oyster mushrooms and much less so with Button mushroom cultivation.) I have seen the spore load of Oyster mushrooms become so thick as to literally stop the rotation of high-volume cfm fans!

The design of an air system should allow partial to full recirculation of the air within the growing room. Usually, a recirculation duct is centrally located directly below the incoming air. A damper door controls the degree of recirculation. If the recirculated air is passed through filters, these filters will quickly clog with mushroom spores, and airflow will radically decline. If electing to use filters, they should be changed every day during the cropping cycle. A simple way of cleaning the recirculated air is to position mist nozzles in the recirculation ductwork. The air will be largely rinsed clean of their spore load from the spray of water. Ideally, these downward flowing nozzles are located directly above a drain. Having spray nozzles located below the inside roofline and misting downwards will also facilitate the downward flow of spores to the floor. This concept can have many permutations.

Humidification. With the 6 to 12 air exchanges per hour required during the primordia formation period, full humidification within the growing room is difficult if drawing in dry outside air. This problem is solved through the conditioning of outside air in an intermediate chamber called a preconditioning plenum. The preconditioning plenum is usually located outside of the growing room. Its purpose to elevate humidity and alter temperature to levels adjustable by the in-room environmental systems. One preconditioning plenum can supply several growing rooms, if properly designed.

In cold climates or during the cold winter months, the preconditioning plenum can be largely humidified with steam. Steam provides both moisture and heat. Thermostats located in the preconditioning plenum and/or growing room activate solenoid valves on live steam lines coming from an on-duty boiler. Steam is sent downstream to a square-shaped grid of interconnected pipes. Holes have been drilled to orient the flow of steam towards the center. The main air system blower pushes the steam from the preconditioning box into the growing rooms. Each growing room has its own high-volume axial fan that inflates the ducting and distributes the humidified and heated air. Since moisture will collect in the polyethylene ducting, provisions must be made for removing this condensate. The simplest solution is to slant the duct at a slight angle. The condensation can then drip directly into the channel drain running lengthwise down the center of the room.

When the temperature in the growing room exceeds prescribed levels, the thermostat will close the in-line solenoid valve. Humidity will fall. A humidistat sensing the humidity in the preconditioning plenum takes control, opening a separate solenoid valve, sending cold water downline, activating the mist nozzles. The cold water lines should be positioned in a fashion so that they are not damaged when the steam lines are in operation. The goal here is to elevate humidity to 75–80% RH. Independent humidifiers or mist nozzles located high in the growing rooms control the remaining 25% of the humidity required for primordia formation. Some companies offer systems that utilize compressed-air (100 to 400 psi) misting systems that emanate a fog-like cloud of humidity. With proper filtration and maintenance these systems work equally as well although typically are much more expensive to install.

Swamp coolers generate humidity and lower temperature of the incoming air. They work especially well when the outside air temperature is high and the humidity is low. These types of evaporative coolers can also be incorporated into the design of a preconditioning box. Heat exchangers must be carefully engineered for maximum effect. The cultivator is encouraged to consult a reputable HVAC (heating, ventilation, and air conditioning) specialist before installation of any of the above-mentioned systems. Often, independent systems with manual control overrides perform better, in the long run, than all-in-one packages. The cultivator must have alternatives for humidity should equipment fail for any reason. The value of one saved crop can easily offset the expense of a simple backup system.

Insect control. Flies are the bane of the mushroom cultivator. Once introduced, a single pregnant fly can give rise to hundreds of voracious offspring in a few weeks. (For a complete description of the flies and their life cycles, please consult The Mushroom Cultivator, 1983, by Stamets and Chilton.) Many models of insect traps are available. “Bug zappers” electrocute flies when they come in between two opposite-charged metal screens. Many of the flies endemic to mushroom culture are minute and pass, unaffected, between the electrified panels. I prefer circular bug lights that use an interior fan. A cone-shaped vortex is formed well beyond the light. The bugs are thrown into a plastic bag that allows for easy counting by the growing room manager. By attaching yellow sticky pads to the lights, the number of flies that can be caught greatly increases. Astute managers rely on the increasing numbers of flies as an indication of impending disaster. These lights should be positioned on or beside every door within the growing room, and especially in the rooms prior to the growing rooms. Many of the fly problems can be circumvented through some of the good practices described below.

Managing the Growing Rooms: Good Habits for the Personnel

Integral to the success of a mushroom farm is the daily management of the growing rooms. The environment within the growing room is constantly in a dynamic state of change. Events can quickly cascade, drastically, and sometimes inalterably, affecting the outcome of the crop. The daily activities of the personnel especially impact the quality of the crop. The head cultivator can perfectly execute his or her duties only to have employees unwittingly sabotage the crop. In many cases, a simple redirection of the sequence of activities can correct the problem. With consistently followed well-defined rules of conduct, the growing rooms can function to their fullest potential. I recommend establishing a daily and weekly schedule that defines the activities of the personnel. By following a calendar, the crew becomes self-organizing according to the days of the week.

Maintain personal hygiene. Shower every day. Wear newly laundered clothes. Avoid contact with molds, soils, pets, etc. Body odors are a result of growing colonies of bacteria. Those with poor personal hygiene threaten the stability of a farm. If employees cannot maintain good personal hygiene, then they must be fired.

Keep the property clean. Particular emphasis should be on removing any organic debris that accumulates directly after a production run or harvest. All excess materials should be placed in a specifically allocated, dry storage location. Waste materials should be composted a safe distance away from the production facility.

Isolate or minimize contact between growing room managers, pickers, and other workers. Growing room managers present the same problem doctors do in hospitals: They spread disease. All personnel should wash their hands several times a day and/or wear gloves. The growing room manager should point out contamination for workers to remove. The growing room manager, unless alone, should not handle contaminants. Furthermore, laboratory personnel and growing room personnel should not share the same lunchroom, a common site for the redistribution of contaminants.

Use footbaths. Step in disinfectant footbaths prior to going into each growing room. Change baths daily.

Frequently wash down growing rooms. The activity most affecting the maintenance of a growing room is its thorough washing down once in the morning and once in the evening. After spraying the ceilings, walls, and floors with water (untreated), direct any debris to the central drain channel, and collect and remove it. After a washing, the room takes on a freshness that is immediately apparent. The growing room feels fresh.

Record maximum/minimum/ambient temperature at the same time each day. Temperature profiling at different elevations is deemed necessary only in poorly insulated rooms. With turbulent air circulation, in a highly insulated environment, temperature stratification is minimized. Manual temperature readings should occur at the same time every day. If constant-duty chart recorders or computer sensing systems are in place, they should be reviewed daily and compared. Ambience of temperature within 3–5°F (2–3°C) is preferred.

Chart relative humidity. Relative humidity requirements change with each species, each day. Charting humidity can be a valuable tool in training the growing room manager to delicately balance the environment in favor of mushroom formation and development, but limiting the growth of molds. Wood-based substrates are particularly susceptible to green mold growth if humidity is too high directly after removal of the blocks from the soaking tank. For instance, Shiitake blocks benefit from a fluctuating humidity environment whereas Oyster mushrooms require sustained 90%+ humidity.

Dispose of contamination once a day. Once you have handled contamination, consider yourself contaminated. If removing Trichoderma (green mold) contaminated blocks of Shiitake, that person is then unworthy of any activity where susceptible substrates are handled. For many growers, this mandates that contaminated cultures be disposed at the end of the day. If contamination must be dealt with early in the workday, a person nonessential to the production stream should be the designated disposer of contaminated cultures.

The following resource directory is not an endorsement of any organization, company, individual, or author. The sole intent is to give the reader the broadest range of resources so that mushrooms can be grown successfully. An omission of any group is probably not intentional. If you know of any resource that should be listed, feel free to write to the author so that future editions of Growing Gourmet and Medicinal Mushrooms will include them.

Recommended Mushroom Field Guides

Cultivators must constantly return to nature for new strains. If mushrooms are not properly identified, the cultures will be inaccurately labeled. Once these cultures are passed on to other individuals, the misidentification may not be discovered for years, if ever. An excellent example of this is what happened with cultures of “Pleurotus sajor-caju,” most of which are in fact P. pulmonarius. (See the discussion of the taxonomy of P. pulmonarius here.) Cultivators are encouraged to photograph the wild mushroom in fresh condition, retain a dried specimen, and make notes about its location and habitat. Without this data, accurately identifying the mushroom (and therefore the culture) will be difficult.

The following field guides are designed primarily to help amateurs in the field. Professional mycologists (although some are loathe to admit it) refer to these manuals also, particularly when they need a quick overview of the species complexes. Scientific monographs are ultimately used for confirming the identity of a mushroom to species. Amateurs should be fully aware that even professional mycologists make mistakes.

Mushroom Book Suppliers

Annual Mushroom Festivals and Events

Many of the mycological societies stage annual mushroom exhibits. Here is a short list of some of the more notable annual mushroom exhibitions. Most are held in September or October unless otherwise indicated. Please contact them for more specific information.

Mushroom Cultivation Seminars and Training Centers

Mushroom Study Tours and Adventures

International Mushroom Associations

North American Mushroom Societies and Associations

Mushroom Growers Associations in the United States

Many of the previously listed mycological societies have established “Cultivation Committees,” which organize members interested in mushroom cultivation. The following organizations are independent of any mycological society.

Sources for Mushroom Cultures

Sources for Mushroom Spawn

International Mushroom Growers Associations and Sources for Marketing Information

Mushroom Newsletters and Journals

Mushroom Museums

Sources for Medicinal Mushroom Products

Mycological Resources on Internet

DRY ROUGHAGES OF FIBROUS MATERIALS

Material : Alfalfa hay, all analyses

Total dry matter per ct. : 90.5

Protein per ct. : 14.8

Fat per ct. : 2.0

Fiber per ct. : 28.9

N-free extract per ct. : 36.6

Total minerals per ct. : 8.2

Calcium per ct. : 1.47

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.37

Potassium per ct. : 2.05

Material : Alfalfa hay, very leafy (less than 25% fiber)

Total dry matter per ct. : 90.5

Protein per ct. : 17.2

Fat per ct. : 2.6

Fiber per ct. : 22.6

N-free extract per ct. : 39.4

Total minerals per ct. : 8.7

Calcium per ct. : 1.73

Phosphorus per ct. : 0.25

Nitrogen per ct. : 2.75

Potassium per ct. : 2.01

Material : Alfalfa hay, leafy (25-28% fiber)

Total dry matter per ct. : 90.5

Protein per ct. : 15.8

Fat per ct. : 2.2

Fiber per ct. : 27.4

N-free extract per ct. : 36.6

Total minerals per ct. : 8.5

Calcium per ct. : 1.50

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.53

Potassium per ct. : 2.01

Material : Alfalfa hay, stemmy (over 34% fiber)

Total dry matter per ct. : 90.5

Protein per ct. : 12.1

Fat per ct. : 1.4

Fiber per ct. : 36.0

N-free extract per ct. : 33.4

Total minerals per ct. : 7.6

Calcium per ct. : 1.10

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.94

Potassium per ct. : 1.68

Material : Alfalfa hay, before bloom

Total dry matter per ct. : 90.5

Protein per ct. : 19.0

Fat per ct. : 2.7

Fiber per ct. : 22.6

N-free extract per ct. : 36.7

Total minerals per ct. : 9.5

Calcium per ct. : 2.22

Phosphorus per ct. : 0.33

Nitrogen per ct. : 3.04

Potassium per ct. : 2.14

Material : Alfalfa hay, past bloom

Total dry matter per ct. : 90.5

Protein per ct. : 12.8

Fat per ct. : 2.1

Fiber per ct. : 31.9

N-free extract per ct. : 36.2

Total minerals per ct. : 7.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.05

Potassium per ct. : —

Material : Alfalfa hay, brown

Total dry matter per ct. : 87.9

Protein per ct. : 17.3

Fat per ct. : 1.6

Fiber per ct. : 24.5

N-free extract per ct. : 35.1

Total minerals per ct. : 9.4

Calcium per ct. : 1.37

Phosphorus per ct. : 0.26

Nitrogen per ct. : 2.77

Potassium per ct. : —

Material : Alfalfa hay, black

Total dry matter per ct. : 83.1

Protein per ct. : 17.5

Fat per ct. : 1.5

Fiber per ct. : 29.1

N-free extract per ct. : 25.3

Total minerals per ct. : 9.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.80

Potassium per ct. : —

Material : Alfalfa leaf meal

Total dry matter per ct. : 92.3

Protein per ct. : 21.2

Fat per ct. : 2.8

Fiber per ct. : 16.6

N-free extract per ct. : 39.7

Total minerals per ct. : 12.0

Calcium per ct. : 1.69

Phosphorus per ct. : 0.25

Nitrogen per ct. : 3.39

Potassium per ct. : —

Material : Alfalfa leaves

Total dry matter per ct. : 90.5

Protein per ct. : 22.3

Fat per ct. : 3.0

Fiber per ct. : 14.2

N-free extract per ct. : 40.5

Total minerals per ct. : 10.5

Calcium per ct. : 2.22

Phosphorus per ct. : 0.24

Nitrogen per ct. : 3.57

Potassium per ct. : 2.06

Material : Alfalfa meal

Total dry matter per ct. : 92.7

Protein per ct. : 16.1

Fat per ct. : 2.2

Fiber per ct. : 27.1

N-free extract per ct. : 38.2

Total minerals per ct. : 9.1

Calcium per ct. : 1.32

Phosphorus per ct. : 0.19

Nitrogen per ct. : 2.58

Potassium per ct. : 1.91

Material : Alfalfa stem meal

Total dry matter per ct. : 91.0

Protein per ct. : 11.5

Fat per ct. : 1.3

Fiber per ct. : 36.3

N-free extract per ct. : 34.8

Total minerals per ct. : 7.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.84

Potassium per ct. : —

Material : Alfalfa straw

Total dry matter per ct. : 92.6

Protein per ct. : 8.8

Fat per ct. : 1.5

Fiber per ct. : 40.4

N-free extract per ct. : 35.1

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : 0.13

Nitrogen per ct. : 1.41

Potassium per ct. : —

Material : Alfalfa and bromegrass hay

Total dry matter per ct. : 89.3

Protein per ct. : 12.4

Fat per ct. : 2.0

Fiber per ct. : 28.6

N-free extract per ct. : 38.1

Total minerals per ct. : 8.2

Calcium per ct. : 0.74

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.98

Potassium per ct. : 2.18

Material : Alfalfa and timothy hay

Total dry matter per ct. : 89.8

Protein per ct. : 11.1

Fat per ct. : 2.2

Fiber per ct. : 29.5

N-free extract per ct. : 40.3

Total minerals per ct. : 6.7

Calcium per ct. : 0.81

Phosphorus per ct. : 0.21

Nitrogen per ct. : 1.78

Potassium per ct. : 1.78

Material : Alfilaria, dry (Erodium cicutarium)

Total dry matter per ct. : 89.2

Protein per ct. : 10.9

Fat per ct. : 2.9

Fiber per ct. : 23.4

N-free extract per ct. : 40.2

Total minerals per ct. : 11.8

Calcium per ct. : 1.57

Phosphorus per ct. : 0.41

Nitrogen per ct. : 1.74

Potassium per ct. : —

Material : Alfilaria, dry, mature

Total dry matter per ct. : 89.0

Protein per ct. : 3.5

Fat per ct. : 1.5

Fiber per ct. : 31.4

N-free extract per ct. : 44.1

Total minerals per ct. : 8.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.56

Potassium per ct. : —

Material : Atlas sorghum stover

Total dry matter per ct. : 85.0

Protein per ct. : 4.0

Fat per ct. : 2.0

Fiber per ct. : 27.9

N-free extract per ct. : 44.2

Total minerals per ct. : 6.9

Calcium per ct. : 0.34

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.64

Potassium per ct. : —

Material : Barley hay

Total dry matter per ct. : 90.8

Protein per ct. : 7.3

Fat per ct. : 2.0

Fiber per ct. : 25.4

N-free extract per ct. : 49.3

Total minerals per ct. : 6.8

Calcium per ct. : 0.26

Phosphorus per ct. : 0.23

Nitrogen per ct. : 1.17

Potassium per ct. : 1.35

Material : Barley straw

Total dry matter per ct. : 90.0

Protein per ct. : 3.7

Fat per ct. : 1.6

Fiber per ct. : 37.7

N-free extract per ct. : 41.0

Total minerals per ct. : 6.0

Calcium per ct. : 0.32

Phosphorus per ct. : 0.11

Nitrogen per ct. : 0.59

Potassium per ct. : 1.33

Material : Bean hay, mung

Total dry matter per ct. : 90.3

Protein per ct. : 9.8

Fat per ct. : 2.2

Fiber per ct. : 24.0

N-free extract per ct. : 46.6

Total minerals per ct. : 7.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.57

Potassium per ct. : —

Material : Bean hay, tepary

Total dry matter per ct. : 90.0

Protein per ct. : 17.1

Fat per ct. : 2.9

Fiber per ct. : 24.8

N-free extract per ct. : 34.7

Total minerals per ct. : 10.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.74

Potassium per ct. : —

Material : Bean pods, field, dry

Total dry matter per ct. : 91.8

Protein per ct. : 7.1

Fat per ct. : 1.0

Fiber per ct. : 34.8

N-free extract per ct. : 45.0

Total minerals per ct. : 3.9

Calcium per ct. : 0.78

Phosphorus per ct. : 0.10

Nitrogen per ct. : 1.14

Potassium per ct. : 2.02

Material : Bean straw, field

Total dry matter per ct. : 89.1

Protein per ct. : 6.1

Fat per ct. : 1.4

Fiber per ct. : 40.1

N-free extract per ct. : 34.1

Total minerals per ct. : 7.4

Calcium per ct. : 1.67

Phosphorus per ct. : 0.13

Nitrogen per ct. : 0.98

Potassium per ct. : 1.02

Material : Beggarweed hay

Total dry matter per ct. : 90.9

Protein per ct. : 15.2

Fat per ct. : 2.3

Fiber per ct. : 28.4

N-free extract per ct. : 37.2

Total minerals per ct. : 7.8

Calcium per ct. : 1.05

Phosphorus per ct. : 0.27

Nitrogen per ct. : 2.43

Potassium per ct. : 2.32

Material : Bent grass hay, Colonial

Total dry matter per ct. : 88.5

Protein per ct. : 6.6

Fat per ct. : 3.0

Fiber per ct. : 29.5

N-free extract per ct. : 42.8

Total minerals per ct. : 6.6

Calcium per ct. : —

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.06

Potassium per ct. : 1.42

Material : Bermuda grass hay

Total dry matter per ct. : 90.6

Protein per ct. : 7.2

Fat per ct. : 1.8

Fiber per ct. : 25.9

N-free extract per ct. : 48.7

Total minerals per ct. : 7.0

Calcium per ct. : 0.37

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.15

Potassium per ct. : 1.42

Material : Bermuda grass hay, poor

Total dry matter per ct. : 90.0

Protein per ct. : 5.8

Fat per ct. : 0.9

Fiber per ct. : 38.8

N-free extract per ct. : 37.7

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Berseem hay, or Egyptian clover

Total dry matter per ct. : 91.7

Protein per ct. : 13.4

Fat per ct. : 2.7

Fiber per ct. : 21.0

N-free extract per ct. : 42.7

Total minerals per ct. : 11.9

Calcium per ct. : 3.27

Phosphorus per ct. : 0.28

Nitrogen per ct. : 2.14

Potassium per ct. : 2.05

Material : Birdsfoot trefoil hay

Total dry matter per ct. : 90.5

Protein per ct. : 13.8

Fat per ct. : 2.1

Fiber per ct. : 27.5

N-free extract per ct. : 41.2

Total minerals per ct. : 5.9

Calcium per ct. : 1.13

Phosphorus per ct. : 0.22

Nitrogen per ct. : 2.35

Potassium per ct. : 1.52

Material : Black grass hay (Juncus Gerardi)

Total dry matter per ct. : 89.7

Protein per ct. : 7.5

Fat per ct. : 2.5

Fiber per ct. : 25.1

N-free extract per ct. : 47.3

Total minerals per ct. : 7.3

Calcium per ct. : —

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.20

Potassium per ct. : 1.56

Material : Bluegrass hay, Canada

Total dry matter per ct. : 89.3

Protein per ct. : 6.6

Fat per ct. : 2.3

Fiber per ct. : 28.2

N-free extract per ct. : 46.4

Total minerals per ct. : 5.8

Calcium per ct. : —

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.06

Potassium per ct. : 1.94

Material : Bluegrass hay, Kentucky, all analyses

Total dry matter per ct. : 89.4

Protein per ct. : 8.2

Fat per ct. : 2.8

Fiber per ct. : 29.8

N-free extract per ct. : 42.1

Total minerals per ct. : 6.5

Calcium per ct. : 0.46

Phosphorus per ct. : 0.32

Nitrogen per ct. : 1.31

Potassium per ct. : 1.73

Material : Bluegrass hay, Kentucky, in seed

Total dry matter per ct. : 87.3

Protein per ct. : 5.5

Fat per ct. : 2.5

Fiber per ct. : 31.0

N-free extract per ct. : 41.9

Total minerals per ct. : 6.4

Calcium per ct. : 0.23

Phosphorus per ct. : 0.20

Nitrogen per ct. : 0.88

Potassium per ct. : 1.48

Material : Bluegrass hay, native western

Total dry matter per ct. : 91.9

Protein per ct. : 11.2

Fat per ct. : 3.0

Fiber per ct. : 29.8

N-free extract per ct. : 39.9

Total minerals per ct. : 8.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.79

Potassium per ct. : —

Material : Bluejoint hay (Calamagrostis Canadensis)

Total dry matter per ct. : 88.5

Protein per ct. : 7.2

Fat per ct. : 2.3

Fiber per ct. : 32.9

N-free extract per ct. : 39.6

Total minerals per ct. : 6.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.15

Potassium per ct. : —

Material : Bluestem hay (Andropogon, spp.)

Total dry matter per ct. : 86.6

Protein per ct. : 5.4

Fat per ct. : 2.2

Fiber per ct. : 30.2

N-free extract per ct. : 43.4

Total minerals per ct. : 5.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.86

Potassium per ct. : —

Material : Bromegrass hay, all analyses

Total dry matter per ct. : 88.1

Protein per ct. : 9.9

Fat per ct. : 2.1

Fiber per ct. : 28.4

N-free extract per ct. : 39.5

Total minerals per ct. : 8.2

Calcium per ct. : 0.20

Phosphorus per ct. : 0.28

Nitrogen per ct. : 1.58

Potassium per ct. : 2.35

Material : Bromegrass hay, before bloom

Total dry matter per ct. : 89.0

Protein per ct. : 14.5

Fat per ct. : 2.3

Fiber per ct. : 24.6

N-free extract per ct. : 37.9

Total minerals per ct. : 9.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.32

Potassium per ct. : —

Material : Broom corn stover

Total dry matter per ct. : 90.6

Protein per ct. : 3.9

Fat per ct. : 1.8

Fiber per ct. : 36.8

N-free extract per ct. : 42.4

Total minerals per ct. : 5.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.62

Potassium per ct. : —

Material : Buckwheat hulls

Total dry matter per ct. : 88.6

Protein per ct. : 3.0

Fat per ct. : 1.0

Fiber per ct. : 42.9

N-free extract per ct. : 40.1

Total minerals per ct. : 1.6

Calcium per ct. : 0.26

Phosphorus per ct. : 0.02

Nitrogen per ct. : 0.48

Potassium per ct. : 0.27

Material : Buckwheat straw

Total dry matter per ct. : 88.6

Protein per ct. : 4.3

Fat per ct. : 1.0

Fiber per ct. : 36.2

N-free extract per ct. : 38.8

Total minerals per ct. : 8.3

Calcium per ct. : 1.24

Phosphorus per ct. : 0.04

Nitrogen per ct. : 0.69

Potassium per ct. : 2.00

Material : Buffalo grass hay (Bulbil is dactyloides)

Total dry matter per ct. : 88.7

Protein per ct. : 6.8

Fat per ct. : 1.8

Fiber per ct. : 23.8

N-free extract per ct. : 46.2

Total minerals per ct. : 10.1

Calcium per ct. : 0.70

Phosphorus per ct. : 0.13

Nitrogen per ct. : 1.09

Potassium per ct. : 1.36

Material : Bunchgrass hay, misc. varieties

Total dry matter per ct. : 91.7

Protein per ct. : 5.8

Fat per ct. : 2.0

Fiber per ct. : 30.4

N-free extract per ct. : 44.1

Total minerals per ct. : 9.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Carpet grass hay

Total dry matter per ct. : 92.1

Protein per ct. : 7.0

Fat per ct. : 2.2

Fiber per ct. : 31.8

N-free extract per ct. : 40.9

Total minerals per ct. : 10.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.12

Potassium per ct. : —

Material : Cat-tail, or tule hay (Typha angustifolia)

Total dry matter per ct. : 90.8

Protein per ct. : 5.8

Fat per ct. : 1.7

Fiber per ct. : 30.8

N-free extract per ct. : 44.3

Total minerals per ct. : 8.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Cereals, young, dehydrated

Total dry matter per ct. : 92.8

Protein per ct. : 24.5

Fat per ct. : 4.7

Fiber per ct. : 16.1

N-free extract per ct. : 33.1

Total minerals per ct. : 14.4

Calcium per ct. : 0.66

Phosphorus per ct. : 0.46

Nitrogen per ct. : 3.92

Potassium per ct. : —

Material : Chess, or cheat hay (Bromus, spp.)

Total dry matter per ct. : 91.7

Protein per ct. : 6.9

Fat per ct. : 2.1

Fiber per ct. : 29.2

N-free extract per ct. : 46.1

Total minerals per ct. : 7.4

Calcium per ct. : 0.29

Phosphorus per ct. : 0.25

Nitrogen per ct. : 1.10

Potassium per ct. : 1.47

Material : Clover hay, alsike, all analyses

Total dry matter per ct. : 88.9

Protein per ct. : 12.1

Fat per ct. : 2.1

Fiber per ct. : 27.0

N-free extract per ct. : 39.9

Total minerals per ct. : 7.8

Calcium per ct. : 1.15

Phosphorus per ct. : 0.23

Nitrogen per ct. : 1.94

Potassium per ct. : 2.44

Material : Clover hay, alsike, in bloom

Total dry matter per ct. : 89.0

Protein per ct. : 13.4

Fat per ct. : 3.2

Fiber per ct. : 26.9

N-free extract per ct. : 37.7

Total minerals per ct. : 7.8

Calcium per ct. : 1.32

Phosphorus per ct. : 0.25

Nitrogen per ct. : 2.14

Potassium per ct. : 2.27

Material : Clover hay, Alyce

Total dry matter per ct. : 89.0

Protein per ct. : 10.9

Fat per ct. : 1.6

Fiber per ct. : 35.4

N-free extract per ct. : 35.5

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.74

Potassium per ct. : —

Material : Clover hay, bur

Total dry matter per ct. : 92.1

Protein per ct. : 18.4

Fat per ct. : 2.9

Fiber per ct. : 22.9

N-free extract per ct. : 37.8

Total minerals per ct. : 10.1

Calcium per ct. : 1.32

Phosphorus per ct. : 0.45

Nitrogen per ct. : 2.94

Potassium per ct. : 2.96

Material : Clover hay, crimson

Total dry matter per ct. : 89.5

Protein per ct. : 14.2

Fat per ct. : 2.2

Fiber per ct. : 27.4

N-free extract per ct. : 37.0

Total minerals per ct. : 8.7

Calcium per ct. : 1.23

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.27

Potassium per ct. : 2.79

Material : Clover hay, Ladino

Total dry matter per ct. : 88.0

Protein per ct. : 19.4

Fat per ct. : 3.2

Fiber per ct. : 20.7

N-free extract per ct. : 34.9

Total minerals per ct. : 9.8

Calcium per ct. : 1.32

Phosphorus per ct. : 0.29

Nitrogen per ct. : 3.10

Potassium per ct. : 2.78

Material : Clover, Ladino, and grass hay

Total dry matter per ct. : 88.0

Protein per ct. : 16.3

Fat per ct. : 2.2

Fiber per ct. : 20.7

N-free extract per ct. : 41.7

Total minerals per ct. : 7.1

Calcium per ct. : 1.05

Phosphorus per ct. : 0.26

Nitrogen per ct. : 2.61

Potassium per ct. : 1.97

Material : Clover hay, mammoth red

Total dry matter per ct. : 88.0

Protein per ct. : 11.7

Fat per ct. : 3.4

Fiber per ct. : 29.2

N-free extract per ct. : 37.0

Total minerals per ct. : 6.7

Calcium per ct. : —

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.87

Potassium per ct. : —

Material : Clover hay, red, all analyses

Total dry matter per ct. : 88.1

Protein per ct. : 11.8

Fat per ct. : 2.6

Fiber per ct. : 27.2

N-free extract per ct. : 40.1

Total minerals per ct. : 6.4

Calcium per ct. : 1.35

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.89

Potassium per ct. : 1.43

Material : Clover hay, red, leafy (less than 25% fiber)

Total dry matter per ct. : 88.1

Protein per ct. : 13.4

Fat per ct. : 3.1

Fiber per ct. : 23.6

N-free extract per ct. : 40.8

Total minerals per ct. : 7.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.14

Potassium per ct. : —

Material : Clover hay, red, stemmy (over 31% fiber)

Total dry matter per ct. : 88.2

Protein per ct. : 10.1

Fat per ct. : 2.1

Fiber per ct. : 34.1

N-free extract per ct. : 36.0

Total minerals per ct. : 5.9

Calcium per ct. : 0.99

Phosphorus per ct. : 0.15

Nitrogen per ct. : 1.62

Potassium per ct. : 1.77

Material : Clover hay, red, before bloom

Total dry matter per ct. : 88.1

Protein per ct. : 18.3

Fat per ct. : 3.6

Fiber per ct. : 18.0

N-free extract per ct. : 41.1

Total minerals per ct. : 7.1

Calcium per ct. : 1.69

Phosphorus per ct. : 0.28

Nitrogen per ct. : 2.93

Potassium per ct. : 2.26

Material : Clover hay, red, early to full bloom

Total dry matter per ct. : 88.1

Protein per ct. : 12.5

Fat per ct. : 3.5

Fiber per ct. : 26.1

N-free extract per ct. : 39.7

Total minerals per ct. : 6.3

Calcium per ct. : 1.47

Phosphorus per ct. : 0.22

Nitrogen per ct. : 2.00

Potassium per ct. : 1.73

Material : Clover hay, red, second cutting

Total dry matter per ct. : 88.1

Protein per ct. : 13.4

Fat per ct. : 2.9

Fiber per ct. : 24.5

N-free extract per ct. : 40.4

Total minerals per ct. : 6.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.14

Potassium per ct. : —

Material : Clover hay, sweet, first year

Total dry matter per ct. : 91.8

Protein per ct. : 16.5

Fat per ct. : 2.5

Fiber per ct. : 24.6

N-free extract per ct. : 39.7

Total minerals per ct. : 8.5

Calcium per ct. : 1.37

Phosphorus per ct. : 0.26

Nitrogen per ct. : 2.64

Potassium per ct. : 1.57

Material : Clover hay, sweet, second year

Total dry matter per ct. : 90.7

Protein per ct. : 13.5

Fat per ct. : 1.9

Fiber per ct. : 30.2

N-free extract per ct. : 37.6

Total minerals per ct. : 7.5

Calcium per ct. : 1.25

Phosphorus per ct. : 0.23

Nitrogen per ct. : 2.16

Potassium per ct. : 1.78

Material : Clover hay, white

Total dry matter per ct. : 88.0

Protein per ct. : 14.4

Fat per ct. : 2.4

Fiber per ct. : 22.5

N-free extract per ct. : 40.9

Total minerals per ct. : 7.8

Calcium per ct. : 1.16

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.30

Potassium per ct. : 1.66

Material : Clover leaves, sweet

Total dry matter per ct. : 92.2

Protein per ct. : 26.6

Fat per ct. : 3.2

Fiber per ct. : 9.5

N-free extract per ct. : 41.9

Total minerals per ct. : 11.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.26

Potassium per ct. : —

Material : Clover stems, sweet

Total dry matter per ct. : 92.7

Protein per ct. : 10.6

Fat per ct. : 1.1

Fiber per ct. : 38.0

N-free extract per ct. : 35.6

Total minerals per ct. : 7.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.70

Potassium per ct. : —

Material : Clover straw, crimson

Total dry matter per ct. : 87.7

Protein per ct. : 7.5

Fat per ct. : 1.5

Fiber per ct. : 38.8

N-free extract per ct. : 32.9

Total minerals per ct. : 7.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.20

Potassium per ct. : —

Material : Clover and mixed grassy, high in clover

Total dry matter per ct. : 89.7

Protein per ct. : 9.6

Fat per ct. : 2.7

Fiber per ct. : 28.8

N-free extract per ct. : 42.2

Total minerals per ct. : 6.2

Calcium per ct. : 0.90

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.54

Potassium per ct. : 1.46

Material : Clover and timothy hay, 30 to 50% clover

Total dry matter per ct. : 88.1

Protein per ct. : 8.6

Fat per ct. : 2.2

Fiber per ct. : 30.3

N-free extract per ct. : 41.2

Total minerals per ct. : 5.8

Calcium per ct. : 0.68

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.38

Potassium per ct. : 1.47

Material : Corn cobs, ground

Total dry matter per ct. : 90.4

Protein per ct. : 2.3

Fat per ct. : 0.4

Fiber per ct. : 32.1

N-free extract per ct. : 54.0

Total minerals per ct. : 1.6

Calcium per ct. : —

Phosphorus per ct. : 0.02

Nitrogen per ct. : 0.37

Potassium per ct. : 0.37

Material : Corn fodder, well-eared, very dry (from barn or in arid districts)

Total dry matter per ct. : 91.1

Protein per ct. : 7.8

Fat per ct. : 2.2

Fiber per ct. : 27.1

N-free extract per ct. : 47.6

Total minerals per ct. : 6.4

Calcium per ct. : 0.24

Phosphorus per ct. : 0.16

Nitrogen per ct. : 1.25

Potassium per ct. : 0.82

Material : Corn fodder, high in water

Total dry matter per ct. : 60.7

Protein per ct. : 4.8

Fat per ct. : 1.4

Fiber per ct. : 16.7

N-free extract per ct. : 34.2

Total minerals per ct. : 3.6

Calcium per ct. : 0.16

Phosphorus per ct. : 0.11

Nitrogen per ct. : 0.77

Potassium per ct. : 0.55

Material : Corn fodder, sweet corn

Total dry matter per ct. : 87.7

Protein per ct. : 9.2

Fat per ct. : 1.8

Fiber per ct. : 26.4

N-free extract per ct. : 41.3

Total minerals per ct. : 9.0

Calcium per ct. : —

Phosphorus per ct. : 0.17

Nitrogen per ct. : 1.47

Potassium per ct. : 0.98

Material : Corn husks, dried

Total dry matter per ct. : 85.0

Protein per ct. : 3.4

Fat per ct. : 0.9

Fiber per ct. : 28.2

N-free extract per ct. : 49.6

Total minerals per ct. : 2.9

Calcium per ct. : 0.15

Phosphorus per ct. : 0.12

Nitrogen per ct. : 0.54

Potassium per ct. : 0.55

Material : Corn leaves, dried

Total dry matter per ct. : 82.8

Protein per ct. : 7.7

Fat per ct. : 1.9

Fiber per ct. : 23.9

N-free extract per ct. : 42.6

Total minerals per ct. : 6.7

Calcium per ct. : 0.29

Phosphorus per ct. : 0.10

Nitrogen per ct. : 1.23

Potassium per ct. : 0.36

Material : Corn stalks, dried

Total dry matter per ct. : 82.8

Protein per ct. : 4.7

Fat per ct. : 1.5

Fiber per ct. : 28.0

N-free extract per ct. : 43.3

Total minerals per ct. : 5.3

Calcium per ct. : 0.25

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.75

Potassium per ct. : 0.50

Material : Corn stover (ears removed), very dry

Total dry matter per ct. : 90.6

Protein per ct. : 5.9

Fat per ct. : 1.6

Fiber per ct. : 30.8

N-free extract per ct. : 4.65

Total minerals per ct. : 5.8

Calcium per ct. : 0.29

Phosphorus per ct. : 0.05

Nitrogen per ct. : 0.94

Potassium per ct. : 0.67

Material : Corn stover, high in water

Total dry matter per ct. : 59.0

Protein per ct. : 3.9

Fat per ct. : 1.0

Fiber per ct. : 20.1

N-free extract per ct. : 30.2

Total minerals per ct. : 3.8

Calcium per ct. : 0.19

Phosphorus per ct. : 0.04

Nitrogen per ct. : 0.62

Potassium per ct. : 0.44

Material : Corn tops, dried

Total dry matter per ct. : 82.1

Protein per ct. : 5.6

Fat per ct. : 1.5

Fiber per ct. : 27.4

N-free extract per ct. : 42.0

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.90

Potassium per ct. : —

Material : Cotton bolls, dried

Total dry matter per ct. : 90.8

Protein per ct. : 8.7

Fat per ct. : 2.4

Fiber per ct. : 30.8

N-free extract per ct. : 42.0

Total minerals per ct. : 6.9

Calcium per ct. : 0.61

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.39

Potassium per ct. : 3.18

Material : Cotton leaves, dried

Total dry matter per ct. : 91.7

Protein per ct. : 15.3

Fat per ct. : 6.8

Fiber per ct. : 10.3

N-free extract per ct. : 43.5

Total minerals per ct. : 15.8

Calcium per ct. : 4.58

Phosphorus per ct. : 0.18

Nitrogen per ct. : 2.45

Potassium per ct. : 1.36

Material : Cotton stems, dried

Total dry matter per ct. : 92.4

Protein per ct. : 5.8

Fat per ct. : 0.9

Fiber per ct. : 44.0

N-free extract per ct. : 37.5

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Cottonseed hulls

Total dry matter per ct. : 90.7

Protein per ct. : 3.9

Fat per ct. : 0.9

Fiber per ct. : 46.1

N-free extract per ct. : 37.2

Total minerals per ct. : 2.6

Calcium per ct. : 0.14

Phosphorus per ct. : 0.07

Nitrogen per ct. : 0.62

Potassium per ct. : 0.87

Material : Cottonseed hull bran

Total dry matter per ct. : 91.0

Protein per ct. : 3.4

Fat per ct. : 0.9

Fiber per ct. : 37.2

N-free extract per ct. : 46.7

Total minerals per ct. : 2.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.54

Potassium per ct. : —

Material : Cowpea hay, all analyses

Total dry matter per ct. : 90.4

Protein per ct. : 18.6

Fat per ct. : 2.6

Fiber per ct. : 23.3

N-free extract per ct. : 34.6

Total minerals per ct. : 11.3

Calcium per ct. : 1.37

Phosphorus per ct. : 0.29

Nitrogen per ct. : 2.98

Potassium per ct. : 1.51

Material : Cowpea hay, in bloom to early pod

Total dry matter per ct. : 89.9

Protein per ct. : 18.1

Fat per ct. : 3.2

Fiber per ct. : 21.8

N-free extract per ct. : 36.7

Total minerals per ct. : 10.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.90

Potassium per ct. : —

Material : Cowpea hay, ripe

Total dry matter per ct. : 90.0

Protein per ct. : 10.1

Fat per ct. : 2.5

Fiber per ct. : 29.2

N-free extract per ct. : 41.8

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.62

Potassium per ct. : —

Material : Cowpea straw

Total dry matter per ct. : 91.5

Protein per ct. : 6.8

Fat per ct. : 1.2

Fiber per ct. : 44.5

N-free extract per ct. : 33.6

Total minerals per ct. : 5.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.09

Potassium per ct. : —

Material : Crabgrass hay

Total dry matter per ct. : 90.5

Protein per ct. : 8.0

Fat per ct. : 2.4

Fiber per ct. : 28.7

N-free extract per ct. : 42.9

Total minerals per ct. : 8.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.28

Potassium per ct. : —

Material : Durra fodder

Total dry matter per ct. : 89.9

Protein per ct. : 6.4

Fat per ct. : 2.8

Fiber per ct. : 24.1

N-free extract per ct. : 51.4

Total minerals per ct. : 5.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.02

Potassium per ct. : —

Material : Emmer hay

Total dry matter per ct. : 90.0

Protein per ct. : .97

Fat per ct. : 2.0

Fiber per ct. : 32.8

N-free extract per ct. : 36.4

Total minerals per ct. : 9.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.55

Potassium per ct. : —

Material : Fescue hay, meadow

Total dry matter per ct. : 89.2

Protein per ct. : 7.0

Fat per ct. : 1.9

Fiber per ct. : 30.3

N-free extract per ct. : 43.2

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.12

Potassium per ct. : 1.43

Material : Fescue hay, native western (Festuca, spp.)

Total dry matter per ct. : 90.0

Protein per ct. : 8.5

Fat per ct. : 2.0

Fiber per ct. : 31.0

N-free extract per ct. : 42.8

Total minerals per ct. : 5.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.36

Potassium per ct. : —

Material : Feterita fodder, very dry

Total dry matter per ct. : 88.0

Protein per ct. : 8.0

Fat per ct. : 2.1

Fiber per ct. : 18.7

N-free extract per ct. : 51.5

Total minerals per ct. : 7.7

Calcium per ct. : 0.30

Phosphorus per ct. : 0.21

Nitrogen per ct. : 1.28

Potassium per ct. : —

Material : Feterita stover

Total dry matter per ct. : 86.3

Protein per ct. : 5.2

Fat per ct. : 1.7

Fiber per ct. : 29.2

N-free extract per ct. : 41.9

Total minerals per ct. : 8.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.83

Potassium per ct. : —

Material : Flat pea hay

Total dry matter per ct. : 92.3

Protein per ct. : 22.7

Fat per ct. : 3.2

Fiber per ct. : 27.7

N-free extract per ct. : 32.0

Total minerals per ct. : 6.7

Calcium per ct. : —

Phosphorus per ct. : 0.30

Nitrogen per ct. : 3.63

Potassium per ct. : 2.02

Material : Flax plant by product

Total dry matter per ct. : 91.9

Protein per ct. : 6.4

Fat per ct. : 2.1

Fiber per ct. : 44.4

N-free extract per ct. : 33.1

Total minerals per ct. : 5.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.02

Potassium per ct. : —

Material : Flax straw

Total dry matter per ct. : 92.8

Protein per ct. : 7.2

Fat per ct. : 3.2

Fiber per ct. : 42.5

N-free extract per ct. : 32.9

Total minerals per ct. : 7.0

Calcium per ct. : 0.48

Phosphorus per ct. : 0.07

Nitrogen per ct. : 1.15

Potassium per ct. : 0.73

Material : Fowl meadow grass hay

Total dry matter per ct. : 87.4

Protein per ct. : 8.7

Fat per ct. : 2.3

Fiber per ct. : 29.7

N-free extract per ct. : 39.5

Total minerals per ct. : 7.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.39

Potassium per ct. : —

Material : Furze, dried

Total dry matter per ct. : 94.5

Protein per ct. : 11.6

Fat per ct. : 2.0

Fiber per ct. : 38.5

N-free extract per ct. : 35.5

Total minerals per ct. : 7.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.86

Potassium per ct. : —

Material : Gama grass hay (Tripsacum dactyloides)

Total dry matter per ct. : 88.2

Protein per ct. : 6.7

Fat per ct. : 1.8

Fiber per ct. : 30.4

N-free extract per ct. : 43.1

Total minerals per ct. : 6.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.07

Potassium per ct. : —

Material : Grama grass hay (Bouteloua, spp.)

Total dry matter per ct. : 89.8

Protein per ct. : 5.8

Fat per ct. : 1.6

Fiber per ct. : 28.9

N-free extract per ct. : 45.6

Total minerals per ct. : 7.9

Calcium per ct. : 0.34

Phosphorus per ct. : 0.18

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Grass hay, mixed, eastern states, good quality

Total dry matter per ct. : 89.0

Protein per ct. : 7.0

Fat per ct. : 2.5

Fiber per ct. : 30.9

N-free extract per ct. : 43.1

Total minerals per ct. : 5.5

Calcium per ct. : 0.48

Phosphorus per ct. : 0.21

Nitrogen per ct. : 1.12

Potassium per ct. : 1.20

Material : Grass hay, mixed, second cutting

Total dry matter per ct. : 89.0

Protein per ct. : 12.3

Fat per ct. : 3.3

Fiber per ct. : 24.8

N-free extract per ct. : 41.7

Total minerals per ct. : 6.9

Calcium per ct. : 0.79

Phosphorus per ct. : 0.31

Nitrogen per ct. : 1.97

Potassium per ct. : 1.15

Material : Grass straw

Total dry matter per ct. : 85.0

Protein per ct. : 4.5

Fat per ct. : 2.0

Fiber per ct. : 35.0

N-free extract per ct. : 37.8

Total minerals per ct. : 5.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.72

Potassium per ct. : —

Material : Guar hay (Cyamposis psoraloides)

Total dry matter per ct. : 90.7

Protein per ct. : 16.5

Fat per ct. : 1.3

Fiber per ct. : 19.3

N-free extract per ct. : 41.2

Total minerals per ct. : 12.4

Calcium per ct. : —

Phosphorus per ct. : 2.64

Nitrogen per ct. : —

Potassium per ct. : —

Material : Hegari fodder

Total dry matter per ct. : 86.0

Protein per ct. : 6.2

Fat per ct. : 1.7

Fiber per ct. : 18.1

N-free extract per ct. : 52.5

Total minerals per ct. : 7.5

Calcium per ct. : 0.27

Phosphorus per ct. : 0.16

Nitrogen per ct. : 0.99

Potassium per ct. : —

Material : Hegari stover

Total dry matter per ct. : 87.0

Protein per ct. : 5.6

Fat per ct. : 1.8

Fiber per ct. : 28.0

N-free extract per ct. : 41.7

Total minerals per ct. : 9.9

Calcium per ct. : 0.33

Phosphorus per ct. : 0.08

Nitrogen per ct. : 0.90

Potassium per ct. : —

Material : Hops, spent, dried

Total dry matter per ct. : 93.8

Protein per ct. : 23.0

Fat per ct. : 3.6

Fiber per ct. : 24.5

N-free extract per ct. : 37.4

Total minerals per ct. : 5.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.68

Potassium per ct. : —

Material : Horse bean hay

Total dry matter per ct. : 91.5

Protein per ct. : 13.4

Fat per ct. : 0.8

Fiber per ct. : 22.0

N-free extract per ct. : 49.8

Total minerals per ct. : 5.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.14

Potassium per ct. : —

Material : Horse bean straw

Total dry matter per ct. : 87.9

Protein per ct. : 8.6

Fat per ct. : 1.4

Fiber per ct. : 36.4

N-free extract per ct. : 33.1

Total minerals per ct. : 8.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.38

Potassium per ct. : —

Material : Hyacinth bean hay (Dilichos lablab)

Total dry matter per ct. : 90.2

Protein per ct. : 14.8

Fat per ct. : 1.4

Fiber per ct. : 33.6

N-free extract per ct. : 33.6

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.37

Potassium per ct. : —

Material : Johnson grass hay

Total dry matter per ct. : 90.1

Protein per ct. : 6.5

Fat per ct. : 2.1

Fiber per ct. : 30.4

N-free extract per ct. : 43.7

Total minerals per ct. : 7.4

Calcium per ct. : 0.87

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.04

Potassium per ct. : 1.22

Material : June grass hay, western (Koeleria cristata)

Total dry matter per ct. : 88.3

Protein per ct. : 8.1

Fat per ct. : 2.5

Fiber per ct. : 30.4

N-free extract per ct. : 40.5

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.30

Potassium per ct. : —

Material : Kafir fodder, very dry

Total dry matter per ct. : 90.0

Protein per ct. : 8.7

Fat per ct. : 2.6

Fiber per ct. : 25.5

N-free extract per ct. : 44.2

Total minerals per ct. : 9.0

Calcium per ct. : 0.35

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.39

Potassium per ct. : 1.53

Material : Kafir fodder, high in water

Total dry matter per ct. : 71.7

Protein per ct. : 6.5

Fat per ct. : 2.7

Fiber per ct. : 21.6

N-free extract per ct. : 37.6

Total minerals per ct. : 3.3

Calcium per ct. : 0.28

Phosphorus per ct. : 0.14

Nitrogen per ct. : 1.04

Potassium per ct. : 1.23

Material : Kafir stover, very dry

Total dry matter per ct. : 90.0

Protein per ct. : 5.5

Fat per ct. : 1.8

Fiber per ct. : 29.5

N-free extract per ct. : 44.3

Total minerals per ct. : 8.9

Calcium per ct. : 0.54

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.88

Potassium per ct. : —

Material : Kafir stover, high in water

Total dry matter per ct. : 72.7

Protein per ct. : 3.8

Fat per ct. : 1.3

Fiber per ct. : 23.7

N-free extract per ct. : 36.6

Total minerals per ct. : 7.3

Calcium per ct. : 0.44

Phosphorus per ct. : 0.07

Nitrogen per ct. : 0.61

Potassium per ct. : —

Material : Koahaole forage, dried

Total dry matter per ct. : 88.7

Protein per ct. : 12.7

Fat per ct. : 1.9

Fiber per ct. : 29.8

N-free extract per ct. : 39.2

Total minerals per ct. : 5.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.03

Potassium per ct. : —

Material : Kochia scoparia hay

Total dry matter per ct. : 90.0

Protein per ct. : 11.4

Fat per ct. : 1.5

Fiber per ct. : 23.6

N-free extract per ct. : 40.7

Total minerals per ct. : 12.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.82

Potassium per ct. : —

Material : Kudzu hay

Total dry matter per ct. : 89.0

Protein per ct. : 15.9

Fat per ct. : 2.5

Fiber per ct. : 28.6

N-free extract per ct. : 35.1

Total minerals per ct. : 6.9

Calcium per ct. : 2.78

Phosphorus per ct. : 0.21

Nitrogen per ct. : 2.54

Potassium per ct. : —

Material : Lespedeza hay, annual, all analyses

Total dry matter per ct. : 89.2

Protein per ct. : 12.7

Fat per ct. : 2.4

Fiber per ct. : 26.7

N-free extract per ct. : 42.2

Total minerals per ct. : 5.2

Calcium per ct. : 0.98

Phosphorus per ct. : 0.18

Nitrogen per ct. : 2.03

Potassium per ct. : 0.91

Material : Lespedeza hay, annual, before bloom

Total dry matter per ct. : 89.1

Protein per ct. : 14.3

Fat per ct. : 2.7

Fiber per ct. : 22.7

N-free extract per ct. : 43.0

Total minerals per ct. : 6.4

Calcium per ct. : 1.04

Phosphorus per ct. : 0.19

Nitrogen per ct. : 2.29

Potassium per ct. : 1.06

Material : Lespedeza hay, annual, in bloom

Total dry matter per ct. : 89.1

Protein per ct. : 13.0

Fat per ct. : 1.8

Fiber per ct. : 26.5

N-free extract per ct. : 42.7

Total minerals per ct. : 5.1

Calcium per ct. : 1.02

Phosphorus per ct. : 0.18

Nitrogen per ct. : 2.08

Potassium per ct. : 0.94

Material : Lespedeza hay, annual, after bloom

Total dry matter per ct. : 89.1

Protein per ct. : 11.5

Fat per ct. : 1.9

Fiber per ct. : 32.6

N-free extract per ct. : 38.6

Total minerals per ct. : 4.5

Calcium per ct. : 0.90

Phosphorus per ct. : 0.15

Nitrogen per ct. : 1.84

Potassium per ct. : 0.82

Material : Lespedeza hay, perennial

Total dry matter per ct. : 89.0

Protein per ct. : 13.2

Fat per ct. : 1.7

Fiber per ct. : 26.5

N-free extract per ct. : 42.7

Total minerals per ct. : 4.9

Calcium per ct. : 0.92

Phosphorus per ct. : 0.22

Nitrogen per ct. : 2.11

Potassium per ct. : 0.98

Material : Lespedeza leaves, annual

Total dry matter per ct. : 89.2

Protein per ct. : 17.1

Fat per ct. : 2.9

Fiber per ct. : 19.7

N-free extract per ct. : 43.1

Total minerals per ct. : 6.4

Calcium per ct. : 1.30

Phosphorus per ct. : 0.20

Nitrogen per ct. : 2.74

Potassium per ct. : 0.92

Material : Lespedeza stems, annual

Total dry matter per ct. : 89.2

Protein per ct. : 8.3

Fat per ct. : 1.0

Fiber per ct. : 38.5

N-free extract per ct. : 37.7

Total minerals per ct. : 3.7

Calcium per ct. : 0.64

Phosphorus per ct. : 0.13

Nitrogen per ct. : 1.33

Potassium per ct. : 0.89

Material : Lespedeza straw

Total dry matter per ct. : 90.0

Protein per ct. : 6.8

Fat per ct. : 2.3

Fiber per ct. : 29.2

N-free extract per ct. : 47.1

Total minerals per ct. : 4.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.09

Potassium per ct. : —

Material : Lovegrass hay, weeping

Total dry matter per ct. : 91.2

Protein per ct. : 9.2

Fat per ct. : 2.8

Fiber per ct. : 30.9

N-free extract per ct. : 43.4

Total minerals per ct. : 4.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.47

Potassium per ct. : —

Material : Marsh or swamp hay, good quality

Total dry matter per ct. : 90.2

Protein per ct. : 7.7

Fat per ct. : 2.3

Fiber per ct. : 28.2

N-free extract per ct. : 44.3

Total minerals per ct. : 7.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.23

Potassium per ct. : —

Material : Millet hay, foxtail varieties

Total dry matter per ct. : 87.6

Protein per ct. : 8.2

Fat per ct. : 2.7

Fiber per ct. : 25.3

N-free extract per ct. : 44.7

Total minerals per ct. : 6.7

Calcium per ct. : 0.29

Phosphorus per ct. : 0.16

Nitrogen per ct. : 1.31

Potassium per ct. : 1.70

Material : Millet hay, hog millet, or proso

Total dry matter per ct. : 90.3

Protein per ct. : 9.3

Fat per ct. : 2.2

Fiber per ct. : 23.9

N-free extract per ct. : 47.6

Total minerals per ct. : 7.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.49

Potassium per ct. : —

Material : Millet hay, Japanese

Total dry matter per ct. : 86.8

Protein per ct. : 8.3

Fat per ct. : 1.6

Fiber per ct. : 27.7

N-free extract per ct. : 40.8

Total minerals per ct. : 8.4

Calcium per ct. : 0.20

Phosphorus per ct. : —

Nitrogen per ct. : 1.33

Potassium per ct. : 2.10

Material : Millet hay, pearl, or cat-tail

Total dry matter per ct. : 87.2

Protein per ct. : 6.7

Fat per ct. : 1.7

Fiber per ct. : 33.0

N-free extract per ct. : 36.8

Total minerals per ct. : 9.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.07

Potassium per ct. : —

Material : Millet straw

Total dry matter per ct. : 90.0

Protein per ct. : 3.8

Fat per ct. : 1.6

Fiber per ct. : 37.5

N-free extract per ct. : 41.6

Total minerals per ct. : 5.5

Calcium per ct. : 0.08

Phosphorus per ct. : —

Nitrogen per ct. : 0.61

Potassium per ct. : 1.44

Material : Milo fodder

Total dry matter per ct. : 88.5

Protein per ct. : 8.0

Fat per ct. : 3.3

Fiber per ct. : 21.9

N-free extract per ct. : 48.4

Total minerals per ct. : 6.9

Calcium per ct. : 0.35

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.28

Potassium per ct. : —

Material : Milo stover

Total dry matter per ct. : 91.0

Protein per ct. : 3.2

Fat per ct. : 1.1

Fiber per ct. : 29.1

N-free extract per ct. : 48.1

Total minerals per ct. : 9.5

Calcium per ct. : 0.58

Phosphorus per ct. : 0.11

Nitrogen per ct. : 0.51

Potassium per ct. : —

Material : Mint hay

Total dry matter per ct. : 88.3

Protein per ct. : 12.7

Fat per ct. : 2.1

Fiber per ct. : 20.3

N-free extract per ct. : 45.6

Total minerals per ct. : 7.6

Calcium per ct. : 1.51

Phosphorus per ct. : 0.19

Nitrogen per ct. : 2.03

Potassium per ct. : —

Material : Mixed hay, good, less than 30% legumes

Total dry matter per ct. : 88.0

Protein per ct. : 8.3

Fat per ct. : 1.8

Fiber per ct. : 30.7

N-free extract per ct. : 41.8

Total minerals per ct. : 5.4

Calcium per ct. : 0.61

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.33

Potassium per ct. : 1.47

Material : Mixed hay, good, more than 30% legumes

Total dry matter per ct. : 88.0

Protein per ct. : 9.2

Fat per ct. : 1.9

Fiber per ct. : 28.1

N-free extract per ct. : 42.8

Total minerals per ct. : 6.0

Calcium per ct. : 0.90

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.47

Potassium per ct. : 1.46

Material : Mixed hay, cut very early

Total dry matter per ct. : 90.0

Protein per ct. : 13.3

Fat per ct. : 2.7

Fiber per ct. : 25.3

N-free extract per ct. : 39.4

Total minerals per ct. : 9.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.13

Potassium per ct. : —

Material : Napier grass hay

Total dry matter per ct. : 89.1

Protein per ct. : 8.2

Fat per ct. : 1.8

Fiber per ct. : 34.0

N-free extract per ct. : 34.6

Total minerals per ct. : 10.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.31

Potassium per ct. : —

Material : Natal grass hay

Total dry matter per ct. : 90.2

Protein per ct. : 7.4

Fat per ct. : 1.8

Fiber per ct. : 36.8

N-free extract per ct. : 39.2

Total minerals per ct. : 5.0

Calcium per ct. : 0.45

Phosphorus per ct. : 0.29

Nitrogen per ct. : 1.18

Potassium per ct. : —

Material : Native hay, western mt. states, good quality

Total dry matter per ct. : 90.0

Protein per ct. : 8.1

Fat per ct. : 2.1

Fiber per ct. : 29.8

N-free extract per ct. : 43.2

Total minerals per ct. : 6.8

Calcium per ct. : 0.39

Phosphorus per ct. : 0.12

Nitrogen per ct. : 1.30

Potassium per ct. : —

Material : Native hay, western mt. states, mature and weathered

Total dry matter per ct. : 90.0

Protein per ct. : 3.9

Fat per ct. : 1.4

Fiber per ct. : 33.6

N-free extract per ct. : 43.6

Total minerals per ct. : 7.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.62

Potassium per ct. : —

Material : Needle grass hay (Stipa, spp.)

Total dry matter per ct. : 88.1

Protein per ct. : 7.2

Fat per ct. : 2.0

Fiber per ct. : 30.8

N-free extract per ct. : 41.9

Total minerals per ct. : 6.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.15

Potassium per ct. : —

Material : Oak leaves, live oak, dried

Total dry matter per ct. : 93.8

Protein per ct. : 9.3

Fat per ct. : 2.7

Fiber per ct. : 29.9

N-free extract per ct. : 45.3

Total minerals per ct. : 6.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.49

Potassium per ct. : —

Material : Oat chaff

Total dry matter per ct. : 91.8

Protein per ct. : 5.9

Fat per ct. : 2.4

Fiber per ct. : 25.7

N-free extract per ct. : 46.3

Total minerals per ct. : 11.5

Calcium per ct. : 0.80

Phosphorus per ct. : 0.30

Nitrogen per ct. : 0.94

Potassium per ct. : 0.86

Material : Oat hay

Total dry matter per ct. : 88.1

Protein per ct. : 8.2

Fat per ct. : 2.7

Fiber per ct. : 28.1

N-free extract per ct. : 42.2

Total minerals per ct. : 6.9

Calcium per ct. : 0.21

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.31

Potassium per ct. : 0.83

Material : Oat hay, wild (Avena fatua)

Total dry matter per ct. : 92.5

Protein per ct. : 6.6

Fat per ct. : 2.6

Fiber per ct. : 32.5

N-free extract per ct. : 44.0

Total minerals per ct. : 6.8

Calcium per ct. : 0.22

Phosphorus per ct. : 0.25

Nitrogen per ct. : 1.06

Potassium per ct. : —

Material : Oat hulls

Total dry matter per ct. : 92.8

Protein per ct. : 4.5

Fat per ct. : 1.3

Fiber per ct. : 29.7

N-free extract per ct. : 50.8

Total minerals per ct. : 6.5

Calcium per ct. : 0.20

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.78

Potassium per ct. : 0.48

Material : Oat straw

Total dry matter per ct. : 89.7

Protein per ct. : 4.1

Fat per ct. : 2.2

Fiber per ct. : 36.1

N-free extract per ct. : 41.0

Total minerals per ct. : 6.3

Calcium per ct. : 0.19

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.66

Potassium per ct. : 1.35

Material : Oat grass hay, tall

Total dry matter per ct. : 88.7

Protein per ct. : 7.5

Fat per ct. : 2.4

Fiber per ct. : 30.1

N-free extract per ct. : 42.7

Total minerals per ct. : 6.0

Calcium per ct. : —

Phosphorus per ct. : 0.14

Nitrogen per ct. : 1.20

Potassium per ct. : 1.36

Material : Orchard grass hay, early-cut

Total dry matter per ct. : 88.6

Protein per ct. : 7.7

Fat per ct. : 2.9

Fiber per ct. : 30.5

N-free extract per ct. : 40.7

Total minerals per ct. : 6.8

Calcium per ct. : 0.19

Phosphorus per ct. : 0.17

Nitrogen per ct. : 1.23

Potassium per ct. : 1.61

Material : Picnic grass hay (Panicum, spp.)

Total dry matter per ct. : 92.1

Protein per ct. : 8.3

Fat per ct. : 2.3

Fiber per ct. : 29.5

N-free extract per ct. : 44.9

Total minerals per ct. : 7.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.33

Potassium per ct. : —

Material : Para grass hay

Total dry matter per ct. : 90.2

Protein per ct. : 4.6

Fat per ct. : 0.9

Fiber per ct. : 33.6

N-free extract per ct. : 44.5

Total minerals per ct. : 6.6

Calcium per ct. : 0.35

Phosphorus per ct. : 0.35

Nitrogen per ct. : 0.74

Potassium per ct. : 1.44

Material : Pasture grasses and clovers, mixed, from closely grazed, fertile pasture, dried (northern states)

Total dry matter per ct. : 90.0

Protein per ct. : 20.3

Fat per ct. : 3.6

Fiber per ct. : 19.7

N-free extract per ct. : 38.7

Total minerals per ct. : 7.7

Calcium per ct. : 0.58

Phosphorus per ct. : 0.32

Nitrogen per ct. : 3.25

Potassium per ct. : 2.18

Material : Pasture grasses, mixed, from poor to fair pasture, before heading out, dried

Total dry matter per ct. : 90.0

Protein per ct. : 14.1

Fat per ct. : 2.3

Fiber per ct. : 19.4

N-free extract per ct. : 43.2

Total minerals per ct. : 11.0

Calcium per ct. : 0.41

Phosphorus per ct. : 0.12

Nitrogen per ct. : 2.26

Potassium per ct. : 0.74

Material : Pasture grass, western plains, growing, dried

Total dry matter per ct. : 90.0

Protein per ct. : 11.6

Fat per ct. : 2.5

Fiber per ct. : 28.0

N-free extract per ct. : 40.2

Total minerals per ct. : 7.7

Calcium per ct. : 0.37

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.86

Potassium per ct. : —

Material : Pasture grass, western plains, mature, dried

Total dry matter per ct. : 90.0

Protein per ct. : 4.6

Fat per ct. : 2.3

Fiber per ct. : 31.9

N-free extract per ct. : 45.3

Total minerals per ct. : 5.9

Calcium per ct. : 0.34

Phosphorus per ct. : 0.14

Nitrogen per ct. : 0.74

Potassium per ct. : —

Material : Pasture grass, western plains, mature and weathered

Total dry matter per ct. : 90.0

Protein per ct. : 3.3

Fat per ct. : 1.8

Fiber per ct. : 34.1

N-free extract per ct. : 44.5

Total minerals per ct. : 6.3

Calcium per ct. : 0.33

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.53

Potassium per ct. : —

Material : Pasture grass and other forage on western mt. ranges, spring, dried

Total dry matter per ct. : 90.0

Protein per ct. : 17.0

Fat per ct. : 3.1

Fiber per ct. : 14.0

N-free extract per ct. : 49.1

Total minerals per ct. : 6.8

Calcium per ct. : 1.21

Phosphorus per ct. : 0.38

Nitrogen per ct. : 2.72

Potassium per ct. : —

Material : Pasture grass and other forage on western mt. ranges, autumn, dried

Total dry matter per ct. : 90.0

Protein per ct. : 8.8

Fat per ct. : 4.3

Fiber per ct. : 17.4

N-free extract per ct. : 51.4

Total minerals per ct. : 8.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.41

Potassium per ct. : —

Material : Pea hay, field

Total dry matter per ct. : 89.3

Protein per ct. : 14.9

Fat per ct. : 3.3

Fiber per ct. : 24.3

N-free extract per ct. : 39.1

Total minerals per ct. : 7.7

Calcium per ct. : 1.22

Phosphorus per ct. : 0.25

Nitrogen per ct. : 2.38

Potassium per ct. : 1.25

Material : Pea straw, field

Total dry matter per ct. : 90.2

Protein per ct. : 6.1

Fat per ct. : 1.6

Fiber per ct. : 33.1

N-free extract per ct. : 44.0

Total minerals per ct. : 5.4

Calcium per ct. : —

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.98

Potassium per ct. : 1.08

Material : Pea-and-oat hay

Total dry matter per ct. : 89.1

Protein per ct. : 12.1

Fat per ct. : 2.9

Fiber per ct. : 27.2

N-free extract per ct. : 39.1

Total minerals per ct. : 7.8

Calcium per ct. : 0.72

Phosphorus per ct. : 0.22

Nitrogen per ct. : 1.94

Potassium per ct. : 1.04

Material : Peanut hay, without nuts

Total dry matter per ct. : 90:7

Protein per ct. : 10.1

Fat per ct. : 3.3

Fiber per ct. : 23.4

N-free extract per ct. : 44.2

Total minerals per ct. : 9.7

Calcium per ct. : 1.12

Phosphorus per ct. : 0.13

Nitrogen per ct. : 1.62

Potassium per ct. : 1.25

Material : Peanut hay, with nuts

Total dry matter per ct. : 92.0

Protein per ct. : 13.4

Fat per ct. : 12.6

Fiber per ct. : 23.0

N-free extract per ct. : 34.9

Total minerals per ct. : 8.1

Calcium per ct. : 1.13

Phosphorus per ct. : 0.15

Nitrogen per ct. : 2.14

Potassium per ct. : 0.85

Material : Peanut hay, mowed

Total dry matter per ct. : 91.4

Protein per ct. : 10.6

Fat per ct. : 5.1

Fiber per ct. : 23.8

N-free extract per ct. : 42.2

Total minerals per ct. : 9.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.70

Potassium per ct. : —

Material : Peanut hulls, with a few nuts

Total dry matter per ct. : 92.3

Protein per ct. : 6.7

Fat per ct. : 1.2

Fiber per ct. : 60.3

N-free extract per ct. : 19.7

Total minerals per ct. : 4.4

Calcium per ct. : 0.30

Phosphorus per ct. : 0.07

Nitrogen per ct. : 1.07

Potassium per ct. : 0.82

Material : Peavine hay, from pea-cannery vines, sun-cured

Total dry matter per ct. : 86.3

Protein per ct. : 11.9

Fat per ct. : 2.4

Fiber per ct. : 23.0

N-free extract per ct. : 42.2

Total minerals per ct. : 6.8

Calcium per ct. : 1.48

Phosphorus per ct. : 0.16

Nitrogen per ct. : 1.90

Potassium per ct. : —

Material : Prairie hay, western, good quality

Total dry matter per ct. : 90.7

Protein per ct. : .57

Fat per ct. : 2.3

Fiber per ct. : 30.4

N-free extract per ct. : 44.9

Total minerals per ct. : 7.4

Calcium per ct. : 0.36

Phosphorus per ct. : 0.18

Nitrogen per ct. : 0.91

Potassium per ct. : —

Material : Prairie hay, western, mature

Total dry matter per ct. : 91.7

Protein per ct. : 3.8

Fat per ct. : 2.4

Fiber per ct. : 31.9

N-free extract per ct. : 47.1

Total minerals per ct. : 6.5

Calcium per ct. : 0.28

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.61

Potassium per ct. : 0.49

Material : Quack grass hay

Total dry matter per ct. : 89.0

Protein per ct. : 6.9

Fat per ct. : 1.9

Fiber per ct. : 34.5

N-free extract per ct. : 38.8

Total minerals per ct. : 6.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.10

Potassium per ct. : —

Material : Ramie meal

Total dry matter per ct. : 92.2

Protein per ct. : 19.2

Fat per ct. : 3.8

Fiber per ct. : 20.1

N-free extract per ct. : 35.9

Total minerals per ct. : 13.2

Calcium per ct. : 4.32

Phosphorus per ct. : 0.22

Nitrogen per ct. : 3.07

Potassium per ct. : —

Material : Red top hay

Total dry matter per ct. : 91.0

Protein per ct. : 7.2

Fat per ct. : 2.3

Fiber per ct. : 29.3

N-free extract per ct. : 45.3

Total minerals per ct. : 6.9

Calcium per ct. : 0.33

Phosphorus per ct. : 0.23

Nitrogen per ct. : 1.15

Potassium per ct. : 1.93

Material : Reed canary grass hay

Total dry matter per ct. : 91.1

Protein per ct. : 7.7

Fat per ct. : 2.3

Fiber per ct. : 29.2

N-free extract per ct. : 44.3

Total minerals per ct. : 7.6

Calcium per ct. : 0.33

Phosphorus per ct. : 0.16

Nitrogen per ct. : 1.23

Potassium per ct. : —

Material : Rescue grass hay

Total dry matter per ct. : 90.2

Protein per ct. : 9.8

Fat per ct. : 3.2

Fiber per ct. : 24.6

N-free extract per ct. : 44.5

Total minerals per ct. : 8.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.57

Potassium per ct. : —

Material : Rhodes grass hay

Total dry matter per ct. : 89.0

Protein per ct. : 5.7

Fat per ct. : 1.3

Fiber per ct. : 31.7

N-free extract per ct. : 41.8

Total minerals per ct. : 8.5

Calcium per ct. : 0.35

Phosphorus per ct. : 0.27

Nitrogen per ct. : 0.91

Potassium per ct. : 1.18

Material : Rice hulls

Total dry matter per ct. : 92.0

Protein per ct. : 3.0

Fat per ct. : 0.8

Fiber per ct. : 40.7

N-free extract per ct. : 28.4

Total minerals per ct. : 19.1

Calcium per ct. : 0.08

Phosphorus per ct. : 0.08

Nitrogen per ct. : 0.48

Potassium per ct. : 0.31

Material : Rice straw

Total dry matter per ct. : 92.5

Protein per ct. : 3.9

Fat per ct. : 1.4

Fiber per ct. : 33.5

N-free extract per ct. : 39.2

Total minerals per ct. : 14.5

Calcium per ct. : 0.19

Phosphorus per ct. : 0.07

Nitrogen per ct. : 0.62

Potassium per ct. : 1.22

Material : Rush hay, western (Juncus, spp.)

Total dry matter per ct. : 90.0

Protein per ct. : 9.4

Fat per ct. : 1.8

Fiber per ct. : 29.2

N-free extract per ct. : 44.2

Total minerals per ct. : 5.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.50

Potassium per ct. : —

Material : Russian thistle hay

Total dry matter per ct. : 87.5

Protein per ct. : 8.9

Fat per ct. : 1.6

Fiber per ct. : 26.9

N-free extract per ct. : 37.4

Total minerals per ct. : 12.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.42

Potassium per ct. : —

Material : Rye grass hay, Italian

Total dry matter per ct. : 88.6

Protein per ct. : 8.1

Fat per ct. : 1.9

Fiber per ct. : 27.8

N-free extract per ct. : 43.3

Total minerals per ct. : 7.5

Calcium per ct. : —

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.30

Potassium per ct. : 1.00

Material : Rye grass hay, perennial

Total dry matter per ct. : 88.0

Protein per ct. : 9.2

Fat per ct. : 3.1

Fiber per ct. : 24.2

N-free extract per ct. : 43.4

Total minerals per ct. : 8.1

Calcium per ct. : —

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.47

Potassium per ct. : 1.25

Material : Rye grass hay, native western

Total dry matter per ct. : 87.4

Protein per ct. : 7.8

Fat per ct. : 2.1

Fiber per ct. : 33.5

N-free extract per ct. : 37.6

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.25

Potassium per ct. : —

Material : Rye hay

Total dry matter per ct. : 91.3

Protein per ct. : 6.7

Fat per ct. : 2.1

Fiber per ct. : 36.5

N-free extract per ct. : 41.0

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : 0.18

Nitrogen per ct. : 1.07

Potassium per ct. : 1.05

Material : Rye straw

Total dry matter per ct. : 92.8

Protein per ct. : 3.5

Fat per ct. : 1.2

Fiber per ct. : 38.7

N-free extract per ct. : 45.9

Total minerals per ct. : 3.5

Calcium per ct. : 0.26

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.56

Potassium per ct. : 0.90

Material : Salt bushes, dried

Total dry matter per ct. : 93.5

Protein per ct. : 13.8

Fat per ct. : 1.6

Fiber per ct. : 22.1

N-free extract per ct. : 38.8

Total minerals per ct. : 17.2

Calcium per ct. : 1.88

Phosphorus per ct. : 0.11

Nitrogen per ct. : 2.21

Potassium per ct. : 4.69

Material : Salt grass hay, misc. var.

Total dry matter per ct. : 90.0

Protein per ct. : 8.1

Fat per ct. : 1.8

Fiber per ct. : 28.8

N-free extract per ct. : 39.5

Total minerals per ct. : 11.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.30

Potassium per ct. : —

Material : Sanfoin hay (Onobrychis viciaefolia)

Total dry matter per ct. : 84.1

Protein per ct. : 10.5

Fat per ct. : 2.6

Fiber per ct. : 19.7

N-free extract per ct. : 44.2

Total minerals per ct. : 7.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.68

Potassium per ct. : —

Material : Seaweed, dried (Fucus, spp.)

Total dry matter per ct. : 88.7

Protein per ct. : 5.2

Fat per ct. : 4.2

Fiber per ct. : 9.4

N-free extract per ct. : 53.6

Total minerals per ct. : 16.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.83

Potassium per ct. : —

Material : Seaweed, dried (Laminaria, spp.)

Total dry matter per ct. : 83.7

Protein per ct. : 11.4

Fat per ct. : 1.1

Fiber per ct. : 8.6

N-free extract per ct. : 45.8

Total minerals per ct. : 16.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.82

Potassium per ct. : —

Material : Sedge hay, eastern (Carex, spp.)

Total dry matter per ct. : 90.7

Protein per ct. : 6.1

Fat per ct. : 1.7

Fiber per ct. : 29.2

N-free extract per ct. : 46.3

Total minerals per ct. : 7.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.98

Potassium per ct. : —

Material : Sedge hay, western (Carex, spp.)

Total dry matter per ct. : 90.6

Protein per ct. : 10.1

Fat per ct. : 2.4

Fiber per ct. : 27.3

N-free extract per ct. : 44.0

Total minerals per ct. : 6.8

Calcium per ct. : 0.60

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.62

Potassium per ct. : —

Material : Seradella hay

Total dry matter per ct. : 89.0

Protein per ct. : 16.4

Fat per ct. : 3.2

Fiber per ct. : 29.8

N-free extract per ct. : 32.0

Total minerals per ct. : 7.6

Calcium per ct. : —

Phosphorus per ct. : 0.33

Nitrogen per ct. : 2.62

Potassium per ct. : 1.25

Material : Sorghum bagasse, dried

Total dry matter per ct. : 89.3

Protein per ct. : 3.1

Fat per ct. : 1.4

Fiber per ct. : 31.3

N-free extract per ct. : 50.0

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.50

Potassium per ct. : —

Material : Sorghum fodder, sweet, dry

Total dry matter per ct. : 88.8

Protein per ct. : 6.2

Fat per ct. : 2.4

Fiber per ct. : 25.0

N-free extract per ct. : 48.1

Total minerals per ct. : 7.1

Calcium per ct. : 0.34

Phosphorus per ct. : 0.12

Nitrogen per ct. : 0.99

Potassium per ct. : 1.29

Material : Sorghum fodder, sweet, high in water

Total dry matter per ct. : 65.7

Protein per ct. : 4.5

Fat per ct. : 2.4

Fiber per ct. : 16.6

N-free extract per ct. : 37.6

Total minerals per ct. : 4.6

Calcium per ct. : 0.25

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.72

Potassium per ct. : 0.96

Material : Soybean hay, good, all analyses

Total dry matter per ct. : 88.0

Protein per ct. : 14.4

Fat per ct. : 3.3

Fiber per ct. : 27.5

N-free extract per ct. : 35.8

Total minerals per ct. : 7.0

Calcium per ct. : 0.94

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.30

Potassium per ct. : 0.82

Material : Soybean hay, in bloom or before

Total dry matter per ct. : 88.0

Protein per ct. : 16.7

Fat per ct. : 3.3

Fiber per ct. : 20.6

N-free extract per ct. : 37.8

Total minerals per ct. : 9.6

Calcium per ct. : 1.53

Phosphorus per ct. : 0.27

Nitrogen per ct. : 2.67

Potassium per ct. : 0.86

Material : Soybean hay, seed developing

Total dry matter per ct. : 88.0

Protein per ct. : 14.6

Fat per ct. : 2.4

Fiber per ct. : 27.2

N-free extract per ct. : 36.5

Total minerals per ct. : 7.3

Calcium per ct. : 1.35

Phosphorus per ct. : 0.25

Nitrogen per ct. : 2.34

Potassium per ct. : 0.78

Material : Soybean hay, seed nearly ripe

Total dry matter per ct. : 88.0

Protein per ct. : 15.2

Fat per ct. : 6.6

Fiber per ct. : 24.0

N-free extract per ct. : 38.2

Total minerals per ct. : 4.0

Calcium per ct. : 0.86

Phosphorus per ct. : 0.32

Nitrogen per ct. : 2.43

Potassium per ct. : 0.81

Material : Soybean hay, poor quality, weathered

Total dry matter per ct. : 89.0

Protein per ct. : 9.2

Fat per ct. : 1.2

Fiber per ct. : 41.0

N-free extract per ct. : 30.4

Total minerals per ct. : 7.2

Calcium per ct. : 0.94

Phosphorus per ct. : —

Nitrogen per ct. : 1.47

Potassium per ct. : —

Material : Soybean straw

Total dry matter per ct. : 88.8

Protein per ct. : 4.0

Fat per ct. : 1.1

Fiber per ct. : 41.1

N-free extract per ct. : 37.5

Total minerals per ct. : 5.1

Calcium per ct. : —

Phosphorus per ct. : 0.13

Nitrogen per ct. : 0.64

Potassium per ct. : 0.62

Material : Soybean and Sudan grass hay, chiefly Sudan

Total dry matter per ct. : 89.0

Protein per ct. : 7.4

Fat per ct. : 2.2

Fiber per ct. : 31.1

N-free extract per ct. : 43.4

Total minerals per ct. : 4.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.18

Potassium per ct. : —

Material : Spanish moss, dried

Total dry matter per ct. : 89.2

Protein per ct. : 5.0

Fat per ct. : 2.4

Fiber per ct. : 26.6

N-free extract per ct. : 47.7

Total minerals per ct. : 7.5

Calcium per ct. : —

Phosphorus per ct. : 0.04

Nitrogen per ct. : 0.80

Potassium per ct. : 0.46

Material : Sudan grass hay, all analyses

Total dry matter per ct. : 89.3

Protein per ct. : 8.8

Fat per ct. : 1.6

Fiber per ct. : 27.9

N-free extract per ct. : 42.9

Total minerals per ct. : 8.1

Calcium per ct. : 0.36

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.41

Potassium per ct. : 1.30

Material : Sudan grass hay, before bloom

Total dry matter per ct. : 89.6

Protein per ct. : 11.2

Fat per ct. : 1.5

Fiber per ct. : 26.1

N-free extract per ct. : 41.3

Total minerals per ct. : 9.5

Calcium per ct. : 0.41

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.79

Potassium per ct. : —

Material : Sudan grass hay, in bloom

Total dry matter per ct. : 89.2

Protein per ct. : 8.4

Fat per ct. : 1.5

Fiber per ct. : 30.7

N-free extract per ct. : 41.8

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.34

Potassium per ct. : —

Material : Sudan grass hay, in seed

Total dry matter per ct. : 89.5

Protein per ct. : 6.8

Fat per ct. : 1.6

Fiber per ct. : 29.9

N-free extract per ct. : 44.4

Total minerals per ct. : 6.8

Calcium per ct. : 0.27

Phosphorus per ct. : 0.19

Nitrogen per ct. : 1.09

Potassium per ct. : —

Material : Sudan grass, young, dehydrated

Total dry matter per ct. : 88.0

Protein per ct. : 14.5

Fat per ct. : 2.5

Fiber per ct. : 20.4

N-free extract per ct. : 41.2

Total minerals per ct. : 9.4

Calcium per ct. : 0.52

Phosphorus per ct. : 0.39

Nitrogen per ct. : 2.32

Potassium per ct. : —

Material : Sudan grass straw

Total dry matter per ct. : 90.4

Protein per ct. : 7.1

Fat per ct. : 1.5

Fiber per ct. : 33.0

N-free extract per ct. : 42.3

Total minerals per ct. : 6.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.14

Potassium per ct. : —

Material : Sugar cane fodder, Japanese, dried

Total dry matter per ct. : 89.0

Protein per ct. : 1.3

Fat per ct. : 1.8

Fiber per ct. : 19.7

N-free extract per ct. : 64.3

Total minerals per ct. : 1.9

Calcium per ct. : 0.32

Phosphorus per ct. : 0.14

Nitrogen per ct. : 0.21

Potassium per ct. : 0.58

Material : Sugar cane bagasse, dried

Total dry matter per ct. : 95.5

Protein per ct. : 1.1

Fat per ct. : 0.4

Fiber per ct. : 49.6

N-free extract per ct. : 42.0

Total minerals per ct. : 2.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.18

Potassium per ct. : —

Material : Sugar cane pulp, dried

Total dry matter per ct. : 93.8

Protein per ct. : 1.7

Fat per ct. : 0.6

Fiber per ct. : 45.6

N-free extract per ct. : 42.2

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.27

Potassium per ct. : —

Material : Sweet potato vine, dried

Total dry matter per ct. : 90.7

Protein per ct. : 12.6

Fat per ct. : 3.3

Fiber per ct. : 19.1

N-free extract per ct. : 45.5

Total minerals per ct. : 10.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.02

Potassium per ct. : —

Material : Teosinte fodder, dried

Total dry matter per ct. : 89.4

Protein per ct. : 9.1

Fat per ct. : 1.9

Fiber per ct. : 26.5

N-free extract per ct. : 41.7

Total minerals per ct. : 10.3

Calcium per ct. : —

Phosphorus per ct. : 0.17

Nitrogen per ct. : 1.46

Potassium per ct. : 0.88

Material : Timothy hay, all analyses

Total dry matter per ct. : 89.0

Protein per ct. : 6.5

Fat per ct. : 2.4

Fiber per ct. : 30.2

N-free extract per ct. : 45.0

Total minerals per ct. : 4.9

Calcium per ct. : 0.23

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.04

Potassium per ct. : 1.50

Material : Timothy hay, before bloom

Total dry matter per ct. : 89.0

Protein per ct. : 9.7

Fat per ct. : 2.7

Fiber per ct. : 27.4

N-free extract per ct. : 42.7

Total minerals per ct. : 6.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.55

Potassium per ct. : —

Material : Timothy, full bloom

Total dry matter per ct. : 89.0

Protein per ct. : 6.4

Fat per ct. : 2.5

Fiber per ct. : 30.4

N-free extract per ct. : 44.8

Total minerals per ct. : 4.9

Calcium per ct. : 0.23

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.02

Potassium per ct. : 1.50

Material : Timothy hay, in bloom, nitrogen fertilized

Total dry matter per ct. : 89.0

Protein per ct. : 9.7

Fat per ct. : 2.1

Fiber per ct. : 31.6

N-free extract per ct. : 42.6

Total minerals per ct. : 3.9

Calcium per ct. : 0.40

Phosphorus per ct. : 0.21

Nitrogen per ct. : 1.41

Potassium per ct. : 1.41

Material : Timothy hay, late seed

Total dry matter per ct. : 89.0

Protein per ct. : 5.3

Fat per ct. : 2.3

Fiber per ct. : 31.0

N-free extract per ct. : 45.9

Total minerals per ct. : 4.5

Calcium per ct. : 0.14

Phosphorus per ct. : 0.15

Nitrogen per ct. : 0.85

Potassium per ct. : 1.41

Material : Timothy hay, in bloom, dehydrated

Total dry matter per ct. : 89.0

Protein per ct. : 7.7

Fat per ct. : 2.3

Fiber per ct. : 28.3

N-free extract per ct. : 45.5

Total minerals per ct. : 5.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.23

Potassium per ct. : —

Material : Timothy hay, second cutting

Total dry matter per ct. : 88.7

Protein per ct. : 15.0

Fat per ct. : 4.6

Fiber per ct. : 25.4

N-free extract per ct. : 36.5

Total minerals per ct. : 7.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.40

Potassium per ct. : —

Material : Timothy and clover hay, one-fourth clover

Total dry matter per ct. : 88.8

Protein per ct. : 7.8

Fat per ct. : 2.4

Fiber per ct. : 29.5

N-free extract per ct. : 43.8

Total minerals per ct. : 5.3

Calcium per ct. : 0.51

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.25

Potassium per ct. : 1.48

Material : Velvet bean hay

Total dry matter per ct. : 92.8

Protein per ct. : 16.4

Fat per ct. : 3.1

Fiber per ct. : 27.5

N-free extract per ct. : 38.4

Total minerals per ct. : 7.4

Calcium per ct. : —

Phosphorus per ct. : 0.24

Nitrogen per ct. : 2.62

Potassium per ct. : 2.20

Material : Vetch hay, common

Total dry matter per ct. : 89.0

Protein per ct. : 13.3

Fat per ct. : 1.1

Fiber per ct. : 25.2

N-free extract per ct. : 32.2

Total minerals per ct. : 6.2

Calcium per ct. : 1.18

Phosphorus per ct. : 0.32

Nitrogen per ct. : 2.13

Potassium per ct. : 2.22

Material : Vetch hay, hairy

Total dry matter per ct. : 88.0

Protein per ct. : 19.3

Fat per ct. : 2.6

Fiber per ct. : 24.5

N-free extract per ct. : 33.1

Total minerals per ct. : 8.5

Calcium per ct. : 1.13

Phosphorus per ct. : 0.32

Nitrogen per ct. : 3.09

Potassium per ct. : 1.96

Material : Vetch-and-oat hay, over half vetch

Total dry matter per ct. : 87.6

Protein per ct. : 11.9

Fat per ct. : 2.7

Fiber per ct. : 27.3

N-free extract per ct. : 37.5

Total minerals per ct. : 8.2

Calcium per ct. : 0.76

Phosphorus per ct. : 0.27

Nitrogen per ct. : 1.90

Potassium per ct. : 1.51

Material : Vetch-and-wheat hay, cut early

Total dry matter per ct. : 90.0

Protein per ct. : 15.4

Fat per ct. : 2.2

Fiber per ct. : 28.8

N-free extract per ct. : 36.4

Total minerals per ct. : 7.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.46

Potassium per ct. : —

Material : Wheat chaff

Total dry matter per ct. : 90.0

Protein per ct. : 4.4

Fat per ct. : 1.5

Fiber per ct. : 29.4

N-free extract per ct. : 47.1

Total minerals per ct. : 7.6

Calcium per ct. : 0.21

Phosphorus per ct. : 0.14

Nitrogen per ct. : 0.70

Potassium per ct. : 0.50

Material : Wheat hay

Total dry matter per ct. : 90.4

Protein per ct. : 6.1

Fat per ct. : 1.8

Fiber per ct. : 26.1

N-free extract per ct. : 50.0

Total minerals per ct. : 6.4

Calcium per ct. : 0.14

Phosphorus per ct. : 0.18

Nitrogen per ct. : 0.98

Potassium per ct. : 1.47

Material : Wheat straw

Total dry matter per ct. : 92.5

Protein per ct. : 3.9

Fat per ct. : 1.5

Fiber per ct. : 36.9

N-free extract per ct. : 41.9

Total minerals per ct. : 8.3

Calcium per ct. : 0.21

Phosphorus per ct. : 0.07

Nitrogen per ct. : 0.62

Potassium per ct. : 0.79

Material : Wheat grass hay, crested, cut early

Total dry matter per ct. : 90.0

Protein per ct. : 9.2

Fat per ct. : 2.0

Fiber per ct. : 32.2

N-free extract per ct. : 40.2

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.47

Potassium per ct. : —

Material : Wheat grass hay, slender

Total dry matter per ct. : 90.0

Protein per ct. : 8.0

Fat per ct. : 2.1

Fiber per ct. : 32.2

N-free extract per ct. : 41.0

Total minerals per ct. : 6.7

Calcium per ct. : 0.30

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.28

Potassium per ct. : 2.41

Material : Winter fat, or white sage, dried (Eurotia lanata)

Total dry matter per ct. : 92.6

Protein per ct. : 12.9

Fat per ct. : 1.9

Fiber per ct. : 27.4

N-free extract per ct. : 40.8

Total minerals per ct. : 9.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.06

Potassium per ct. : —

Material : Wire grass hay, southern (Aristida, spp.)

Total dry matter per ct. : 90.0

Protein per ct. : 5.5

Fat per ct. : 1.4

Fiber per ct. : 31.8

N-free extract per ct. : 47.9

Total minerals per ct. : 3.4

Calcium per ct. : 0.15

Phosphorus per ct. : 0.14

Nitrogen per ct. : 0.88

Potassium per ct. : —

Material : Wire grass hay, western (Aristida, spp.)

Total dry matter per ct. : 90.0

Protein per ct. : 6.4

Fat per ct. : 1.3

Fiber per ct. : 34.1

N-free extract per ct. : 41.0

Total minerals per ct. : 7.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.02

Potassium per ct. : —

Material : Yucca, or beargrass, dried

Total dry matter per ct. : 92.6

Protein per ct. : 6.6

Fat per ct. : 2.2

Fiber per ct. : 38.6

N-free extract per ct. : 38.3

Total minerals per ct. : 6.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.06

Potassium per ct. : —

CONCENTRATES

Material : Acorns, whole (red oak)

Total dry matter per ct. : 50.0

Protein per ct. : 3.2

Fat per ct. : 10.7

Fiber per ct. : 9.9

N-free extract per ct. : 25.0

Total minerals per ct. : 1.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.51

Potassium per ct. : —

Material : Acorns, whole (white and post oaks)

Total dry matter per ct. : 50.0

Protein per ct. : 2.7

Fat per ct. : 3.0

Fiber per ct. : 9.3

N-free extract per ct. : 33.7

Total minerals per ct. : 1.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.43

Potassium per ct. : —

Material : Alfalfa-molasses feed

Total dry matter per ct. : 86.0

Protein per ct. : 11.4

Fat per ct. : 1.2

Fiber per ct. : 18.5

N-free extract per ct. : 46.2

Total minerals per ct. : 8.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.82

Potassium per ct. : —

Material : Alfalfa seed

Total dry matter per ct. : 88.3

Protein per ct. : 33.2

Fat per ct. : 10.6

Fiber per ct. : 8.1

N-free extract per ct. : 32.0

Total minerals per ct. : 4.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.31

Potassium per ct. : —

Material : Alfalfa seed screenings

Total dry matter per ct. : 90.3

Protein per ct. : 31.1

Fat per ct. : 9.9

Fiber per ct. : 11.1

N-free extract per ct. : 33.1

Total minerals per ct. : 5.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.98

Potassium per ct. : —

Material : Apple-pectin pulp, dried

Total dry matter per ct. : 91.2

Protein per ct. : 7.0

Fat per ct. : 7.3

Fiber per ct. : 24.2

N-free extract per ct. : 49.4

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.12

Potassium per ct. : —

Material : Apple-pectin pulp, wet

Total dry matter per ct. : 16.7

Protein per ct. : 1.5

Fat per ct. : 0.9

Fiber per ct. : 5.8

N-free extract per ct. : 7.9

Total minerals per ct. : 0.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.24

Potassium per ct. : —

Material : Apple pomace, dried

Total dry matter per ct. : 89.4

Protein per ct. : 4.5

Fat per ct. : 5.0

Fiber per ct. : 15.6

N-free extract per ct. : 62.1

Total minerals per ct. : 2.2

Calcium per ct. : 0.10

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.72

Potassium per ct. : 0.43

Material : Apple pomace, wet

Total dry matter per ct. : 21.1

Protein per ct. : 1.3

Fat per ct. : 1.3

Fiber per ct. : 3.7

N-free extract per ct. : 13.9

Total minerals per ct. : 0.9

Calcium per ct. : 0.02

Phosphorus per ct. : 0.02

Nitrogen per ct. : 0.21

Potassium per ct. : 0.10

Material : Atlas sorghum grain

Total dry matter per ct. : 89.1

Protein per ct. : 11.3

Fat per ct. : 3.3

Fiber per ct. : 2.0

N-free extract per ct. : 70.6

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.81

Potassium per ct. : —

Material : Atlas sorghum head chops

Total dry matter per ct. : 88.0

Protein per ct. : 9.5

Fat per ct. : 2.8

Fiber per ct. : 10.7

N-free extract per ct. : 60.2

Total minerals per ct. : 4.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.52

Potassium per ct. : —

Material : Avocado oil meal

Total dry matter per ct. : 91.4

Protein per ct. : 18.6

Fat per ct. : 1.1

Fiber per ct. : 17.6

N-free extract per ct. : 36.0

Total minerals per ct. : 18.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.98

Potassium per ct. : —

Material : Babassu oil meal

Total dry matter per ct. : 92.8

Protein per ct. : 24.2

Fat per ct. : 6.8

Fiber per ct. : 12.0

N-free extract per ct. : 44.6

Total minerals per ct. : 5.2

Calcium per ct. : 0.13

Phosphorus per ct. : 0.71

Nitrogen per ct. : 3.87

Potassium per ct. : —

Material : Bakery waste, dried (high in fat)

Total dry matter per ct. : 91.6

Protein per ct. : 10.9

Fat per ct. : 13.7

Fiber per ct. : 0.7

N-free extract per ct. : 64.7

Total minerals per ct. : 1.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.74

Potassium per ct. : —

Material : Barley, common, not including Pacific Coast states

Total dry matter per ct. : 89.4

Protein per ct. : 12.7

Fat per ct. : 1.9

Fiber per ct. : 5.4

N-free extract per ct. : 66.6

Total minerals per ct. : 2.8

Calcium per ct. : 0.06

Phosphorus per ct. : 0.37

Nitrogen per ct. : 2.03

Potassium per ct. : 0.49

Material : Barley, Pacific Coast states

Total dry matter per ct. : 89.8

Protein per ct. : 8.7

Fat per ct. : 1.9

Fiber per ct. : 5.7

N-free extract per ct. : 70.9

Total minerals per ct. : 2.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.39

Potassium per ct. : —

Material : Barley, light weight

Total dry matter per ct. : 89.1

Protein per ct. : 12.1

Fat per ct. : 2.1

Fiber per ct. : 7.4

N-free extract per ct. : 64.3

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.94

Potassium per ct. : —

Material : Barley, hull-less, or bald

Total dry matter per ct. : 90.2

Protein per ct. : 11.6

Fat per ct. : 2.0

Fiber per ct. : 2.4

N-free extract per ct. : 72.1

Total minerals per ct. : 2.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.86

Potassium per ct. : —

Material : Barley feed, high grade

Total dry matter per ct. : 90.3

Protein per ct. : 13.5

Fat per ct. : 3.5

Fiber per ct. : 8.7

N-free extract per ct. : 60.5

Total minerals per ct. : 4.1

Calcium per ct. : 0.03

Phosphorus per ct. : 0.40

Nitrogen per ct. : 2.16

Potassium per ct. : 0.60

Material : Barley feed, low grade

Total dry matter per ct. : 92.0

Protein per ct. : 12.3

Fat per ct. : 3.45

Fiber per ct. : 14.7

N-free extract per ct. : 56.2

Total minerals per ct. : 5.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.97

Potassium per ct. : —

Material : Barley, malted

Total dry matter per ct. : 93.4

Protein per ct. : 12.7

Fat per ct. : 2.1

Fiber per ct. : 5.4

N-free extract per ct. : 70.9

Total minerals per ct. : 2.3

Calcium per ct. : 0.06

Phosphorus per ct. : 0.42

Nitrogen per ct. : 2.03

Potassium per ct. : 0.37

Material : Barley screenings

Total dry matter per ct. : 88.6

Protein per ct. : 11.6

Fat per ct. : 2.7

Fiber per ct. : 9.1

N-free extract per ct. : 61.3

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.86

Potassium per ct. : —

Material : Beans, field, or navy

Total dry matter per ct. : 90.0

Protein per ct. : 22.9

Fat per ct. : 1.4

Fiber per ct. : 4.2

N-free extract per ct. : 57.3

Total minerals per ct. : 4.2

Calcium per ct. : 0.15

Phosphorus per ct. : 0.57

Nitrogen per ct. : 3.66

Potassium per ct. : 1.27

Material : Beans, kidney

Total dry matter per ct. : 89.0

Protein per ct. : 23.0

Fat per ct. : 1.2

Fiber per ct. : 4.1

N-free extract per ct. : 56.8

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.68

Potassium per ct. : —

Material : Beans, lima

Total dry matter per ct. : 89.7

Protein per ct. : 21.2

Fat per ct. : 1.1

Fiber per ct. : 4.7

N-free extract per ct. : 58.2

Total minerals per ct. : 4.5

Calcium per ct. : 0.09

Phosphorus per ct. : 0.37

Nitrogen per ct. : 3.39

Potassium per ct. : 1.70

Material : Beans, mung

Total dry matter per ct. : 90.2

Protein per ct. : 23.3

Fat per ct. : 1.0

Fiber per ct. : 3.5

N-free extract per ct. : 58.5

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.73

Potassium per ct. : —

Material : Beans, pinto

Total dry matter per ct. : 89.9

Protein per ct. : 22.5

Fat per ct. : 1.2

Fiber per ct. : 4.1

N-free extract per ct. : 57.7

Total minerals per ct. : 4.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.60

Potassium per ct. : —

Material : Beans, tepary

Total dry matter per ct. : 90.5

Protein per ct. : 22.2

Fat per ct. : 1.4

Fiber per ct. : 3.4

N-free extract per ct. : 59.3

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.56

Potassium per ct. : —

Material : Beechnuts

Total dry matter per ct. : 91.4

Protein per ct. : 15.0

Fat per ct. : 30.6

Fiber per ct. : 15.0

N-free extract per ct. : 27.5

Total minerals per ct. : 3.3

Calcium per ct. : 0.58

Phosphorus per ct. : 0.30

Nitrogen per ct. : 2.40

Potassium per ct. : 0.62

Material : Beef scraps

Total dry matter per ct. : 94.5

Protein per ct. : 55.6

Fat per ct. : 10.9

Fiber per ct. : 1.2

N-free extract per ct. : 0.5

Total minerals per ct. : 26.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 8.90

Potassium per ct. : —

Material : Beet pulp, dried

Total dry matter per ct. : 90.1

Protein per ct. : 9.2

Fat per ct. : 0.5

Fiber per ct. : 19.8

N-free extract per ct. : 57.2

Total minerals per ct. : 3.4

Calcium per ct. : 0.67

Phosphorus per ct. : 0.08

Nitrogen per ct. : 1.47

Potassium per ct. : 0.18

Material : Beet pulp, molasses, dried

Total dry matter per ct. : 91.9

Protein per ct. : 10.7

Fat per ct. : 0.7

Fiber per ct. : 16.0

N-free extract per ct. : 59.4

Total minerals per ct. : 5.1

Calcium per ct. : 0.62

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.71

Potassium per ct. : 1.63

Material : Beet pulp, wet

Total dry matter per ct. : 11.6

Protein per ct. : 1.5

Fat per ct. : 0.3

Fiber per ct. : 4.0

N-free extract per ct. : 5.3

Total minerals per ct. : 0.5

Calcium per ct. : 0.09

Phosphorus per ct. : 0.01

Nitrogen per ct. : 0.24

Potassium per ct. : 0.02

Material : Beet pulp, wet, pressed

Total dry matter per ct. : 14.2

Protein per ct. : 1.4

Fat per ct. : 0.4

Fiber per ct. : 4.6

N-free extract per ct. : 7.1

Total minerals per ct. : 0.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.22

Potassium per ct. : —

Material : Blood flour, or soluble blood meal

Total dry matter per ct. : 92.2

Protein per ct. : 84.7

Fat per ct. : 1.0

Fiber per ct. : 1.1

N-free extract per ct. : 0.7

Total minerals per ct. : 4.7

Calcium per ct. : 0.68

Phosphorus per ct. : 0.50

Nitrogen per ct. : 13.55

Potassium per ct. : —

Material : Blood meal

Total dry matter per ct. : 91.8

Protein per ct. : 84.5

Fat per ct. : 1.1

Fiber per ct. : 1.0

N-free extract per ct. : 0.7

Total minerals per ct. : 4.5

Calcium per ct. : 0.33

Phosphorus per ct. : 0.25

Nitrogen per ct. : 13.52

Potassium per ct. : 0.09

Material : Bone meal, raw

Total dry matter per ct. : 93.6

Protein per ct. : 26.0

Fat per ct. : 5.0

Fiber per ct. : 1.0

N-free extract per ct. : 2.5

Total minerals per ct. : 59.1

Calcium per ct. : 23.05

Phosphorus per ct. : 10.22

Nitrogen per ct. : 4.16

Potassium per ct. : —

Material : Bone meal, raw, solvent process

Total dry matter per ct. : 93.1

Protein per ct. : 25.7

Fat per ct. : 1.0

Fiber per ct. : 1.0

N-free extract per ct. : 1.9

Total minerals per ct. : 63.5

Calcium per ct. : 24.02

Phosphorus per ct. : 10.65

Nitrogen per ct. : 4.11

Potassium per ct. : —

Material : Bone meal, steamed

Total dry matter per ct. : 96.3

Protein per ct. : 7.1

Fat per ct. : 3.3

Fiber per ct. : 0.8

N-free extract per ct. : 3.8

Total minerals per ct. : 81.3

Calcium per ct. : 31.74

Phosphorus per ct. : 15.00

Nitrogen per ct. : 1.14

Potassium per ct. : 0.18

Material : Bone meal, steamed, solvent process

Total dry matter per ct. : 96.8

Protein per ct. : 7.2

Fat per ct. : 0.4

Fiber per ct. : 1.5

N-free extract per ct. : 3.7

Total minerals per ct. : 84.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.15

Potassium per ct. : —

Material : Bone meal, steamed, special

Total dry matter per ct. : 97.7

Protein per ct. : 13.5

Fat per ct. : 7.9

Fiber per ct. : 1.0

N-free extract per ct. : 5.1

Total minerals per ct. : 70.2

Calcium per ct. : 31.88

Phosphorus per ct. : 13.48

Nitrogen per ct. : 2.16

Potassium per ct. : —

Material : Bone meal, 10 to 20% protein

Total dry matter per ct. : 97.2

Protein per ct. : 14.6

Fat per ct. : 6.5

Fiber per ct. : 1.5

N-free extract per ct. : 3.6

Total minerals per ct. : 71.0

Calcium per ct. : 26.00

Phosphorus per ct. : 12.66

Nitrogen per ct. : 2.34

Potassium per ct. : —

Material : Bread, white, enriched

Total dry matter per ct. : 64.1

Protein per ct. : 8.5

Fat per ct. : 2.0

Fiber per ct. : 0.3

N-free extract per ct. : 52.0

Total minerals per ct. : 1.3

Calcium per ct. : 0.06

Phosphorus per ct. : 0.10

Nitrogen per ct. : 1.36

Potassium per ct. : 0.10

Material : Brewers’ grains, dried, 25% protein or over

Total dry matter per ct. : 92.9

Protein per ct. : 27.6

Fat per ct. : 6.5

Fiber per ct. : 14.3

N-free extract per ct. : 40.9

Total minerals per ct. : 3.6

Calcium per ct. : 0.29

Phosphorus per ct. : 0.48

Nitrogen per ct. : 4.42

Potassium per ct. : 0.10

Material : Brewers’ grains, dried, below 25% protein

Total dry matter per ct. : 92.3

Protein per ct. : 23.4

Fat per ct. : 6.4

Fiber per ct. : 16.1

N-free extract per ct. : 42.5

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.74

Potassium per ct. : —

Material : Brewers’ grains, dried, from California barley

Total dry matter per ct. : 91.1

Protein per ct. : 20.0

Fat per ct. : 5.7

Fiber per ct. : 18.1

N-free extract per ct. : 43.6

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.20

Potassium per ct. : —

Material : Brewers’ grains, wet

Total dry matter per ct. : 23.7

Protein per ct. : 5.7

Fat per ct. : 1.6

Fiber per ct. : 3.6

N-free extract per ct. : 11.8

Total minerals per ct. : 1.0

Calcium per ct. : 0.07

Phosphorus per ct. : 0.12

Nitrogen per ct. : 0.91

Potassium per ct. : 0.02

Material : Broom corn seed

Total dry matter per ct. : 89.7

Protein per ct. : 9.2

Fat per ct. : 3.7

Fiber per ct. : 5.1

N-free extract per ct. : 69.1

Total minerals per ct. : 2.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.47

Potassium per ct. : —

Material : Buckwheat, ordinary varieties

Total dry matter per ct. : 88.0

Protein per ct. : 10.3

Fat per ct. : 2.3

Fiber per ct. : 10.7

N-free extract per ct. : 62.8

Total minerals per ct. : 1.9

Calcium per ct. : 0.09

Phosphorus per ct. : 0.31

Nitrogen per ct. : 1.64

Potassium per ct. : 0.45

Material : Buckwheat, Tartary

Total dry matter per ct. : 88.1

Protein per ct. : 10.1

Fat per ct. : 2.4

Fiber per ct. : 12.7

N-free extract per ct. : 60.9

Total minerals per ct. : 2.0

Calcium per ct. : 0.13

Phosphorus per ct. : 0.31

Nitrogen per ct. : 1.62

Potassium per ct. : 0.44

Material : Buckwheat feed, good grade

Total dry matter per ct. : 89.3

Protein per ct. : 18.5

Fat per ct. : 4.9

Fiber per ct. : 18.2

N-free extract per ct. : 43.5

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : 0.48

Nitrogen per ct. : 2.96

Potassium per ct. : 0.66

Material : Buckwheat feed, low grade

Total dry matter per ct. : 88.3

Protein per ct. : 13.3

Fat per ct. : 3.4

Fiber per ct. : 28.6

N-free extract per ct. : 39.8

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : 0.37

Nitrogen per ct. : 2.13

Potassium per ct. : 0.68

Material : Buckwheat flour

Total dry matter per ct. : 88.1

Protein per ct. : 10.2

Fat per ct. : 2.1

Fiber per ct. : 0.9

N-free extract per ct. : 73.4

Total minerals per ct. : 1.5

Calcium per ct. : 0.01

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.63

Potassium per ct. : 0.16

Material : Buckwheat kernels, without hulls

Total dry matter per ct. : 88.0

Protein per ct. : 14.1

Fat per ct. : 3.4

Fiber per ct. : 1.8

N-free extract per ct. : 66.5

Total minerals per ct. : 2.2

Calcium per ct. : 0.05

Phosphorus per ct. : 0.45

Nitrogen per ct. : 2.26

Potassium per ct. : 0.49

Material : Buckwheat middlings

Total dry matter per ct. : 88.7

Protein per ct. : 29.7

Fat per ct. : 7.3

Fiber per ct. : 7.4

N-free extract per ct. : 39.4

Total minerals per ct. : 4.9

Calcium per ct. : —

Phosphorus per ct. : 1.02

Nitrogen per ct. : 4.76

Potassium per ct. : 0.98

Material : Buttermilk

Total dry matter per ct. : 9.4

Protein per ct. : 3.5

Fat per ct. : 0.6

Fiber per ct. : 0

N-free extract per ct. : 4.5

Total minerals per ct. : 0.8

Calcium per ct. : 0.14

Phosphorus per ct. : 0.08

Nitrogen per ct. : 0.56

Potassium per ct. : 0.07

Material : Buttermilk, condensed

Total dry matter per ct. : 29.7

Protein per ct. : 10.9

Fat per ct. : 2.2

Fiber per ct. : 0

N-free extract per ct. : 12.6

Total minerals per ct. : 4.0

Calcium per ct. : 0.44

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.74

Potassium per ct. : 0.23

Material : Buttermilk, dried

Total dry matter per ct. : 92.4

Protein per ct. : 32.4

Fat per ct. : 6.4

Fiber per ct. : 0.3

N-free extract per ct. : 43.3

Total minerals per ct. : 10.0

Calcium per ct. : 1.36

Phosphorus per ct. : 0.82

Nitrogen per ct. : 5.18

Potassium per ct. : 0.71

Material : Carob bean and pods

Total dry matter per ct. : 87.8

Protein per ct. : 5.5

Fat per ct. : 2.6

Fiber per ct. : 8.7

N-free extract per ct. : 68.5

Total minerals per ct. : 2.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.88

Potassium per ct. : —

Material : Carob bean pods

Total dry matter per ct. : 89.5

Protein per ct. : 4.7

Fat per ct. : 2.5

Fiber per ct. : 8.7

N-free extract per ct. : 70.9

Total minerals per ct. : 2.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.75

Potassium per ct. : —

Material : Carob bean seeds

Total dry matter per ct. : 88.5

Protein per ct. : 16.7

Fat per ct. : 2.6

Fiber per ct. : 7.6

N-free extract per ct. : 58.4

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.67

Potassium per ct. : —

Material : Cassava roots, dried

Total dry matter per ct. : 94.4

Protein per ct. : 2.8

Fat per ct. : 0.5

Fiber per ct. : 5.0

N-free extract per ct. : 84.1

Total minerals per ct. : 2.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.45

Potassium per ct. : —

Material : Cassava meal (starch waste)

Total dry matter per ct. : 86.8

Protein per ct. : 0.9

Fat per ct. : 0.7

Fiber per ct. : 4.6

N-free extract per ct. : 78.8

Total minerals per ct. : 1.8

Calcium per ct. : —

Phosphorus per ct. : 0.03

Nitrogen per ct. : 0.14

Potassium per ct. : 0.23

Material : Cheese rind, or cheese meal

Total dry matter per ct. : 91.0

Protein per ct. : 59.5

Fat per ct. : 8.9

Fiber per ct. : 0.4

N-free extract per ct. : 10.7

Total minerals per ct. : 11.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 9.52

Potassium per ct. : —

Material : Chess, or cheat, seed

Total dry matter per ct. : 89.6

Protein per ct. : 9.7

Fat per ct. : 1.7

Fiber per ct. : 8.2

N-free extract per ct. : 66.4

Total minerals per ct. : 3.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.56

Potassium per ct. : —

Material : Chick peas

Total dry matter per ct. : 90.0

Protein per ct. : 20.3

Fat per ct. : 4.3

Fiber per ct. : 8.5

N-free extract per ct. : 54.0

Total minerals per ct. : 2.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.24

Potassium per ct. : —

Material : Citrus pulp, dried

Total dry matter per ct. : 90.1

Protein per ct. : 5.9

Fat per ct. : 3.1

Fiber per ct. : 11.5

N-free extract per ct. : 62.7

Total minerals per ct. : 6.9

Calcium per ct. : 2.07

Phosphorus per ct. : 0.15

Nitrogen per ct. : 0.94

Potassium per ct. : —

Material : Citrus pulp and molasses, dried

Total dry matter per ct. : 92.0

Protein per ct. : 5.3

Fat per ct. : 2.8

Fiber per ct. : 9.3

N-free extract per ct. : 66.6

Total minerals per ct. : 8.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.84

Potassium per ct. : —

Material : Citrus pulp, wet

Total dry matter per ct. : 18.3

Protein per ct. : 1.2

Fat per ct. : 0.6

Fiber per ct. : 2.3

N-free extract per ct. : 12.8

Total minerals per ct. : 1.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.19

Potassium per ct. : —

Material : Clover seed, red

Total dry matter per ct. : 87.5

Protein per ct. : 32.6

Fat per ct. : 7.8

Fiber per ct. : 9.2

N-free extract per ct. : 31.2

Total minerals per ct. : 6.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.22

Potassium per ct. : —

Material : Clover seed screenings, red

Total dry matter per ct. : 90.5

Protein per ct. : 28.2

Fat per ct. : 5.9

Fiber per ct. : 10.2

N-free extract per ct. : 40.3

Total minerals per ct. : 5.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.51

Potassium per ct. : —

Material : Clover seed screenings, sweet

Total dry matter per ct. : 90.1

Protein per ct. : 21.7

Fat per ct. : 3.7

Fiber per ct. : 14.7

N-free extract per ct. : 41.1

Total minerals per ct. : 8.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.47

Potassium per ct. : —

Material : Cocoa meal

Total dry matter per ct. : 96.0

Protein per ct. : 24.3

Fat per ct. : 17.1

Fiber per ct. : 5.1

N-free extract per ct. : 43.7

Total minerals per ct. : 5.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.89

Potassium per ct. : —

Material : Cocoa shells

Total dry matter per ct. : 95.1

Protein per ct. : 15.4

Fat per ct. : 3.0

Fiber per ct. : 16.5

N-free extract per ct. : 49.9

Total minerals per ct. : 10.3

Calcium per ct. : —

Phosphorus per ct. : 0.59

Nitrogen per ct. : 2.46

Potassium per ct. : 2.16

Material : Coconut oil meal, hydr. or exp. process

Total dry matter per ct. : 93.2

Protein per ct. : 21.3

Fat per ct. : 6.7

Fiber per ct. : 10.7

N-free extract per ct. : 48.3

Total minerals per ct. : 6.2

Calcium per ct. : 0.21

Phosphorus per ct. : 0.64

Nitrogen per ct. : 3.41

Potassium per ct. : 1.95

Material : Coconut oil meal, high in fat

Total dry matter per ct. : 93.7

Protein per ct. : 21.0

Fat per ct. : 10.6

Fiber per ct. : 11.3

N-free extract per ct. : 44.4

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.36

Potassium per ct. : —

Material : Coconut oil meal, solvent process

Total dry matter per ct. : 91.1

Protein per ct. : 21.4

Fat per ct. : 2.4

Fiber per ct. : 13.3

N-free extract per ct. : 47.4

Total minerals per ct. : 6.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.42

Potassium per ct. : —

Material : Cod-liver oil meal

Total dry matter per ct. : 92.5

Protein per ct. : 50.4

Fat per ct. : 28.9

Fiber per ct. : 0.7

N-free extract per ct. : 9.6

Total minerals per ct. : 2.9

Calcium per ct. : 0.18

Phosphorus per ct. : 0.61

Nitrogen per ct. : 8.06

Potassium per ct. : —

Material : Corn, dent, Grade No. 1

Total dry matter per ct. : 87.0

Protein per ct. : 8.8

Fat per ct. : 4.0

Fiber per ct. : 2.1

N-free extract per ct. : 70.9

Total minerals per ct. : 1.2

Calcium per ct. : 0.02

Phosphorus per ct. : 0.28

Nitrogen per ct. : 1.41

Potassium per ct. : 0.28

Material : Corn, dent, Grade No. 2

Total dry matter per ct. : 85.0

Protein per ct. : 8.6

Fat per ct. : 3.9

Fiber per ct. : 2.0

N-free extract per ct. : 69.3

Total minerals per ct. : 1.2

Calcium per ct. : 0.02

Phosphorus per ct. : 0.27

Nitrogen per ct. : 1.38

Potassium per ct. : 0.27

Material : Corn, dent, Grade No. 3

Total dry matter per ct. : 83.5

Protein per ct. : 8.4

Fat per ct. : 3.8

Fiber per ct. : 2.0

N-free extract per ct. : 68.1

Total minerals per ct. : 1.2

Calcium per ct. : 0.02

Phosphorus per ct. : 0.27

Nitrogen per ct. : 1.34

Potassium per ct. : 0.27

Material : Corn, dent, Grade No. 4

Total dry matter per ct. : 81.1

Protein per ct. : 8.2

Fat per ct. : 3.7

Fiber per ct. : 1.9

N-free extract per ct. : 66.2

Total minerals per ct. : 1.1

Calcium per ct. : 0.02

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.31

Potassium per ct. : 0.26

Material : Corn, dent, Grade No. 5

Total dry matter per ct. : 78.5

Protein per ct. : 7.9

Fat per ct. : 3.6

Fiber per ct. : 1.9

N-free extract per ct. : 64.0

Total minerals per ct. : 1.1

Calcium per ct. : 0.02

Phosphorus per ct. : 0.25

Nitrogen per ct. : 1.26

Potassium per ct. : 0.25

Material : Corn, dent, soft or immature

Total dry matter per ct. : 70.0

Protein per ct. : 7.2

Fat per ct. : 2.3

Fiber per ct. : 2.5

N-free extract per ct. : 56.5

Total minerals per ct. : 1.5

Calcium per ct. : —

Phosphorus per ct. : 0.24

Nitrogen per ct. : 1.16

Potassium per ct. : 0.26

Material : Corn, flint

Total dry matter per ct. : 88.5

Protein per ct. : 9.8

Fat per ct. : 4.3

Fiber per ct. : 1.9

N-free extract per ct. : 71.0

Total minerals per ct. : 1.5

Calcium per ct. : —

Phosphorus per ct. : 0.33

Nitrogen per ct. : 1.57

Potassium per ct. : 0.32

Material : Corn, pop

Total dry matter per ct. : 90.0

Protein per ct. : 11.5

Fat per ct. : 5.0

Fiber per ct. : 1.9

N-free extract per ct. : 70.1

Total minerals per ct. : 1.5

Calcium per ct. : —

Phosphorus per ct. : 0.29

Nitrogen per ct. : 1.84

Potassium per ct. : —

Material : Corn ears, including kernels and cobs (corn-and-cob meal)

Total dry matter per ct. : 86.1

Protein per ct. : 7.3

Fat per ct. : 3.2

Fiber per ct. : 8.0

N-free extract per ct. : 66.3

Total minerals per ct. : 1.3

Calcium per ct. : —

Phosphorus per ct. : 0.22

Nitrogen per ct. : 1.17

Potassium per ct. : 0.29

Material : Corn ears, soft or immature

Total dry matter per ct. : 64.3

Protein per ct. : 5.8

Fat per ct. : 1.9

Fiber per ct. : 7.8

N-free extract per ct. : 47.7

Total minerals per ct. : 1.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.93

Potassium per ct. : —

Material : Corn, snapped, or ear-corn chops with husks

Total dry matter per ct. : 88.8

Protein per ct. : 8.0

Fat per ct. : 3.0

Fiber per ct. : 10.6

N-free extract per ct. : 64.8

Total minerals per ct. : 2.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.28

Potassium per ct. : —

Material : Corn, snapped, very soft or immature

Total dry matter per ct. : 60.0

Protein per ct. : 5.3

Fat per ct. : 1.8

Fiber per ct. : 8.2

N-free extract per ct. : 42.7

Total minerals per ct. : 2.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.85

Potassium per ct. : —

Material : Corn bran

Total dry matter per ct. : 90.6

Protein per ct. : 9.7

Fat per ct. : 7.3

Fiber per ct. : 9.2

N-free extract per ct. : 62.0

Total minerals per ct. : 2.4

Calcium per ct. : 0.03

Phosphorus per ct. : 0.27

Nitrogen per ct. : 1.56

Potassium per ct. : 0.56

Material : Corn feed meal

Total dry matter per ct. : 88.6

Protein per ct. : 9.8

Fat per ct. : 4.7

Fiber per ct. : 2.9

N-free extract per ct. : 69.2

Total minerals per ct. : 2.0

Calcium per ct. : 0.03

Phosphorus per ct. : 0.34

Nitrogen per ct. : 1.57

Potassium per ct. : 0.28

Material : Corn germ meal

Total dry matter per ct. : 93.0

Protein per ct. : 19.8

Fat per ct. : 7.8

Fiber per ct. : 8.9

N-free extract per ct. : 53.2

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : 0.58

Nitrogen per ct. : 3.17

Potassium per ct. : 0.21

Material : Corn gluten feed, all analyses

Total dry matter per ct. : 90.9

Protein per ct. : 25.5

Fat per ct. : 2.7

Fiber per ct. : 7.6

N-free extract per ct. : 48.8

Total minerals per ct. : 6.3

Calcium per ct. : 0.48

Phosphorus per ct. : 0.82

Nitrogen per ct. : 4.08

Potassium per ct. : 0.54

Material : Corn gluten feed, 25% protein guarantee

Total dry matter per ct. : 91.1

Protein per ct. : 26.6

Fat per ct. : 3.0

Fiber per ct. : 7.2

N-free extract per ct. : 48.2

Total minerals per ct. : 6.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.26

Potassium per ct. : —

Material : Corn gluten feed, 23% protein guarantee

Total dry matter per ct. : 91.4

Protein per ct. : 24.8

Fat per ct. : 2.6

Fiber per ct. : 7.8

N-free extract per ct. : 49.8

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.97

Potassium per ct. : —

Material : Corn gluten feed with molasses

Total dry matter per ct. : 88.8

Protein per ct. : 22.6

Fat per ct. : 2.1

Fiber per ct. : 6.8

N-free extract per ct. : 50.9

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.62

Potassium per ct. : —

Material : Corn gluten meal, all analyses

Total dry matter per ct. : 91.4

Protein per ct. : 43.1

Fat per ct. : 2.0

Fiber per ct. : 4.0

N-free extract per ct. : 39.8

Total minerals per ct. : 2.5

Calcium per ct. : 0.13

Phosphorus per ct. : 0.38

Nitrogen per ct. : 6.90

Potassium per ct. : 0.02

Material : Corn gluten meal, 41 % protein guarantee

Total dry matter per ct. : 91.4

Protein per ct. : 42.9

Fat per ct. : 2.0

Fiber per ct. : 3.9

N-free extract per ct. : 40.1

Total minerals per ct. : 2.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.86

Potassium per ct. : —

Material : Corn grits

Total dry matter per ct. : 88.4

Protein per ct. : 8.5

Fat per ct. : 0.5

Fiber per ct. : 0.6

N-free extract per ct. : 78.4

Total minerals per ct. : 0.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.36

Potassium per ct. : —

Material : Corn meal, degerminated, yellow

Total dry matter per ct. : 88.7

Protein per ct. : 8.7

Fat per ct. : 1.2

Fiber per ct. : 0.6

N-free extract per ct. : 77.1

Total minerals per ct. : 1.1

Calcium per ct. : 0.01

Phosphorus per ct. : 0.14

Nitrogen per ct. : 1.39

Potassium per ct. : —

Material : Corn meal, degerminated, white

Total dry matter per ct. : 88.4

Protein per ct. : 8.6

Fat per ct. : 1.2

Fiber per ct. : 0.7

N-free extract per ct. : 76.1

Total minerals per ct. : 1.8

Calcium per ct. : 0.01

Phosphorus per ct. : 0.14

Nitrogen per ct. : 1.38

Potassium per ct. : —

Material : Corn oil meal, old process

Total dry matter per ct. : 91.7

Protein per ct. : 22.3

Fat per ct. : 7.8

Fiber per ct. : 10.3

N-free extract per ct. : 49.0

Total minerals per ct. : 2.3

Calcium per ct. : 0.06

Phosphorus per ct. : 0.56

Nitrogen per ct. : 3.57

Potassium per ct. : —

Material : Corn oil meal, solvent process

Total dry matter per ct. : 91.7

Protein per ct. : 23.0

Fat per ct. : 1.5

Fiber per ct. : 10.4

N-free extract per ct. : 54.6

Total minerals per ct. : 2.2

Calcium per ct. : 0.03

Phosphorus per ct. : 0.50

Nitrogen per ct. : 3.68

Potassium per ct. : —

Material : Corn-starch

Total dry matter per ct. : 88.6

Protein per ct. : 11.6

Fat per ct. : 0.6

Fiber per ct. : 0.1

N-free extract per ct. : 0.2

Total minerals per ct. : 87.6

Calcium per ct. : 0.1

Phosphorus per ct. : —

Nitrogen per ct. : —

Potassium per ct. : 0.10

Material : Corn-and-oat feed, good grade

Total dry matter per ct. : 89.6

Protein per ct. : 11.9

Fat per ct. : 4.0

Fiber per ct. : 5.4

N-free extract per ct. : 65.9

Total minerals per ct. : 2.4

Calcium per ct. : 0.05

Phosphorus per ct. : 0.30

Nitrogen per ct. : 1.90

Potassium per ct. : 0.34

Material : Corn-and-oat feed, low grade

Total dry matter per ct. : 89.6

Protein per ct. : 9.1

Fat per ct. : 2.9

Fiber per ct. : 13.4

N-free extract per ct. : 59.0

Total minerals per ct. : 5.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.46

Potassium per ct. : —

Material : Cottonseed, whole

Total dry matter per ct. : 92.7

Protein per ct. : 23.1

Fat per ct. : 22.9

Fiber per ct. : 16.9

N-free extract per ct. : 26.3

Total minerals per ct. : 3.5

Calcium per ct. : 0.14

Phosphorus per ct. : 0.70

Nitrogen per ct. : 3.70

Potassium per ct. : 1.11

Material : Cottonseed, immature, dried

Total dry matter per ct. : 93.2

Protein per ct. : 20.5

Fat per ct. : 15.9

Fiber per ct. : 24.1

N-free extract per ct. : 29.0

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.28

Potassium per ct. : —

Material : Cottonseed, whole pressed, 28% protein guarantee

Total dry matter per ct. : 93.5

Protein per ct. : 28.2

Fat per ct. : 5.8

Fiber per ct. : 22.6

N-free extract per ct. : 32.2

Total minerals per ct. : 4.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.51

Potassium per ct. : —

Material : Cottonseed, whole pressed, below 28% protein

Total dry matter per ct. : 93.5

Protein per ct. : 26.9

Fat per ct. : 6.5

Fiber per ct. : 24.7

N-free extract per ct. : 30.8

Total minerals per ct. : 4.6

Calcium per ct. : 0.17

Phosphorus per ct. : 0.64

Nitrogen per ct. : 4.30

Potassium per ct. : 1.25

Material : Cottonseed feed, below 36% protein

Total dry matter per ct. : 92.4

Protein per ct. : 34.6

Fat per ct. : 6.3

Fiber per ct. : 14.1

N-free extract per ct. : 31.5

Total minerals per ct. : 5.9

Calcium per ct. : 0.26

Phosphorus per ct. : 0.83

Nitrogen per ct. : 5.54

Potassium per ct. : 1.22

Material : Cottonseed flour

Total dry matter per ct. : 94.4

Protein per ct. : 57.0

Fat per ct. : 7.2

Fiber per ct. : 2.1

N-free extract per ct. : 21.6

Total minerals per ct. : 6.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 9.12

Potassium per ct. : —

Material : Cottonseed kernels, without hulls

Total dry matter per ct. : 93.6

Protein per ct. : 38.4

Fat per ct. : 33.3

Fiber per ct. : 2.3

N-free extract per ct. : 15.1

Total minerals per ct. : 4.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.14

Potassium per ct. : —

Material : Cottonseed meal, 45% protein and over

Total dry matter per ct. : 93.5

Protein per ct. : 46.2

Fat per ct. : 7.7

Fiber per ct. : 8.6

N-free extract per ct. : 24.9

Total minerals per ct. : 6.1

Calcium per ct. : 0.22

Phosphorus per ct. : 1.13

Nitrogen per ct. : 7.39

Potassium per ct. : —

Material : Cottonseed meal, 43% protein grade, not including Texas analyses

Total dry matter per ct. : 92.7

Protein per ct. : 43.9

Fat per ct. : 7.1

Fiber per ct. : 9.0

N-free extract per ct. : 26.3

Total minerals per ct. : 6.4

Calcium per ct. : 0.23

Phosphorus per ct. : 1.12

Nitrogen per ct. : 7.02

Potassium per ct. : 1.45

Material : Cottonseed meal, 43% protein grade, Texas analyses

Total dry matter per ct. : 92.5

Protein per ct. : 42.7

Fat per ct. : 6.4

Fiber per ct. : 10.6

N-free extract per ct. : 27.0

Total minerals per ct. : 5.8

Calcium per ct. : 0.19

Phosphorus per ct. : 0.96

Nitrogen per ct. : 6.83

Potassium per ct. : 1.34

Material : Cottonseed meal, 41 % protein grade, not including Texas analyses

Total dry matter per ct. : 92.8

Protein per ct. : 41.5

Fat per ct. : 6.3

Fiber per ct. : 10.4

N-free extract per ct. : 28.1

Total minerals per ct. : 6.5

Calcium per ct. : 0.20

Phosphorus per ct. : 1.22

Nitrogen per ct. : 6.64

Potassium per ct. : 1.48

Material : Cottonseed meal, 41% protein grade, Texas analyses

Total dry matter per ct. : 92.1

Protein per ct. : 41.0

Fat per ct. : 6.0

Fiber per ct. : 11.6

N-free extract per ct. : 27.6

Total minerals per ct. : 5.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.56

Potassium per ct. : —

Material : Cottonseed meal, below 41 % protein grade

Total dry matter per ct. : 92.4

Protein per ct. : 38.2

Fat per ct. : 6.2

Fiber per ct. : 12.3

N-free extract per ct. : 29.4

Total minerals per ct. : 6.3

Calcium per ct. : 0.23

Phosphorus per ct. : 1.29

Nitrogen per ct. : 6.11

Potassium per ct. : 1.57

Material : Cottonseed meal, solvent process

Total dry matter per ct. : 90.8

Protein per ct. : 44.4

Fat per ct. : 2.6

Fiber per ct. : 12.7

N-free extract per ct. : 24.3

Total minerals per ct. : 6.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.10

Potassium per ct. : —

Material : Cowpea seed

Total dry matter per ct. : 89.0

Protein per ct. : 23.4

Fat per ct. : 1.4

Fiber per ct. : 4.0

N-free extract per ct. : 56.7

Total minerals per ct. : 3.5

Calcium per ct. : 0.11

Phosphorus per ct. : 0.46

Nitrogen per ct. : 3.74

Potassium per ct. : 1.30

Material : Crab meal

Total dry matter per ct. : 92.4

Protein per ct. : 31.5

Fat per ct. : 2.0

Fiber per ct. : 10.7

N-free extract per ct. : 5.0

Total minerals per ct. : 43.2

Calcium per ct. : 15.15

Phosphorus per ct. : 1.63

Nitrogen per ct. : 5.04

Potassium per ct. : 0.45

Material : Darso grain

Total dry matter per ct. : 90.0

Protein per ct. : 10.1

Fat per ct. : 3.1

Fiber per ct. : 1.9

N-free extract per ct. : 73.5

Total minerals per ct. : 1.4

Calcium per ct. : 0.02

Phosphorus per ct. : 0.32

Nitrogen per ct. : 1.62

Potassium per ct. : —

Material : Distillers’ dried corn grains, without solubles

Total dry matter per ct. : 92.9

Protein per ct. : 28.3

Fat per ct. : 8.8

Fiber per ct. : 11.4

N-free extract per ct. : 41.9

Total minerals per ct. : 2.5

Calcium per ct. : 0.11

Phosphorus per ct. : 0.47

Nitrogen per ct. : 4.53

Potassium per ct. : 0.24

Material : Distillers’ dried corn grains, with solubles

Total dry matter per ct. : 93.1

Protein per ct. : 28.8

Fat per ct. : 8.9

Fiber per ct. : 9.0

N-free extract per ct. : 41.7

Total minerals per ct. : 4.7

Calcium per ct. : 0.16

Phosphorus per ct. : 0.74

Nitrogen per ct. : 4.61

Potassium per ct. : —

Material : Distillers’ dried corn grains, solvent extracted

Total dry matter per ct. : 93.7

Protein per ct. : 33.4

Fat per ct. : 1.4

Fiber per ct. : 8.6

N-free extract per ct. : 46.4

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.34

Potassium per ct. : —

Material : Distillers’ dried rye grains

Total dry matter per ct. : 93.9

Protein per ct. : 18.5

Fat per ct. : 6.4

Fiber per ct. : 15.6

N-free extract per ct. : 51.0

Total minerals per ct. : 2.4

Calcium per ct. : 0.13

Phosphorus per ct. : 0.43

Nitrogen per ct. : 2.96

Potassium per ct. : 0.04

Material : Distillers’ rye grains, wet

Total dry matter per ct. : 22.4

Protein per ct. : 4.4

Fat per ct. : 1.5

Fiber per ct. : 2.5

N-free extract per ct. : 13.3

Total minerals per ct. : 0.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.70

Potassium per ct. : —

Material : Distillers’ dried wheat grains

Total dry matter per ct. : 93.7

Protein per ct. : 28.7

Fat per ct. : 6.1

Fiber per ct. : 13.0

N-free extract per ct. : 42.2

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.59

Potassium per ct. : —

Material : Distillers’ dried wheat grains, high protein

Total dry matter per ct. : 94.7

Protein per ct. : 46.2

Fat per ct. : 5.7

Fiber per ct. : 10.9

N-free extract per ct. : 30.0

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.39

Potassium per ct. : —

Material : Distillers’ solubles, dried, corn

Total dry matter per ct. : 93.0

Protein per ct. : 26.7

Fat per ct. : 7.9

Fiber per ct. : 2.6

N-free extract per ct. : 48.4

Total minerals per ct. : 7.4

Calcium per ct. : 0.30

Phosphorus per ct. : 1.41

Nitrogen per ct. : 4.27

Potassium per ct. : 1.75

Material : Distillers’ solubles, dried, wheat

Total dry matter per ct. : 94.0

Protein per ct. : 28.2

Fat per ct. : 1.5

Fiber per ct. : 2.8

N-free extract per ct. : 58.9

Total minerals per ct. : 2.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.51

Potassium per ct. : —

Material : Distillery stillage, corn, whole

Total dry matter per ct. : 7.9

Protein per ct. : 2.3

Fat per ct. : 0.6

Fiber per ct. : 0.7

N-free extract per ct. : 4.0

Total minerals per ct. : 0.3

Calcium per ct. : 0.006

Phosphorus per ct. : 0.05

Nitrogen per ct. : 0.37

Potassium per ct. : —

Material : Distillery stillage, rye, whole

Total dry matter per ct. : 5.9

Protein per ct. : 1.9

Fat per ct. : 0.3

Fiber per ct. : 0.5

N-free extract per ct. : 2.9

Total minerals per ct. : 0.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.30

Potassium per ct. : —

Material : Distillery stillage, strained

Total dry matter per ct. : 3.8

Protein per ct. : 1.1

Fat per ct. : 0.4

Fiber per ct. : 0.2

N-free extract per ct. : 1.8

Total minerals per ct. : 0.3

Calcium per ct. : 0.004

Phosphorus per ct. : 0.05

Nitrogen per ct. : 0.18

Potassium per ct. : —

Material : Durra grain

Total dry matter per ct. : 89.8

Protein per ct. : 10.3

Fat per ct. : 3.5

Fiber per ct. : 1.6

N-free extract per ct. : 72.4

Total minerals per ct. : 2.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.64

Potassium per ct. : —

Material : Emmer grain

Total dry matter per ct. : 91.1

Protein per ct. : 12.1

Fat per ct. : 1.9

Fiber per ct. : 9.8

N-free extract per ct. : 63.6

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : 0.33

Nitrogen per ct. : 1.94

Potassium per ct. : 0.47

Material : Feterita grain

Total dry matter per ct. : 89.4

Protein per ct. : 12.2

Fat per ct. : 3.2

Fiber per ct. : 2.2

N-free extract per ct. : 70.1

Total minerals per ct. : 1.7

Calcium per ct. : 0.02

Phosphorus per ct. : 0.33

Nitrogen per ct. : 1.96

Potassium per ct. : —

Material : Feterita head chops

Total dry matter per ct. : 89.6

Protein per ct. : 10.7

Fat per ct. : 2.6

Fiber per ct. : 7.4

N-free extract per ct. : 65.7

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.71

Potassium per ct. : —

Material : Fish-liver oil meal

Total dry matter per ct. : 92.8

Protein per ct. : 62.8

Fat per ct. : 17.3

Fiber per ct. : 1.2

N-free extract per ct. : 5.4

Total minerals per ct. : 6.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 10.04

Potassium per ct. : —

Material : Fish meal, all analyses

Total dry matter per ct. : 92.9

Protein per ct. : 63.9

Fat per ct. : 6.8

Fiber per ct. : 0.6

N-free extract per ct. : 4.0

Total minerals per ct. : 17.6

Calcium per ct. : 4.14

Phosphorus per ct. : 2.67

Nitrogen per ct. : 10.22

Potassium per ct. : 0.40

Material : Fish meal, over 63% protein

Total dry matter per ct. : 92.7

Protein per ct. : 66.8

Fat per ct. : 5.3

Fiber per ct. : 0.5

N-free extract per ct. : 4.5

Total minerals per ct. : 15.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 10.69

Potassium per ct. : —

Material : Fish meal, 58-63% protein

Total dry matter per ct. : 93.1

Protein per ct. : 60.9

Fat per ct. : 8.1

Fiber per ct. : 0.8

N-free extract per ct. : 3.5

Total minerals per ct. : 19.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 9.74

Potassium per ct. : —

Material : Fish meal, below 58% protein

Total dry matter per ct. : 93.2

Protein per ct. : 56.2

Fat per ct. : 11.0

Fiber per ct. : 0.7

N-free extract per ct. : 2.9

Total minerals per ct. : 22.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 8.99

Potassium per ct. : —

Material : Fish meal, herring

Total dry matter per ct. : 93.5

Protein per ct. : 72.5

Fat per ct. : 7.3

Fiber per ct. : 0.7

N-free extract per ct. : 1.5

Total minerals per ct. : 11.5

Calcium per ct. : 2.97

Phosphorus per ct. : 2.08

Nitrogen per ct. : 11.60

Potassium per ct. : —

Material : Fish meal, menhaden

Total dry matter per ct. : 93.6

Protein per ct. : 62.2

Fat per ct. : 8.5

Fiber per ct. : 0.7

N-free extract per ct. : 4.2

Total minerals per ct. : 18.0

Calcium per ct. : 5.30

Phosphorus per ct. : 3.38

Nitrogen per ct. : 9.96

Potassium per ct. : —

Material : Fish meal, redfish

Total dry matter per ct. : 94.2

Protein per ct. : 56.7

Fat per ct. : 11.4

Fiber per ct. : 0.9

N-free extract per ct. : 0.9

Total minerals per ct. : 24.3

Calcium per ct. : 4.01

Phosphorus per ct. : 2.44

Nitrogen per ct. : 9.07

Potassium per ct. : —

Material : Fish meal, salmon

Total dry matter per ct. : 92.8

Protein per ct. : 59.4

Fat per ct. : 9.8

Fiber per ct. : 0.3

N-free extract per ct. : 4.3

Total minerals per ct. : 19.0

Calcium per ct. : 5.49

Phosphorus per ct. : 3.65

Nitrogen per ct. : 9.50

Potassium per ct. : —

Material : Fish meal, sardine

Total dry matter per ct. : 93.1

Protein per ct. : 67.2

Fat per ct. : 5.0

Fiber per ct. : 0.6

N-free extract per ct. : 5.4

Total minerals per ct. : 14.9

Calcium per ct. : 4.21

Phosphorus per ct. : 2.54

Nitrogen per ct. : 10.76

Potassium per ct. : 0.33

Material : Fish meal, tuna

Total dry matter per ct. : 90.1

Protein per ct. : 58.2

Fat per ct. : 7.9

Fiber per ct. : 0.7

N-free extract per ct. : 3.4

Total minerals per ct. : 19.9

Calcium per ct. : 4.80

Phosphorus per ct. : 3.10

Nitrogen per ct. : 9.31

Potassium per ct. : —

Material : Fish meal, whitefish

Total dry matter per ct. : 90.4

Protein per ct. : 63.0

Fat per ct. : 6.7

Fiber per ct. : 0.1

N-free extract per ct. : 0.1

Total minerals per ct. : 20.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 10.08

Potassium per ct. : —

Material : Fish solubles, condensed

Total dry matter per ct. : 49.5

Protein per ct. : 29.3

Fat per ct. : 8.4

Fiber per ct. : —

N-free extract per ct. : 2.2

Total minerals per ct. : 9.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.69

Potassium per ct. : —

Material : Flaxseed

Total dry matter per ct. : 93.8

Protein per ct. : 24.0

Fat per ct. : 35.9

Fiber per ct. : 6.3

N-free extract per ct. : 24.0

Total minerals per ct. : 3.6

Calcium per ct. : 0.26

Phosphorus per ct. : 0.55

Nitrogen per ct. : 3.84

Potassium per ct. : 0.59

Material : Flaxseed screenings

Total dry matter per ct. : 91.1

Protein per ct. : 16.4

Fat per ct. : 9.4

Fiber per ct. : 12.7

N-free extract per ct. : 45.8

Total minerals per ct. : 6.8

Calcium per ct. : 0.37

Phosphorus per ct. : 0.43

Nitrogen per ct. : 2.62

Potassium per ct. : —

Material : Flaxseed screenings oil feed

Total dry matter per ct. : 91.9

Protein per ct. : 25.0

Fat per ct. : 7.1

Fiber per ct. : 11.7

N-free extract per ct. : 40.3

Total minerals per ct. : 7.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.00

Potassium per ct. : —

Material : Garbage

Total dry matter per ct. : 39.3

Protein per ct. : 6.0

Fat per ct. : 7.2

Fiber per ct. : 1.1

N-free extract per ct. : 22.2

Total minerals per ct. : 2.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.96

Potassium per ct. : —

Material : Garbage, processed, high in fat

Total dry matter per ct. : 95.9

Protein per ct. : 17.5

Fat per ct. : 23.7

Fiber per ct. : 20.0

N-free extract per ct. : 21.8

Total minerals per ct. : 12.9

Calcium per ct. : —

Phosphorus per ct. : 0.33

Nitrogen per ct. : 2.80

Potassium per ct. : 0.62

Material : Garbage, processed, low in fat

Total dry matter per ct. : 92.3

Protein per ct. : 23.1

Fat per ct. : 3.5

Fiber per ct. : 13.5

N-free extract per ct. : 38.1

Total minerals per ct. : 14.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.70

Potassium per ct. : —

Material : Grapefruit pulp, dried

Total dry matter per ct. : 91.7

Protein per ct. : 4.9

Fat per ct. : 1.1

Fiber per ct. : 11.9

N-free extract per ct. : 69.6

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.78

Potassium per ct. : —

Material : Grape pomace, dried

Total dry matter per ct. : 91.0

Protein per ct. : 12.2

Fat per ct. : 6.9

Fiber per ct. : 30.2

N-free extract per ct. : 36.7

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.96

Potassium per ct. : —

Material : Hegari grain

Total dry matter per ct. : 89.7

Protein per ct. : 9.6

Fat per ct. : 2.6

Fiber per ct. : 2.0

N-free extract per ct. : 73.9

Total minerals per ct. : 1.6

Calcium per ct. : 0.18

Phosphorus per ct. : 0.30

Nitrogen per ct. : 1.54

Potassium per ct. : —

Material : Hegari head chops

Total dry matter per ct. : 89.6

Protein per ct. : 10.0

Fat per ct. : 2.1

Fiber per ct. : 11.9

N-free extract per ct. : 60.6

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.60

Potassium per ct. : —

Material : Hempseed oil meal

Total dry matter per ct. : 92.0

Protein per ct. : 31.0

Fat per ct. : 6.2

Fiber per ct. : 23.8

N-free extract per ct. : 22.0

Total minerals per ct. : 9.0

Calcium per ct. : 0.25

Phosphorus per ct. : 0.43

Nitrogen per ct. : 4.96

Potassium per ct. : —

Material : Hominy feed, 5% fat or more

Total dry matter per ct. : 90.4

Protein per ct. : 11.2

Fat per ct. : 6.9

Fiber per ct. : 5.2

N-free extract per ct. : 64.2

Total minerals per ct. : 2.9

Calcium per ct. : 0.22

Phosphorus per ct. : 0.71

Nitrogen per ct. : 1.79

Potassium per ct. : 0.61

Material : Hominy feed, low in fat

Total dry matter per ct. : 89.7

Protein per ct. : 10.6

Fat per ct. : 4.3

Fiber per ct. : 5.0

N-free extract per ct. : 67.4

Total minerals per ct. : 2.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.70

Potassium per ct. : —

Material : Horse beans

Total dry matter per ct. : 87.5

Protein per ct. : 25.7

Fat per ct. : 1.4

Fiber per ct. : 8.2

N-free extract per ct. : 48.8

Total minerals per ct. : 3.4

Calcium per ct. : 0.13

Phosphorus per ct. : 0.54

Nitrogen per ct. : 4.11

Potassium per ct. : 1.16

Material : Ivory nut meal, vegetable

Total dry matter per ct. : 89.4

Protein per ct. : 4.7

Fat per ct. : 0.9

Fiber per ct. : 7.2

N-free extract per ct. : 75.5

Total minerals per ct. : 1.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.76

Potassium per ct. : —

Material : Jack beans

Total dry matter per ct. : 89.3

Protein per ct. : 24.7

Fat per ct. : 3.2

Fiber per ct. : 8.2

N-free extract per ct. : 50.4

Total minerals per ct. : 2.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.96

Potassium per ct. : —

Material : Kafir grain

Total dry matter per ct. : 89.8

Protein per ct. : 10.9

Fat per ct. : 2.9

Fiber per ct. : 1.7

N-free extract per ct. : 72.7

Total minerals per ct. : 1.6

Calcium per ct. : 0.02

Phosphorus per ct. : 0.31

Nitrogen per ct. : 1.74

Potassium per ct. : 0.34

Material : Kafir head chops

Total dry matter per ct. : 89.2

Protein per ct. : 10.0

Fat per ct. : 2.6

Fiber per ct. : 6.9

N-free extract per ct. : 66.4

Total minerals per ct. : 3.3

Calcium per ct. : 0.08

Phosphorus per ct. : 0.27

Nitrogen per ct. : 1.60

Potassium per ct. : —

Material : Kalo sorghum grain

Total dry matter per ct. : 89.2

Protein per ct. : 11.8

Fat per ct. : 3.2

Fiber per ct. : 1.6

N-free extract per ct. : 70.9

Total minerals per ct. : 1.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.89

Potassium per ct. : —

Material : Kaoliang grain

Total dry matter per ct. : 89.9

Protein per ct. : 10.5

Fat per ct. : 4.1

Fiber per ct. : 1.6

N-free extract per ct. : 71.8

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.68

Potassium per ct. : —

Material : Kelp, dried

Total dry matter per ct. : 91.3

Protein per ct. : 6.5

Fat per ct. : 0.5

Fiber per ct. : 6.5

N-free extract per ct. : 42.6

Total minerals per ct. : 35.2

Calcium per ct. : 2.48

Phosphorus per ct. : 0.28

Nitrogen per ct. : 1.04

Potassium per ct. : —

Material : Lamb’s-quarters seed

Total dry matter per ct. : 90.0

Protein per ct. : 20.6

Fat per ct. : 4.5

Fiber per ct. : 15.1

N-free extract per ct. : 40.2

Total minerals per ct. : 9.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.30

Potassium per ct. : —

Material : Lespedeza seed, annual

Total dry matter per ct. : 91.7

Protein per ct. : 36.6

Fat per ct. : 7.6

Fiber per ct. : 9.6

N-free extract per ct. : 32.8

Total minerals per ct. : 5.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.86

Potassium per ct. : —

Material : Lespedeza seed, sericea

Total dry matter per ct. : 92.3

Protein per ct. : 33.5

Fat per ct. : 4.2

Fiber per ct. : 13.5

N-free extract per ct. : 37.3

Total minerals per ct. : 3.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.36

Potassium per ct. : —

Material : Lemon pulp, dried

Total dry matter per ct. : 92.8

Protein per ct. : 6.4

Fat per ct. : 1.2

Fiber per ct. : 15.0

N-free extract per ct. : 65.2

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.02

Potassium per ct. : —

Material : Linseed meal, old process, all analyses

Total dry matter per ct. : 91.0

Protein per ct. : 35.4

Fat per ct. : 5.8

Fiber per ct. : 8.2

N-free extract per ct. : 36.0

Total minerals per ct. : 5.6

Calcium per ct. : 0.39

Phosphorus per ct. : 0.87

Nitrogen per ct. : 5.66

Potassium per ct. : 1.24

Material : Linseed meal, o.p., 37% protein or more

Total dry matter per ct. : 90.9

Protein per ct. : 38.0

Fat per ct. : 5.9

Fiber per ct. : 7.7

N-free extract per ct. : 33.7

Total minerals per ct. : 5.6

Calcium per ct. : 0.39

Phosphorus per ct. : 0.86

Nitrogen per ct. : 6.08

Potassium per ct. : 1.10

Material : Linseed meal, o.p., 33-37% protein

Total dry matter per ct. : 91.0

Protein per ct. : 35.0

Fat per ct. : 5.7

Fiber per ct. : 8.3

N-free extract per ct. : 36.4

Total minerals per ct. : 5.6

Calcium per ct. : 0.41

Phosphorus per ct. : 0.86

Nitrogen per ct. : 5.60

Potassium per ct. : 1.14

Material : Linseed meal, o.p., 31-33% protein

Total dry matter per ct. : 91.0

Protein per ct. : 32.4

Fat per ct. : 5.9

Fiber per ct. : 8.3

N-free extract per ct. : 38.7

Total minerals per ct. : 5.7

Calcium per ct. : 0.36

Phosphorus per ct. : 0.90

Nitrogen per ct. : 5.18

Potassium per ct. : 1.40

Material : Linseed meal, solvent process, older analyses

Total dry matter per ct. : 90.4

Protein per ct. : 36.9

Fat per ct. : 2.9

Fiber per ct. : 8.7

N-free extract per ct. : 36.3

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.90

Potassium per ct. : —

Material : Linseed meal and screenings oil feed (linseed feed)

Total dry matter per ct. : 90.5

Protein per ct. : 31.2

Fat per ct. : 5.4

Fiber per ct. : 10.1

N-free extract per ct. : 37.0

Total minerals per ct. : 6.8

Calcium per ct. : 0.43

Phosphorus per ct. : 0.65

Nitrogen per ct. : 4.99

Potassium per ct. : —

Material : Liver meal, animal

Total dry matter per ct. : 92.3

Protein per ct. : 66.2

Fat per ct. : 16.4

Fiber per ct. : 1.4

N-free extract per ct. : 1.9

Total minerals per ct. : 6.4

Calcium per ct. : 0.62

Phosphorus per ct. : 1.27

Nitrogen per ct. : 10.59

Potassium per ct. : —

Material : Locust beans and pods, honey

Total dry matter per ct. : 88.4

Protein per ct. : 9.3

Fat per ct. : 2.4

Fiber per ct. : 16.1

N-free extract per ct. : 57.1

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.49

Potassium per ct. : —

Material : Lupine seed, sweet, yellow

Total dry matter per ct. : 88.9

Protein per ct. : 39.8

Fat per ct. : 4.9

Fiber per ct. : 14.0

N-free extract per ct. : 25.7

Total minerals per ct. : 4.5

Calcium per ct. : 0.23

Phosphorus per ct. : 0.39

Nitrogen per ct. : 6.37

Potassium per ct. : 0.81

Material : Malt, barley

Total dry matter per ct. : 90.6

Protein per ct. : 14.3

Fat per ct. : 1.6

Fiber per ct. : 1.8

N-free extract per ct. : 70.6

Total minerals per ct. : 2.3

Calcium per ct. : 0.08

Phosphorus per ct. : 0.47

Nitrogen per ct. : 2.29

Potassium per ct. : —

Material : Malt sprouts

Total dry matter per ct. : 92.6

Protein per ct. : 26.8

Fat per ct. : 1.3

Fiber per ct. : 14.2

N-free extract per ct. : 44.3

Total minerals per ct. : 6.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.29

Potassium per ct. : —

Material : Meat scraps, or dry-rendered tankage, 60% protein grade

Total dry matter per ct. : 93.8

Protein per ct. : 60.9

Fat per ct. : 8.8

Fiber per ct. : 2.4

N-free extract per ct. : 1.1

Total minerals per ct. : 20.6

Calcium per ct. : 6.09

Phosphorus per ct. : 3.49

Nitrogen per ct. : 9.74

Potassium per ct. : —

Material : Meat scraps, or dry-rendered tankage, 55% protein grade

Total dry matter per ct. : 93.9

Protein per ct. : 55.8

Fat per ct. : 9.3

Fiber per ct. : 2.1

N-free extract per ct. : 1.3

Total minerals per ct. : 25.4

Calcium per ct. : 8.33

Phosphorus per ct. : 4.04

Nitrogen per ct. : 8.93

Potassium per ct. : —

Material : Meat scraps, or dry-rendered tankage, 55% protein grade, low fat

Total dry matter per ct. : 93.0

Protein per ct. : 56.0

Fat per ct. : 3.5

Fiber per ct. : 2.6

N-free extract per ct. : 1.5

Total minerals per ct. : 29.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 8.96

Potassium per ct. : —

Material : Meat scraps, or dry-rendered tankage, 52% protein grade

Total dry matter per ct. : 93.1

Protein per ct. : 52.9

Fat per ct. : 7.3

Fiber per ct. : 2.2

N-free extract per ct. : 4.3

Total minerals per ct. : 26.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 8.46

Potassium per ct. : —

Material : Meat and bone scraps, or dry-rendered tankage with bone, 50% protein grade

Total dry matter per ct. : 93.9

Protein per ct. : 51.0

Fat per ct. : 10.1

Fiber per ct. : 2.1

N-free extract per ct. : 1.6

Total minerals per ct. : 29.1

Calcium per ct. : 9.71

Phosphorus per ct. : 4.81

Nitrogen per ct. : 8.16

Potassium per ct. : —

Material : Meat and bone scraps, or dry-rendered tankage with bone, 45% protein grade

Total dry matter per ct. : 94.5

Protein per ct. : 46.3

Fat per ct. : 12.0

Fiber per ct. : 2.0

N-free extract per ct. : 2.3

Total minerals per ct. : 31.9

Calcium per ct. : 11.21

Phosphorus per ct. : 4.88

Nitrogen per ct. : 7.41

Potassium per ct. : —

Material : Mesquite beans and pods

Total dry matter per ct. : 94.0

Protein per ct. : 13.0

Fat per ct. : 2.8

Fiber per ct. : 26.3

N-free extract per ct. : 47.4

Total minerals per ct. : 4.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.08

Potassium per ct. : —

Material : Milk, cow’s

Total dry matter per ct. : 12.8

Protein per ct. : 3.5

Fat per ct. : 3.7

Fiber per ct. : 0

N-free extract per ct. : 4.9

Total minerals per ct. : 0.7

Calcium per ct. : 0.12

Phosphorus per ct. : 0.09

Nitrogen per ct. : 0.56

Potassium per ct. : 0.14

Material : Milk, ewe’s

Total dry matter per ct. : 19.2

Protein per ct. : 6.5

Fat per ct. : 6.9

Fiber per ct. : 0

N-free extract per ct. : 4.9

Total minerals per ct. : 0.9

Calcium per ct. : 0.21

Phosphorus per ct. : 0.12

Nitrogen per ct. : 1.04

Potassium per ct. : 0.19

Material : Milk, goat’s

Total dry matter per ct. : 12.8

Protein per ct. : 3.7

Fat per ct. : 4.1

Fiber per ct. : 0

N-free extract per ct. : 4.2

Total minerals per ct. : 0.8

Calcium per ct. : 0.13

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.59

Potassium per ct. : 0.15

Material : Milk, mare’s

Total dry matter per ct. : 9.4

Protein per ct. : 2.0

Fat per ct. : 1.1

Fiber per ct. : 0

N-free extract per ct. : 5.9

Total minerals per ct. : 0.4

Calcium per ct. : 0.08

Phosphorus per ct. : 0.05

Nitrogen per ct. : 0.32

Potassium per ct. : 0.08

Material : Milk, sow’s

Total dry matter per ct. : 19.0

Protein per ct. : 5.9

Fat per ct. : 6.7

Fiber per ct. : 0

N-free extract per ct. : 5.4

Total minerals per ct. : 1.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.94

Potassium per ct. : —

Material : Milk albumin, or lactalbumin, commercial

Total dry matter per ct. : 92.0

Protein per ct. : 49.5

Fat per ct. : 0.9

Fiber per ct. : 1.0

N-free extract per ct. : 12.8

Total minerals per ct. : 27.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.92

Potassium per ct. : —

Material : Milk, whole, dried

Total dry matter per ct. : 96.8

Protein per ct. : 24.8

Fat per ct. : 26.2

Fiber per ct. : 0.2

N-free extract per ct. : 40.2

Total minerals per ct. : 5.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.97

Potassium per ct. : —

Material : Millet seed, foxtail varieties

Total dry matter per ct. : 89.1

Protein per ct. : 12.1

Fat per ct. : 4.1

Fiber per ct. : 8.6

N-free extract per ct. : 60.7

Total minerals per ct. : 3.6

Calcium per ct. : —

Phosphorus per ct. : 0.20

Nitrogen per ct. : 1.94

Potassium per ct. : 0.31

Material : Millet seed, hog, or proso

Total dry matter per ct. : 90.4

Protein per ct. : 11.9

Fat per ct. : 3.4

Fiber per ct. : 8.1

N-free extract per ct. : 63.7

Total minerals per ct. : 3.3

Calcium per ct. : 0.05

Phosphorus per ct. : 0.30

Nitrogen per ct. : 1.90

Potassium per ct. : 0.43

Material : Millet seed, Japanese

Total dry matter per ct. : 89.8

Protein per ct. : 10.6

Fat per ct. : 4.9

Fiber per ct. : 14.6

N-free extract per ct. : 54.7

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : 0.44

Nitrogen per ct. : 1.70

Potassium per ct. : 0.33

Material : Milo grain

Total dry matter per ct. : 89.4

Protein per ct. : 11.3

Fat per ct. : 2.9

Fiber per ct. : 2.2

N-free extract per ct. : 71.3

Total minerals per ct. : 1.7

Calcium per ct. : 0.03

Phosphorus per ct. : 0.30

Nitrogen per ct. : 1.81

Potassium per ct. : 0.36

Material : Milo head chops

Total dry matter per ct. : 90.1

Protein per ct. : 10.2

Fat per ct. : 2.5

Fiber per ct. : 6.9

N-free extract per ct. : 66.2

Total minerals per ct. : 4.3

Calcium per ct. : 0.14

Phosphorus per ct. : 0.26

Nitrogen per ct. : 1.63

Potassium per ct. : —

Material : Molasses, beet

Total dry matter per ct. : 80.5

Protein per ct. : 8.4

Fat per ct. : 0

Fiber per ct. : 0

N-free extract per ct. : 62.0

Total minerals per ct. : 10.1

Calcium per ct. : 0.08

Phosphorus per ct. : 0.02

Nitrogen per ct. : 1.34

Potassium per ct. : 4.77

Material : Molasses, beet, Steffen’s process

Total dry matter per ct. : 78.7

Protein per ct. : 7.8

Fat per ct. : 0

Fiber per ct. : 0

N-free extract per ct. : 62.1

Total minerals per ct. : 8.8

Calcium per ct. : 0.11

Phosphorus per ct. : 0.02

Nitrogen per ct. : 1.25

Potassium per ct. : 4.66

Material : Molasses, cane, or blackstrap

Total dry matter per ct. : 74.0

Protein per ct. : 2.9

Fat per ct. : 0

Fiber per ct. : 0

N-free extract per ct. : 62.1

Total minerals per ct. : 9.0

Calcium per ct. : 0.74

Phosphorus per ct. : 0.08

Nitrogen per ct. : 0.46

Potassium per ct. : 3.67

Material : Molasses, cane, high in sugar

Total dry matter per ct. : 79.7

Protein per ct. : 1.3

Fat per ct. : 0

Fiber per ct. : 0

N-free extract per ct. : 74.9

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.21

Potassium per ct. : —

Material : Molasses, citrus

Total dry matter per ct. : 69.9

Protein per ct. : 4.0

Fat per ct. : 0.2

Fiber per ct. : 0

N-free extract per ct. : 61.3

Total minerals per ct. : 4.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.64

Potassium per ct. : —

Material : Molasses, corn sugar, or hydrol

Total dry matter per ct. : 80.5

Protein per ct. : 0.2

Fat per ct. : 0

Fiber per ct. : 0

N-free extract per ct. : 77.8

Total minerals per ct. : 2.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.03

Potassium per ct. : —

Material : Mustard seed, wild yellow

Total dry matter per ct. : 95.9

Protein per ct. : 23.0

Fat per ct. : 38.8

Fiber per ct. : 5.0

N-free extract per ct. : 23.6

Total minerals per ct. : 5.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.68

Potassium per ct. : —

Material : Oat clippings, or clipped-oat by-product

Total dry matter per ct. : 92.2

Protein per ct. : 8.8

Fat per ct. : 2.3

Fiber per ct. : 25.3

N-free extract per ct. : 44.9

Total minerals per ct. : 10.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.41

Potassium per ct. : —

Material : Oat kernels, without hulls (oat groats)

Total dry matter per ct. : 90.4

Protein per ct. : 16.3

Fat per ct. : 6.1

Fiber per ct. : 2.1

N-free extract per ct. : 63.7

Total minerals per ct. : 2.2

Calcium per ct. : 0.08

Phosphorus per ct. : 0.46

Nitrogen per ct. : 2.61

Potassium per ct. : 0.39

Material : Oat meal, feeding, or rolled oats without hulls

Total dry matter per ct. : 90.8

Protein per ct. : 16.0

Fat per ct. : 5.5

Fiber per ct. : 2.7

N-free extract per ct. : 64.2

Total minerals per ct. : 2.4

Calcium per ct. : 0.07

Phosphorus per ct. : 0.46

Nitrogen per ct. : 2.56

Potassium per ct. : 0.37

Material : Oat middlings

Total dry matter per ct. : 91.4

Protein per ct. : 15.9

Fat per ct. : 5.2

Fiber per ct. : 3.3

N-free extract per ct. : 64.6

Total minerals per ct. : 2.4

Calcium per ct. : 0.08

Phosphorus per ct. : 0.45

Nitrogen per ct. : 2.54

Potassium per ct. : 0.57

Material : Oat mill feed

Total dry matter per ct. : 92.4

Protein per ct. : 5.6

Fat per ct. : 1.8

Fiber per ct. : 27.9

N-free extract per ct. : 50.8

Total minerals per ct. : 6.3

Calcium per ct. : 0.13

Phosphorus per ct. : 0.16

Nitrogen per ct. : 0.90

Potassium per ct. : 0.60

Material : Oat mill feed, poor grade

Total dry matter per ct. : 92.4

Protein per ct. : 4.3

Fat per ct. : 1.8

Fiber per ct. : 30.5

N-free extract per ct. : 50.2

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.69

Potassium per ct. : —

Material : Oat mill feed, with molasses

Total dry matter per ct. : 92.4

Protein per ct. : 5.5

Fat per ct. : 1.4

Fiber per ct. : 24.1

N-free extract per ct. : 55.0

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.88

Potassium per ct. : —

Material : Oats, not including Pacific Coast states

Total dry matter per ct. : 90.2

Protein per ct. : 12.0

Fat per ct. : 4.6

Fiber per ct. : 11.0

N-free extract per ct. : 58.6

Total minerals per ct. : 4.0

Calcium per ct. : 0.09

Phosphorus per ct. : 0.34

Nitrogen per ct. : 1.92

Potassium per ct. : 0.43

Material : Oats, Pacific Coast states

Total dry matter per ct. : 91.2

Protein per ct. : 9.0

Fat per ct. : 5.4

Fiber per ct. : 11.0

N-free extract per ct. : 62.1

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.44

Potassium per ct. : —

Material : Oats, hull-less

Total dry matter per ct. : 90.0

Protein per ct. : 15.4

Fat per ct. : 4.2

Fiber per ct. : 2.6

N-free extract per ct. : 65.7

Total minerals per ct. : 2.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.46

Potassium per ct. : —

Material : Oats, light weight

Total dry matter per ct. : 91.3

Protein per ct. : 12.3

Fat per ct. : 4.7

Fiber per ct. : 15.4

N-free extract per ct. : 54.4

Total minerals per ct. : 4.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.97

Potassium per ct. : —

Material : Oats, wild

Total dry matter per ct. : 89.0

Protein per ct. : 12.7

Fat per ct. : 5.5

Fiber per ct. : 15.2

N-free extract per ct. : 50.9

Total minerals per ct. : 4.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.03

Potassium per ct. : —

Material : Olive pulp, dried, pits removed

Total dry matter per ct. : 95.1

Protein per ct. : 14.0

Fat per ct. : 27.4

Fiber per ct. : 19.3

N-free extract per ct. : 31.0

Total minerals per ct. : 3.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.24

Potassium per ct. : —

Material : Olive pulp, dried, with pits

Total dry matter per ct. : 92.0

Protein per ct. : 5.9

Fat per ct. : 15.6

Fiber per ct. : 36.5

N-free extract per ct. : 31.5

Total minerals per ct. : 2.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.94

Potassium per ct. : —

Material : Orange pulp, dried

Total dry matter per ct. : 87.9

Protein per ct. : 7.7

Fat per ct. : 1.5

Fiber per ct. : 8.0

N-free extract per ct. : 67.3

Total minerals per ct. : 3.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.23

Potassium per ct. : —

Material : Palm-kernel oil meal

Total dry matter per ct. : 91.4

Protein per ct. : 19.2

Fat per ct. : 6.7

Fiber per ct. : 11.9

N-free extract per ct. : 49.7

Total minerals per ct. : 3.9

Calcium per ct. : —

Phosphorus per ct. : 0.69

Nitrogen per ct. : 3.07

Potassium per ct. : 0.42

Material : Palm seed, Royal

Total dry matter per ct. : 86.5

Protein per ct. : 6.1

Fat per ct. : 8.3

Fiber per ct. : 22.8

N-free extract per ct. : 43.8

Total minerals per ct. : 5.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.98

Potassium per ct. : —

Material : Palmo middlings

Total dry matter per ct. : 94.1

Protein per ct. : 16.1

Fat per ct. : 9.7

Fiber per ct. : 6.7

N-free extract per ct. : 56.3

Total minerals per ct. : 5.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.58

Potassium per ct. : —

Material : Pea feed, or pea meal

Total dry matter per ct. : 90.0

Protein per ct. : 17.7

Fat per ct. : 1.4

Fiber per ct. : 23.7

N-free extract per ct. : 43.7

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.83

Potassium per ct. : —

Material : Pea hulls of seeds, or bran

Total dry matter per ct. : 91.5

Protein per ct. : 4.8

Fat per ct. : 0.4

Fiber per ct. : 48.5

N-free extract per ct. : 34.3

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.77

Potassium per ct. : —

Material : Pea seed, field

Total dry matter per ct. : 90.7

Protein per ct. : 23.4

Fat per ct. : 1.2

Fiber per ct. : 6.1

N-free extract per ct. : 57.0

Total minerals per ct. : 3.0

Calcium per ct. : 0.17

Phosphorus per ct. : 0.51

Nitrogen per ct. : 3.74

Potassium per ct. : 1.03

Material : Pea seed, field, cull

Total dry matter per ct. : 89.7

Protein per ct. : 24.8

Fat per ct. : 2.5

Fiber per ct. : 7.1

N-free extract per ct. : 52.0

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.97

Potassium per ct. : —

Material : Pea seed, garden

Total dry matter per ct. : 89.2

Protein per ct. : 25.3

Fat per ct. : 1.7

Fiber per ct. : 5.7

N-free extract per ct. : 53.6

Total minerals per ct. : 2.9

Calcium per ct. : 0.08

Phosphorus per ct. : 0.40

Nitrogen per ct. : 4.04

Potassium per ct. : 0.90

Material : Peanut kernels, without hulls

Total dry matter per ct. : 94.6

Protein per ct. : 30.4

Fat per ct. : 47.7

Fiber per ct. : 2.5

N-free extract per ct. : 11.7

Total minerals per ct. : 2.3

Calcium per ct. : 0.06

Phosphorus per ct. : 0.44

Nitrogen per ct. : 4.86

Potassium per ct. : —

Material : Peanut oil feed

Total dry matter per ct. : 94.5

Protein per ct. : 37.8

Fat per ct. : 9.6

Fiber per ct. : 14.3

N-free extract per ct. : 26.2

Total minerals per ct. : 6.6

Calcium per ct. : —

Phosphorus per ct. : 6.04

Nitrogen per ct. : —

Potassium per ct. : —

Material : Peanut oil feed, unhulled, or whole pressed peanuts

Total dry matter per ct. : 93.1

Protein per ct. : 35.0

Fat per ct. : 9.2

Fiber per ct. : 22.5

N-free extract per ct. : 21.4

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.60

Potassium per ct. : —

Material : Peanut oil meal, old process, all analyses

Total dry matter per ct. : 93.0

Protein per ct. : 43.5

Fat per ct. : 7.6

Fiber per ct. : 13.3

N-free extract per ct. : 23.4

Total minerals per ct. : 5.2

Calcium per ct. : 0.16

Phosphorus per ct. : 0.54

Nitrogen per ct. : 6.96

Potassium per ct. : 1.15

Material : Peanut oil meal, o.p., 45% protein and over

Total dry matter per ct. : 93.4

Protein per ct. : 45.2

Fat per ct. : 7.4

Fiber per ct. : 12.1

N-free extract per ct. : 23.7

Total minerals per ct. : 5.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.23

Potassium per ct. : —

Material : Peanut oil meal, o.p., 43% protein grade

Total dry matter per ct. : 92.8

Protein per ct. : 43.1

Fat per ct. : 7.6

Fiber per ct. : 13.9

N-free extract per ct. : 23.0

Total minerals per ct. : 5.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.90

Potassium per ct. : —

Material : Peanut oil meal, o.p., 41% protein grade

Total dry matter per ct. : 93.8

Protein per ct. : 41.8

Fat per ct. : 7.8

Fiber per ct. : 12.7

N-free extract per ct. : 25.9

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.69

Potassium per ct. : —

Material : Peanut oil meal, solvent process

Total dry matter per ct. : 91.6

Protein per ct. : 51.5

Fat per ct. : 1.4

Fiber per ct. : 5.7

N-free extract per ct. : 27.2

Total minerals per ct. : 5.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 8.24

Potassium per ct. : —

Material : Peanut skins

Total dry matter per ct. : 93.8

Protein per ct. : 16.3

Fat per ct. : 23.9

Fiber per ct. : 11.8

N-free extract per ct. : 39.1

Total minerals per ct. : 2.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.61

Potassium per ct. : —

Material : Peanut screenings

Total dry matter per ct. : 93.6

Protein per ct. : 23.8

Fat per ct. : 11.5

Fiber per ct. : 18.9

N-free extract per ct. : 33.0

Total minerals per ct. : 6.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.81

Potassium per ct. : —

Material : Peanuts, with hulls

Total dry matter per ct. : 94.1

Protein per ct. : 24.9

Fat per ct. : 36.2

Fiber per ct. : 17.5

N-free extract per ct. : 12.6

Total minerals per ct. : 2.9

Calcium per ct. : —

Phosphorus per ct. : 0.33

Nitrogen per ct. : 3.98

Potassium per ct. : 0.53

Material : Perilla oil meal

Total dry matter per ct. : 91.9

Protein per ct. : 38.4

Fat per ct. : 8.4

Fiber per ct. : 20.9

N-free extract per ct. : 16.0

Total minerals per ct. : 8.2

Calcium per ct. : 0.56

Phosphorus per ct. : 0.47

Nitrogen per ct. : 6.14

Potassium per ct. : —

Material : Pigeon-grass seed

Total dry matter per ct. : 89.8

Protein per ct. : 14.4

Fat per ct. : 6.0

Fiber per ct. : 17.3

N-free extract per ct. : 45.8

Total minerals per ct. : 6.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.30

Potassium per ct. : —

Material : Pigweed seed

Total dry matter per ct. : 90.0

Protein per ct. : 16.8

Fat per ct. : 6.2

Fiber per ct. : 15.9

N-free extract per ct. : 47.8

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.69

Potassium per ct. : —

Material : Pineapple bran, or pulp, dried

Total dry matter per ct. : 85.3

Protein per ct. : 4.0

Fat per ct. : 1.9

Fiber per ct. : 19.4

N-free extract per ct. : 57.2

Total minerals per ct. : 2.8

Calcium per ct. : 0.20

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.64

Potassium per ct. : —

Material : Pineapple bran, or pulp, and molasses, dried

Total dry matter per ct. : 87.4

Protein per ct. : 3.9

Fat per ct. : 1.0

Fiber per ct. : 15.9

N-free extract per ct. : 63.4

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.62

Potassium per ct. : —

Material : Poppy-seed oil meal

Total dry matter per ct. : 89.2

Protein per ct. : 36.6

Fat per ct. : 7.9

Fiber per ct. : 11.6

N-free extract per ct. : 20.7

Total minerals per ct. : 12.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.86

Potassium per ct. : —

Material : Potato meal, or dried potatoes

Total dry matter per ct. : 92.8

Protein per ct. : 10.4

Fat per ct. : 0.3

Fiber per ct. : 2.0

N-free extract per ct. : 75.8

Total minerals per ct. : 4.3

Calcium per ct. : 0.08

Phosphorus per ct. : 0.22

Nitrogen per ct. : 1.66

Potassium per ct. : 1.97

Material : Potato pomace, dried

Total dry matter per ct. : 89.1

Protein per ct. : 6.6

Fat per ct. : 0.5

Fiber per ct. : 10.3

N-free extract per ct. : 69.0

Total minerals per ct. : 2.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.06

Potassium per ct. : —

Material : Pumpkin seed, not dried

Total dry matter per ct. : 55.0

Protein per ct. : 17.6

Fat per ct. : 20.6

Fiber per ct. : 10.8

N-free extract per ct. : 4.1

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.82

Potassium per ct. : —

Material : Raisin pulp, dried

Total dry matter per ct. : 89.4

Protein per ct. : 9.6

Fat per ct. : 7.8

Fiber per ct. : 16.1

N-free extract per ct. : 50.6

Total minerals per ct. : 5.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.54

Potassium per ct. : —

Material : Raisins, cull

Total dry matter per ct. : 84.8

Protein per ct. : 3.4

Fat per ct. : 0.9

Fiber per ct. : 4.4

N-free extract per ct. : 73.1

Total minerals per ct. : 3.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.54

Potassium per ct. : —

Material : Rape seed

Total dry matter per ct. : 90.5

Protein per ct. : 20.4

Fat per ct. : 43.6

Fiber per ct. : 6.6

N-free extract per ct. : 15.7

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.26

Potassium per ct. : —

Material : Rape-seed oil meal

Total dry matter per ct. : 89.5

Protein per ct. : 33.5

Fat per ct. : 8.1

Fiber per ct. : 10.8

N-free extract per ct. : 30.2

Total minerals per ct. : 6.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.36

Potassium per ct. : —

Material : Rice, brewers’

Total dry matter per ct. : 88.3

Protein per ct. : 7.5

Fat per ct. : 0.6

Fiber per ct. : 0.6

N-free extract per ct. : 78.8

Total minerals per ct. : 0.8

Calcium per ct. : 0.04

Phosphorus per ct. : 0.10

Nitrogen per ct. : 1.20

Potassium per ct. : —

Material : Rice, brown

Total dry matter per ct. : 87.8

Protein per ct. : 9.1

Fat per ct. : 2.0

Fiber per ct. : 1.1

N-free extract per ct. : 74.5

Total minerals per ct. : 1.1

Calcium per ct. : 0.04

Phosphorus per ct. : 0.25

Nitrogen per ct. : 1.46

Potassium per ct. : —

Material : Rice, polished

Total dry matter per ct. : 87.8

Protein per ct. : 7.4

Fat per ct. : 0.4

Fiber per ct. : 0.4

N-free extract per ct. : 79.1

Total minerals per ct. : 0.5

Calcium per ct. : 0.01

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.18

Potassium per ct. : 0.04

Material : Rice bran

Total dry matter per ct. : 90.9

Protein per ct. : 12.5

Fat per ct. : 13.5

Fiber per ct. : 12.0

N-free extract per ct. : 39.4

Total minerals per ct. : 13.5

Calcium per ct. : 0.08

Phosphorus per ct. : 1.36

Nitrogen per ct. : 2.00

Potassium per ct. : 1.08

Material : Rice grain, or rough rice

Total dry matter per ct. : 88.8

Protein per ct. : 7.9

Fat per ct. : 1.8

Fiber per ct. : 9.0

N-free extract per ct. : 64.9

Total minerals per ct. : 5.2

Calcium per ct. : 0.08

Phosphorus per ct. : 0.32

Nitrogen per ct. : 1.26

Potassium per ct. : 0.34

Material : Rice polishings, or rice polish

Total dry matter per ct. : 89.8

Protein per ct. : 12.8

Fat per ct. : 13.2

Fiber per ct. : 2.8

N-free extract per ct. : 51.4

Total minerals per ct. : 9.6

Calcium per ct. : 0.04

Phosphorus per ct. : 1.10

Nitrogen per ct. : 2.04

Potassium per ct. : 1.17

Material : Rubber seed oil meal

Total dry matter per ct. : 91.1

Protein per ct. : 28.8

Fat per ct. : 9.2

Fiber per ct. : 10.0

N-free extract per ct. : 37.6

Total minerals per ct. : 5.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.61

Potassium per ct. : —

Material : Rye grain

Total dry matter per ct. : 89.5

Protein per ct. : 12.6

Fat per ct. : 1.7

Fiber per ct. : 2.4

N-free extract per ct. : 70.9

Total minerals per ct. : 1.9

Calcium per ct. : 0.10

Phosphorus per ct. : 0.33

Nitrogen per ct. : 2.02

Potassium per ct. : 0.47

Material : Rye feed

Total dry matter per ct. : 90.4

Protein per ct. : 16.1

Fat per ct. : 3.3

Fiber per ct. : 4.6

N-free extract per ct. : 62.7

Total minerals per ct. : 3.7

Calcium per ct. : 0.08

Phosphorus per ct. : 0.69

Nitrogen per ct. : 2.58

Potassium per ct. : 0.83

Material : Rye flour

Total dry matter per ct. : 88.6

Protein per ct. : 11.2

Fat per ct. : 1.3

Fiber per ct. : 0.6

N-free extract per ct. : 74.6

Total minerals per ct. : 0.9

Calcium per ct. : 0.02

Phosphorus per ct. : 0.28

Nitrogen per ct. : 11.279

Potassium per ct. : 0.46

Material : Rye flour middlings

Total dry matter per ct. : 90.6

Protein per ct. : 16.5

Fat per ct. : 3.5

Fiber per ct. : 4.2

N-free extract per ct. : 63.1

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.64

Potassium per ct. : —

Material : Rye middlings

Total dry matter per ct. : 90.2

Protein per ct. : 16.6

Fat per ct. : 3.4

Fiber per ct. : 5.2

N-free extract per ct. : 61.2

Total minerals per ct. : 3.8

Calcium per ct. : —

Phosphorus per ct. : 0.44

Nitrogen per ct. : 2.66

Potassium per ct. : 0.63

Material : Rye middlings and screenings

Total dry matter per ct. : 90.4

Protein per ct. : 16.7

Fat per ct. : 3.8

Fiber per ct. : 6.1

N-free extract per ct. : 59.5

Total minerals per ct. : 4.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.67

Potassium per ct. : —

Material : Safflower seed

Total dry matter per ct. : 93.1

Protein per ct. : 16.3

Fat per ct. : 29.8

Fiber per ct. : 26.6

N-free extract per ct. : 17.5

Total minerals per ct. : 2.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.61

Potassium per ct. : —

Material : Safflower seed oil meal, from hulled seed

Total dry matter per ct. : 91.0

Protein per ct. : 38.0

Fat per ct. : 6.8

Fiber per ct. : 21.0

N-free extract per ct. : 17.0

Total minerals per ct. : 8.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.08

Potassium per ct. : —

Material : Safflower-seed oil meal from unhulled seed

Total dry matter per ct. : 91.0

Protein per ct. : 18.2

Fat per ct. : 5.5

Fiber per ct. : 40.4

N-free extract per ct. : 24.1

Total minerals per ct. : 2.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.91

Potassium per ct. : —

Material : Sagrain sorghum grain

Total dry matter per ct. : 90.0

Protein per ct. : 9.5

Fat per ct. : 3.5

Fiber per ct. : 2.1

N-free extract per ct. : 73.4

Total minerals per ct. : 1.5

Calcium per ct. : 0.43

Phosphorus per ct. : 0.39

Nitrogen per ct. : 1.52

Potassium per ct. : —

Material : Screenings, grain, good grade

Total dry matter per ct. : 90.0

Protein per ct. : 15.8

Fat per ct. : 5.2

Fiber per ct. : 9.2

N-free extract per ct. : 54.3

Total minerals per ct. : 5.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.53

Potassium per ct. : —

Material : Screenings, grain, chaffy

Total dry matter per ct. : 91.5

Protein per ct. : 14.3

Fat per ct. : 4.4

Fiber per ct. : 18.3

N-free extract per ct. : 46.1

Total minerals per ct. : 8.4

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.29

Potassium per ct. : —

Material : Schrock sorghum grain

Total dry matter per ct. : 89.1

Protein per ct. : 10.2

Fat per ct. : 3.0

Fiber per ct. : 3.4

N-free extract per ct. : 70.8

Total minerals per ct. : 1.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.63

Potassium per ct. : —

Material : Sesame oil meal

Total dry matter per ct. : 93.7

Protein per ct. : 42.8

Fat per ct. : 9.4

Fiber per ct. : 6.2

N-free extract per ct. : 22.8

Total minerals per ct. : 12.5

Calcium per ct. : 2.02

Phosphorus per ct. : 1.61

Nitrogen per ct. : 6.84

Potassium per ct. : 1.35

Material : Sesbania seed

Total dry matter per ct. : 90.8

Protein per ct. : 31.7

Fat per ct. : 4.3

Fiber per ct. : 13.5

N-free extract per ct. : 38.0

Total minerals per ct. : 3.3

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.07

Potassium per ct. : —

Material : Shallu grain

Total dry matter per ct. : 89.8

Protein per ct. : 13.4

Fat per ct. : 3.7

Fiber per ct. : 1.9

N-free extract per ct. : 68.9

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.14

Potassium per ct. : —

Material : Shallu head chops

Total dry matter per ct. : 90.5

Protein per ct. : 12.7

Fat per ct. : 3.5

Fiber per ct. : 9.2

N-free extract per ct. : 61.9

Total minerals per ct. : 3.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.03

Potassium per ct. : —

Material : Shark meal

Total dry matter per ct. : 91.2

Protein per ct. : 74.5

Fat per ct. : 2.7

Fiber per ct. : 0.5

N-free extract per ct. : 0

Total minerals per ct. : 13.5

Calcium per ct. : 3.48

Phosphorus per ct. : 1.92

Nitrogen per ct. : 12.69

Potassium per ct. : —

Material : Shrimp meal

Total dry matter per ct. : 89.7

Protein per ct. : 46.7

Fat per ct. : 2.8

Fiber per ct. : 11.1

N-free extract per ct. : 1.3

Total minerals per ct. : 27.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.47

Potassium per ct. : —

Material : Skimmilk, centrifugal

Total dry matter per ct. : 9.5

Protein per ct. : 3.6

Fat per ct. : 0.1

Fiber per ct. : 0

N-free extract per ct. : 5.1

Total minerals per ct. : 0.7

Calcium per ct. : 0.13

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.58

Potassium per ct. : 0.15

Material : Skimmilk, gravity

Total dry matter per ct. : 10.1

Protein per ct. : 3.6

Fat per ct. : 0.8

Fiber per ct. : 0

N-free extract per ct. : 5.0

Total minerals per ct. : 0.7

Calcium per ct. : 0.13

Phosphorus per ct. : 0.10

Nitrogen per ct. : 0.58

Potassium per ct. : 0.15

Material : Skimmilk, dried

Total dry matter per ct. : 94.2

Protein per ct. : 34.7

Fat per ct. : 1.2

Fiber per ct. : 0.2

N-free extract per ct. : 50.3

Total minerals per ct. : 7.8

Calcium per ct. : 1.30

Phosphorus per ct. : 1.03

Nitrogen per ct. : 5.56

Potassium per ct. : 1.46

Material : Sorghum seed, sweet

Total dry matter per ct. : 89.2

Protein per ct. : 9.5

Fat per ct. : 3.3

Fiber per ct. : 2.0

N-free extract per ct. : 72.8

Total minerals per ct. : 1.6

Calcium per ct. : 0.02

Phosphorus per ct. : 0.28

Nitrogen per ct. : 1.52

Potassium per ct. : 0.37

Material : Soybean seed

Total dry matter per ct. : 90.0

Protein per ct. : 37.9

Fat per ct. : 18.0

Fiber per ct. : 5.0

N-free extract per ct. : 24.5

Total minerals per ct. : 4.6

Calcium per ct. : 0.25

Phosphorus per ct. : 0.59

Nitrogen per ct. : 6.06

Potassium per ct. : 1.50

Material : Soybean flour, medium in fat

Total dry matter per ct. : 92.9

Protein per ct. : 47.9

Fat per ct. : 6.7

Fiber per ct. : 2.4

N-free extract per ct. : 29.9

Total minerals per ct. : 6.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.66

Potassium per ct. : —

Material : Soybean flour, solvent extracted

Total dry matter per ct. : 91.5

Protein per ct. : 48.5

Fat per ct. : 0.8

Fiber per ct. : 2.6

N-free extract per ct. : 33.0

Total minerals per ct. : 6.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 7.76

Potassium per ct. : —

Material : Soybean mill feed, chiefly hulls

Total dry matter per ct. : 90.8

Protein per ct. : 11.8

Fat per ct. : 2.7

Fiber per ct. : 34.0

N-free extract per ct. : 38.1

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.89

Potassium per ct. : —

Material : Soybean oil meal, expeller or hydraulic process, all analyses

Total dry matter per ct. : 90.0

Protein per ct. : 44.3

Fat per ct. : 5.3

Fiber per ct. : 5.7

N-free extract per ct. : 29.6

Total minerals per ct. : 6.0

Calcium per ct. : 0.29

Phosphorus per ct. : 0.66

Nitrogen per ct. : 7.09

Potassium per ct. : 1.77

Material : Soybean oil meal, exp. or hydr. process, 44-45% protein guarantee

Total dry matter per ct. : 91.3

Protein per ct. : 45.4

Fat per ct. : 5.3

Fiber per ct. : 5.4

N-free extract per ct. : 29.3

Total minerals per ct. : 5.9

Calcium per ct. : 0.31

Phosphorus per ct. : 0.68

Nitrogen per ct. : 7.26

Potassium per ct. : 1.92

Material : Soybean oil meal, exp. or hydr. process, 43% protein guarantee

Total dry matter per ct. : 91.2

Protein per ct. : 44.6

Fat per ct. : 5.3

Fiber per ct. : 5.8

N-free extract per ct. : 29.4

Total minerals per ct. : 6.1

Calcium per ct. : 0.30

Phosphorus per ct. : 0.67

Nitrogen per ct. : 7.14

Potassium per ct. : —

Material : Soybean oil meal, exp. or hydr. process, 41% protein guarantee

Total dry matter per ct. : 90.9

Protein per ct. : 44.2

Fat per ct. : 5.3

Fiber per ct. : 5.7

N-free extract per ct. : 29.7

Total minerals per ct. : 6.0

Calcium per ct. : 0.26

Phosphorus per ct. : 0.59

Nitrogen per ct. : 7.07

Potassium per ct. : —

Material : Soybean oil meal, solvent process

Total dry matter per ct. : 90.6

Protein per ct. : 46.1

Fat per ct. : 1.0

Fiber per ct. : 5.9

N-free extract per ct. : 31.8

Total minerals per ct. : 5.8

Calcium per ct. : 0.30

Phosphorus per ct. : 0.66

Nitrogen per ct. : 7.38

Potassium per ct. : 1.92

Material : Starfish meal

Total dry matter per ct. : 96.5

Protein per ct. : 30.6

Fat per ct. : 5.8

Fiber per ct. : 1.9

N-free extract per ct. : 14.3

Total minerals per ct. : 43.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.90

Potassium per ct. : —

Material : Sudan-grass seed

Total dry matter per ct. : 92.4

Protein per ct. : 14.2

Fat per ct. : 2.4

Fiber per ct. : 25.4

N-free extract per ct. : 38.4

Total minerals per ct. : 12.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.27

Potassium per ct. : —

Material : Sunflower seed

Total dry matter per ct. : 93.6

Protein per ct. : 16.8

Fat per ct. : 25.9

Fiber per ct. : 29.0

N-free extract per ct. : 18.8

Total minerals per ct. : 3.1

Calcium per ct. : —

Phosphorus per ct. : 0.55

Nitrogen per ct. : 2.69

Potassium per ct. : 0.66

Material : Sunflower seed, hulled

Total dry matter per ct. : 95.5

Protein per ct. : 27.7

Fat per ct. : 41.4

Fiber per ct. : 6.3

N-free extract per ct. : 16.3

Total minerals per ct. : 3.8

Calcium per ct. : 0.20

Phosphorus per ct. : 0.96

Nitrogen per ct. : 4.43

Potassium per ct. : 0.92

Material : Sunflower-seed oil cake, from unhulled seed, solvent process

Total dry matter per ct. : 89.2

Protein per ct. : 19.6

Fat per ct. : 1.1

Fiber per ct. : 35.9

N-free extract per ct. : 27.0

Total minerals per ct. : 5.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.14

Potassium per ct. : —

Material : Sunflower-seed oil cake, from hulled seed, hydr. process

Total dry matter per ct. : 90.6

Protein per ct. : 36.3

Fat per ct. : 13.5

Fiber per ct. : 14.2

N-free extract per ct. : 20.2

Total minerals per ct. : 6.4

Calcium per ct. : 0.43

Phosphorus per ct. : 1.04

Nitrogen per ct. : 5.81

Potassium per ct. : 1.08

Material : Sweet clover seed

Total dry matter per ct. : 92.2

Protein per ct. : 37.4

Fat per ct. : 4.2

Fiber per ct. : 11.3

N-free extract per ct. : 35.8

Total minerals per ct. : 3.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 5.98

Potassium per ct. : —

Material : Sweet potatoes, dried

Total dry matter per ct. : 90.3

Protein per ct. : 4.9

Fat per ct. : 0.9

Fiber per ct. : 3.3

N-free extract per ct. : 77.1

Total minerals per ct. : 4.1

Calcium per ct. : 0.21

Phosphorus per ct. : 0.18

Nitrogen per ct. : 0.78

Potassium per ct. : —

Material : Tankage or meat meal, digester process, 60% protein grade

Total dry matter per ct. : 93.1

Protein per ct. : 60.6

Fat per ct. : 8.5

Fiber per ct. : 2.0

N-free extract per ct. : 1.8

Total minerals per ct. : 20.2

Calcium per ct. : 6.37

Phosphorus per ct. : 3.23

Nitrogen per ct. : 9.70

Potassium per ct. : 0.46

Material : Tankage with bone, or meat and bone meal, digester process, 50% protein grade

Total dry matter per ct. : 93.5

Protein per ct. : 51.3

Fat per ct. : 11.5

Fiber per ct. : 2.3

N-free extract per ct. : 2.3

Total minerals per ct. : 26.1

Calcium per ct. : 10.97

Phosphorus per ct. : 5.14

Nitrogen per ct. : 8.21

Potassium per ct. : —

Material : Tankage with bone, or meat and bone meal, digester process, 40% protein grade

Total dry matter per ct. : 94.7

Protein per ct. : 42.9

Fat per ct. : 14.1

Fiber per ct. : 2.2

N-free extract per ct. : 4.1

Total minerals per ct. : 31.4

Calcium per ct. : 13.49

Phosphorus per ct. : 5.18

Nitrogen per ct. : 6.86

Potassium per ct. : —

Material : Tomato pomace, dried

Total dry matter per ct. : 94.6

Protein per ct. : 22.9

Fat per ct. : 15.0

Fiber per ct. : 30.2

N-free extract per ct. : 23.4

Total minerals per ct. : 3.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.66

Potassium per ct. : —

Material : Velvet bean seeds and pods (velvet bean feed)

Total dry matter per ct. : 90.0

Protein per ct. : 18.1

Fat per ct. : 4.4

Fiber per ct. : 13.0

N-free extract per ct. : 50.3

Total minerals per ct. : 4.2

Calcium per ct. : 0.24

Phosphorus per ct. : 0.38

Nitrogen per ct. : 2.90

Potassium per ct. : 1.20

Material : Velvet beans, seeds only

Total dry matter per ct. : 90.0

Protein per ct. : 23.4

Fat per ct. : 5.7

Fiber per ct. : 6.4

N-free extract per ct. : 51.5

Total minerals per ct. : 3.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 3.74

Potassium per ct. : —

Material : Vetch seed

Total dry matter per ct. : 90.7

Protein per ct. : 29.6

Fat per ct. : 0.8

Fiber per ct. : 5.7

N-free extract per ct. : 51.5

Total minerals per ct. : 3.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.74

Potassium per ct. : —

Material : Whale meal

Total dry matter per ct. : 91.8

Protein per ct. : 78.5

Fat per ct. : 6.7

Fiber per ct. : 0

N-free extract per ct. : 3.1

Total minerals per ct. : 3.5

Calcium per ct. : 0.56

Phosphorus per ct. : 0.57

Nitrogen per ct. : 12.56

Potassium per ct. : —

Material : Wheat, average of all types

Total dry matter per ct. : 89.5

Protein per ct. : 13.2

Fat per ct. : 1.9

Fiber per ct. : 2.6

N-free extract per ct. : 69.9

Total minerals per ct. : 1.9

Calcium per ct. : 0.04

Phosphorus per ct. : 0.39

Nitrogen per ct. : 2.11

Potassium per ct. : 0.42

Material : Wheat, hard spring, chiefly northern plains states

Total dry matter per ct. : 90.1

Protein per ct. : 15.8

Fat per ct. : 2.2

Fiber per ct. : 2.5

N-free extract per ct. : 67.8

Total minerals per ct. : 1.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.53

Potassium per ct. : —

Material : Wheat, hard winter, chiefly southern plains states

Total dry matter per ct. : 89.4

Protein per ct. : 13.5

Fat per ct. : 1.8

Fiber per ct. : 2.8

N-free extract per ct. : 69.2

Total minerals per ct. : 2.1

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.16

Potassium per ct. : —

Material : Wheat, soft winter, Miss. valley and eastward

Total dry matter per ct. : 89.2

Protein per ct. : 10.2

Fat per ct. : 1.9

Fiber per ct. : 2.1

N-free extract per ct. : 73.2

Total minerals per ct. : 1.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.63

Potassium per ct. : —

Material : Wheat, soft, Pacific Coast states

Total dry matter per ct. : 89.1

Protein per ct. : 9.9

Fat per ct. : 2.0

Fiber per ct. : 2.7

N-free extract per ct. : 72.6

Total minerals per ct. : 1.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.58

Potassium per ct. : —

Material : Wheat bran, all analyses

Total dry matter per ct. : 90.1

Protein per ct. : 16.9

Fat per ct. : 4.6

Fiber per ct. : 9.6

N-free extract per ct. : 52.9

Total minerals per ct. : 6.1

Calcium per ct. : 0.14

Phosphorus per ct. : 1.29

Nitrogen per ct. : 2.70

Potassium per ct. : 1.23

Material : Wheat bran, chiefly hard spring wheat

Total dry matter per ct. : 91.1

Protein per ct. : 17.9

Fat per ct. : 4.9

Fiber per ct. : 10.1

N-free extract per ct. : 52.2

Total minerals per ct. : 6.1

Calcium per ct. : 0.13

Phosphorus per ct. : 1.35

Nitrogen per ct. : 2.86

Potassium per ct. : —

Material : Wheat bran, soft wheat

Total dry matter per ct. : 90.5

Protein per ct. : 16.1

Fat per ct. : 4.3

Fiber per ct. : 8.7

N-free extract per ct. : 55.7

Total minerals per ct. : 5.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.58

Potassium per ct. : —

Material : Wheat bran, winter wheat

Total dry matter per ct. : 89.9

Protein per ct. : 15.5

Fat per ct. : 4.2

Fiber per ct. : 8.9

N-free extract per ct. : 55.1

Total minerals per ct. : 6.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.48

Potassium per ct. : —

Material : Wheat bran and screenings, all analyses

Total dry matter per ct. : 90.0

Protein per ct. : 16.8

Fat per ct. : 4.5

Fiber per ct. : 9.6

N-free extract per ct. : 53.0

Total minerals per ct. : 6.1

Calcium per ct. : 0.14

Phosphorus per ct. : 1.21

Nitrogen per ct. : 2.69

Potassium per ct. : —

Material : Wheat brown shorts

Total dry matter per ct. : 88.7

Protein per ct. : 16.9

Fat per ct. : 4.2

Fiber per ct. : 7.1

N-free extract per ct. : 56.0

Total minerals per ct. : 4.5

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.70

Potassium per ct. : —

Material : Wheat brown shorts and screenings

Total dry matter per ct. : 88.7

Protein per ct. : 17.0

Fat per ct. : 4.1

Fiber per ct. : 7.0

N-free extract per ct. : 56.0

Total minerals per ct. : 4.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.72

Potassium per ct. : —

Material : Wheat flour, graham

Total dry matter per ct. : 88.1

Protein per ct. : 12.5

Fat per ct. : 1.9

Fiber per ct. : 1.8

N-free extract per ct. : 70.4

Total minerals per ct. : 1.5

Calcium per ct. : 0.04

Phosphorus per ct. : 0.36

Nitrogen per ct. : 2.00

Potassium per ct. : 0.46

Material : Wheat flour, low grade

Total dry matter per ct. : 88.4

Protein per ct. : 15.4

Fat per ct. : 1.9

Fiber per ct. : 0.5

N-free extract per ct. : 69.7

Total minerals per ct. : 0.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.46

Potassium per ct. : —

Material : Wheat flour, white

Total dry matter per ct. : 88.0

Protein per ct. : 10.8

Fat per ct. : 0.9

Fiber per ct. : 0.3

N-free extract per ct. : 75.6

Total minerals per ct. : 0.4

Calcium per ct. : 0.02

Phosphorus per ct. : 0.09

Nitrogen per ct. : 1.73

Potassium per ct. : 0.05

Material : Wheat flour middlings

Total dry matter per ct. : 89.2

Protein per ct. : 18.3

Fat per ct. : 4.2

Fiber per ct. : 3.8

N-free extract per ct. : 59.8

Total minerals per ct. : 3.1

Calcium per ct. : 0.09

Phosphorus per ct. : 0.71

Nitrogen per ct. : 2.93

Potassium per ct. : 0.89

Material : Wheat flour middlings and screenings

Total dry matter per ct. : 89.6

Protein per ct. : 18.2

Fat per ct. : 4.5

Fiber per ct. : 5.2

N-free extract per ct. : 57.8

Total minerals per ct. : 3.9

Calcium per ct. : 0.14

Phosphorus per ct. : 0.68

Nitrogen per ct. : 2.91

Potassium per ct. : —

Material : Wheat germ meal, commercial

Total dry matter per ct. : 90.8

Protein per ct. : 31.1

Fat per ct. : 9.7

Fiber per ct. : 2.6

N-free extract per ct. : 42.2

Total minerals per ct. : 5.2

Calcium per ct. : 0.08

Phosphorus per ct. : 1.11

Nitrogen per ct. : 4.98

Potassium per ct. : 0.29

Material : Wheat germ oil meal

Total dry matter per ct. : 89.1

Protein per ct. : 30.4

Fat per ct. : 4.9

Fiber per ct. : 2.6

N-free extract per ct. : 46.4

Total minerals per ct. : 4.8

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 4.86

Potassium per ct. : —

Material : Wheat gray shorts

Total dry matter per ct. : 88.9

Protein per ct. : 17.9

Fat per ct. : 4.2

Fiber per ct. : 5.7

N-free extract per ct. : 56.9

Total minerals per ct. : 4.2

Calcium per ct. : 0.13

Phosphorus per ct. : 0.84

Nitrogen per ct. : 2.86

Potassium per ct. : —

Material : Wheat gray shorts and screenings

Total dry matter per ct. : 88.6

Protein per ct. : 17.6

Fat per ct. : 4.0

Fiber per ct. : 5.8

N-free extract per ct. : 57.0

Total minerals per ct. : 4.2

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.82

Potassium per ct. : —

Material : Wheat mixed feed, all analyses

Total dry matter per ct. : 89.7

Protein per ct. : 17.2

Fat per ct. : 4.5

Fiber per ct. : 7.2

N-free extract per ct. : 56.1

Total minerals per ct. : 4.7

Calcium per ct. : 0.11

Phosphorus per ct. : 1.09

Nitrogen per ct. : 2.76

Potassium per ct. : —

Material : Wheat mixed feed, hard wheat

Total dry matter per ct. : 89.8

Protein per ct. : 18.7

Fat per ct. : 4.8

Fiber per ct. : 7.7

N-free extract per ct. : 53.6

Total minerals per ct. : 5.0

Calcium per ct. : 0.11

Phosphorus per ct. : 1.09

Nitrogen per ct. : 2.99

Potassium per ct. : —

Material : Wheat mixed feed and screenings

Total dry matter per ct. : 89.3

Protein per ct. : 17.5

Fat per ct. : 4.3

Fiber per ct. : 7.1

N-free extract per ct. : 55.7

Total minerals per ct. : 4.7

Calcium per ct. : 0.11

Phosphorus per ct. : 0.96

Nitrogen per ct. : 2.80

Potassium per ct. : —

Material : Wheat red dog

Total dry matter per ct. : 89.0

Protein per ct. : 18.2

Fat per ct. : 3.6

Fiber per ct. : 2.6

N-free extract per ct. : 61.9

Total minerals per ct. : 2.7

Calcium per ct. : 0.07

Phosphorus per ct. : 0.51

Nitrogen per ct. : 2.91

Potassium per ct. : 0.60

Material : Wheat red dog, low grade

Total dry matter per ct. : 89.2

Protein per ct. : 17.9

Fat per ct. : 4.8

Fiber per ct. : 4.9

N-free extract per ct. : 57.9

Total minerals per ct. : 3.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.86

Potassium per ct. : —

Material : Wheat screenings, good grade

Total dry matter per ct. : 90.4

Protein per ct. : 13.9

Fat per ct. : 4.7

Fiber per ct. : 9.0

N-free extract per ct. : 58.2

Total minerals per ct. : 4.6

Calcium per ct. : 0.44

Phosphorus per ct. : 0.39

Nitrogen per ct. : 2.22

Potassium per ct. : —

Material : Wheat standard middlings, all analyses

Total dry matter per ct. : 89.6

Protein per ct. : 18.1

Fat per ct. : 4.8

Fiber per ct. : 6.5

N-free extract per ct. : 55.8

Total minerals per ct. : 4.4

Calcium per ct. : 0.09

Phosphorus per ct. : 0.93

Nitrogen per ct. : 2.90

Potassium per ct. : 1.04

Material : Wheat standard middlings and screenings, all analyses

Total dry matter per ct. : 89.7

Protein per ct. : 18.0

Fat per ct. : 4.7

Fiber per ct. : 7.4

N-free extract per ct. : 55.1

Total minerals per ct. : 4.5

Calcium per ct. : 0.15

Phosphorus per ct. : 0.88

Nitrogen per ct. : 2.88

Potassium per ct. : —

Material : Wheat white shorts

Total dry matter per ct. : 89.7

Protein per ct. : 16.1

Fat per ct. : 3.1

Fiber per ct. : 2.9

N-free extract per ct. : 65.0

Total minerals per ct. : 2.6

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.58

Potassium per ct. : —

Material : Whey, from cheddar cheese

Total dry matter per ct. : 6.9

Protein per ct. : 0.9

Fat per ct. : 0.3

Fiber per ct. : 0

N-free extract per ct. : 5.0

Total minerals per ct. : 0.7

Calcium per ct. : 0.05

Phosphorus per ct. : 0.04

Nitrogen per ct. : 0.14

Potassium per ct. : 0.19

Material : Whey, skimmed

Total dry matter per ct. : 6.6

Protein per ct. : 0.9

Fat per ct. : 0.03

Fiber per ct. : 0

N-free extract per ct. : 5.0

Total minerals per ct. : 0.7

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 0.14

Potassium per ct. : —

Material : Whey, condensed

Total dry matter per ct. : 57.3

Protein per ct. : 8.8

Fat per ct. : 0.6

Fiber per ct. : 0

N-free extract per ct. : 42.0

Total minerals per ct. : 5.9

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 1.41

Potassium per ct. : —

Material : Whey, dried

Total dry matter per ct. : 93.5

Protein per ct. : 12.2

Fat per ct. : 0.8

Fiber per ct. : 0.2

N-free extract per ct. : 70.4

Total minerals per ct. : 9.9

Calcium per ct. : 0.86

Phosphorus per ct. : 0.72

Nitrogen per ct. : 1.96

Potassium per ct. : —

Material : Whey solubles, dried

Total dry matter per ct. : 96.3

Protein per ct. : 17.5

Fat per ct. : 2.0

Fiber per ct. : 0

N-free extract per ct. : 62.8

Total minerals per ct. : 14.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 2.80

Potassium per ct. : —

Material : Yeast, brewers', dried

Total dry matter per ct. : 93.8

Protein per ct. : 49.3

Fat per ct. : 1.0

Fiber per ct. : 3.7

N-free extract per ct. : 31.9

Total minerals per ct. : 7.9

Calcium per ct. : 0.13

Phosphorus per ct. : 1.56

Nitrogen per ct. : 7.89

Potassium per ct. : —

Material : Yeast, irradiated, dried

Total dry matter per ct. : 93.9

Protein per ct. : 48.7

Fat per ct. : 1.1

Fiber per ct. : 5.5

N-free extract per ct. : 32.2

Total minerals per ct. : 6.4

Calcium per ct. : 0.07

Phosphorus per ct. : 1.55

Nitrogen per ct. : 7.79

Potassium per ct. : 2.14

Material : Yeast, dried, with added cereal

Total dry matter per ct. : 90.2

Protein per ct. : 12.3

Fat per ct. : 3.7

Fiber per ct. : 3.2

N-free extract per ct. : 68.5

Total minerals per ct. : 2.5

Calcium per ct. : 0.09

Phosphorus per ct. : 0.45

Nitrogen per ct. : 1.97

Potassium per ct. : —

Material : Yeast, molasses distillers', dried

Total dry matter per ct. : 91.0

Protein per ct. : 38.8

Fat per ct. : 1.9

Fiber per ct. : 6.1

N-free extract per ct. : 30.2

Total minerals per ct. : 14.0

Calcium per ct. : —

Phosphorus per ct. : —

Nitrogen per ct. : 6.21

Potassium per ct. : —

(These tables have been adapted from "U.S.-Canadian Tables of Feed Composition"; Publication 1684; Committee on Animal Nutrition and National Committee on Animal Nutrition, Canada, National Academy of Sciences—National Research Council, Washington, D.C. 1969)

Weights and Volumes

1 liter water = 1,000 ml = 1,000 grams = 1 kilogram = 2.205 lbs.

1 gallon water = 3,785 ml = 128 ounces = 3.785 liters = 8.34 lbs.

1 cubic foot water = 62.41 lbs. at 10°C

1 gallon = 4 quarts

1 quart = 4 cups = 32 fluid ounces

2 cups = .47 liters

1 cubic inch = 16.3872 cubic centimeters

1 cubic foot = .0283 cubic meters

1 cubic yard = .7646 cubic meters

1 cubic yard = 324 square feet 1 inch deep = 81 square feet 4 inches deep = 27 square feet 12 inches deep

1 cubic centimeter = .0610 cubic inches

1 cubic meter = 35.3145 cubic feet

1 cubic meter = 1.3079 cubic yards

1 pound = 16 ounces = .4536 kilograms = 454 grams

1 ounce = 28.35 grams

1 net ton = 2,000 pounds = .907 metric tons

1 metric ton = 1,000 kilograms

1 gross ton = 2,240 pounds = 1.016 tons

Temperature

0°K =	-273°C
F =	9/5 (C + 32)
C =	5/9 (F - 32)

0°C =	32°F
5°C =	41°F
10°C =	50°F
15°C =	59°F
20°C =	68°F
25°C =	77°F
30°C =	86°F
35°C =	95°F
40°C =	104°F
45°C =	113°F
50°C =	122°F
100°C =	212°F
200°C =	392°F
80°F =	26.7°C
90°F =	32.2°C
95°F =	35.0°C
100°F =	37.8°C
120°F =	48.9°C
140°F =	60.0°C
160°F =	71.1°C
180°F =	82.2°C
200°F =	93.4°C
0°F =	-17.8 C
5°F =	-15.5°C
10°F =	-12.2°C
15°F =	-9.4°C
20°F =	-6.7°C
25°F =	-3.9°C
30°F =	-1.1°C
35°F =	1.6°C
40°F =	4.4°C
45°F =	7.2 C
50°F =	10.0°C
60°F =	18.3°C
70°F =	21.2°C

Heat Energy

1 calorie = the heat energy to raise to 1 gram (1 ml) H₂O 1°C

1 BTU = 252 calories = the heat energy to raise 1 pound H₂O 1°F

Light

Pressure and Power

Miscellaneous Data

A

B

C

D

E

F

G

H

K

L

M

N

O

P

R

S

T

U

V

W

Black and white photographs

Color insert photographs

A

Abalone Mushroom. See Pleurotus cystidiosus

ABM. See Agaricus blazei

Adventures

A-frame culture

Agar media

cloning on

cultivation problems and solutions

culturing mycelium on

inoculating with spores

overview of culture technique

pouring

preparing nutrified

purifying cultures

sterilizing

volunteer primordia on, 13.1, 13.2

Agaria

Agaricales

Agaricales in Modern Taxonomy (Singer)

Agaricus (genus)

Agaricus arvensis (Horse)

Agaricus augustus (Prince), 3.1, 21.1, 21.2

Agaricus bisporus

Agaricus bitorquis

casing

as cultivation candidate

mycelial characteristics

taxonomy

Agaricus blazei (Himematsutake), 21.1, 21.2

agar culture media

available strains

casing

comments

common names

as cultivation candidate

description, 9.1, 21.1

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 19.2, 21.1

fruiting substrates

growth parameters

harvesting, 14.1, 21.1, 23.1

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

taxonomy

yield potentials

Agaricus brunnescens (Button or Portobello)

agar culture media

available strains

casing, 14.1, 20.1, 20.2

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 19.2, 19.3, 19.4, 19.5, 19.6, 21.1

fruiting substrates

growth parameters

harvesting, 21.1, 23.1

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nematodes

nutritional content

recipe

as secondary decomposer

spawn media

spore load

taxonomy

yield potentials

Agaricus campestris

Agaricus edodes

Agaricus hortensis

Agaricus lilaceps

Agaricus marmoreus

Agaricus pulmonarius

Agaricus Resource Program (ARP)

Agaricus subrufescens (Almond Agaricus), 3.1, 21.1, 21.2

Agaricus sylvicola

Agaricus tessulatus

Agaritines, 21.1, 21.2

Agricultural waste products

alternative treatment methods

fruiting formulas

heat-treating

Agrocybe (genus)

as tertiary decomposers

in wood chips

Agrocybe aegerita (Black Poplar)

agar culture media

available strains

casing

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 17.1, 21.1

growth parameters

harvesting, 21.1, 23.1

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

primordia formation, 13.1, 13.2

spawn media

spore-mass inoculation

taxonomy

yield potentials

Agrocybe arvalis

Agrocybe cylindracea

Agrocybe cylindrica

Agrocybe molesta

Agrocybe praecox

AIDS. See HIV/AIDS

Air exchange

fruitbody development and

importance of

primordia formation and

rate of

spawn run and

Air filtration, 10.1, 10.2, 11.1, 11.2, 25.1, 25.2

Albatrellus (genus)

Aleuria aurantia (Orange Peel)

Allergies

Almond Agaricus. See Agaricus subrufescens

Almond Portobello. See Agaricus blazei

Amanita (genus), 1.1, 1.2

Amanita muscaria (Fly Agaric), 1.1, 21.1

Anti-inflammatory agents

Antiviral medicines

Arabinoxylane

Aragekikurage. See Auricularia polytricha

Aristotle, 1.1, 1.2

Armillaria (genus)

Armillaria gallica

Armillaria mellea, 2.1, 4.1, 4.2, 13.1

Armillaria oystoyae

Aroma

Aromatase

Arora, David, 21.1, 24.1

Art

Ganoderma applanatum in, 21.1

Ganoderma lucidum in, 21.1, 21.2, 21.3

prehistoric

Trametes versicolor in, 21.1

Artist Conk. See Ganoderma applanatum

Associations and societies

growers, 25.1, 25.2

international, 25.1, 25.2

North American

Atmospheric sterilization

Auricularia auricula, 3.1, 4.1, 21.1, 21.2, 21.3

Auricularia cornea

Auricularia fuscosuccinea

Auricularia polytricha (Wood Ear), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 21.1

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

taxonomy

yield potentials

Autoclavable spawn bags

Autoclaves

choosing

cooling

equipping

placing

unloading

B

Baby Portobello. See Agaricus brunnescens

Bacillus thuringiensis

Bacterial infection

Bag culture

Banana plants

Basidia, 9.1, 21.1

B.E. See Biological efficiency

Bear’s Head. See Hericium erinaceus

Beech Mushroom. See Hypsizygus tessulatus

Bees

Bessette, Arleen and Alan

Beta-glucans, 21.1, 21.2, 21.3

Big Laughing Mushroom. See Gymnopilus spectabilis

Biodiversity

Biological efficiency

Bioremediation

Birch Polypores. See Piptoporus betulinus

Black Forest Mushroom. See Lentinula edodes

Black Morel. See Morchella angusticeps

Black Mushroom. See Lentinula edodes

Black pin molds

Black Poplar Mushroom. See Agrocybe aegerita

Black rot fungi

Blanco Bello. See Agaricus brunnescens

Bleach bath method

Blewit. See Lepista nuda

Blue Angels. See Psilocybe cyanescens

Boletus of the Steppes. See Pleurotus eryngii

Books

cookbooks

field guides

suppliers

Bottle culture

Breast cancer, 2.1, 21.1

Brick Top. See Hypholoma sublateritium

Bridgeoporus nobilissimus, 2.1, 21.1

Brooke-Webster, Davel

Brown Button Mushroom. See Agaricus brunnescens

Brown-Gilled Clustered Woodlover. See Hypholoma capnoides

BT-14

Buddha

Bug lights, 25.1, 25.2

Buna-shimeji. See Hypsizygus tessulatus

Burgundy Mushroom. See Stropharia rugosoannulata

Button mushrooms. See Agaricus brunnescens

By-products

C

Calcium/calcium sulfate, 17.1, 20.1, 21.1

Calvatia gigantea (Giant Puffball), 3.1

Cancer

Agaricus blazei and, 21.1

Agaricus brunnescens and, 21.1

Auricularia polytricha and, 21.1

Flammulina velutipes and, 21.1

Ganoderma lucidum and, 21.1

Grifola frondosa and, 21.1

Hericium erinaceus and, 21.1

Hypsizygus tessulatus and, 21.1

Hypsizygus ulmarius and, 21.1

Lentinula edodes and, 21.1

Pholiota nameko and, 21.1

Pleurotus ostreatus and, 21.1

Polyporus umbellatus and, 21.1, 21.2

Taxomyces andreanae and, 2.1

Trametes versicolor and, 21.1

Cantharellus cibarius (Chanterelle)

Cap margins

Cap orientation

Caramel Caps. See Psilocybe cyanescens

Carbon dioxide, 9.1, 14.1. See also Air exchange

Casing, 19.1, 19.2

Catastrophes, 2.1, 5.1, 21.1, 21.2

Cauliflower mushrooms

Cave culture, 25.1, 25.2

Chadwick, Kelly

Champignon. See Agaricus brunnescens

Chang, S. T.

Chang Jung-lieh

Chanterelles

Chapman, Bill

Cheilocystidia, 9.1, 9.2

Chestnut Mushroom. See Hypholoma sublateritium

Chicken-of-the-Woods. See Laetiporus sulphureus

Chilton, Jeff

Chinese Mushroom. See Lentinula edodes; Volvariella volvacea

Chinese Sclerotium. See Polyporus umbellatus

Chlamydospores

Cholesterol reduction, 21.1, 21.2, 21.3

Chorei-maitake. See Polyporus umbellatus

Chrysanthemum Mushroom. See Tremella fuciformis

Cinnamon Caps. See Hypholoma sublateritium

Clamp connections

Claudius II

Clavaire Cre’pue. See Sparassis crispa

Clement VII (pope)

Clitocybe (genus)

Cloning

starting strains by

wild vs. cultivated mushrooms

Cloud Mushroom. See Trametes versicolor

CMYA

Coffee waste, 6.1, 18.1, 18.2

Cogmelo de Deus. See Agaricus blazei

Cold shock, 14.1, 15.1

Collybia nameko

Collybia tuberosa

Collybia velutipes

Column culture

Composting, 5.1, 7.1

Conic Morel. See Morchella angusticeps

Conidiophores

Conocybe (genus)

Conocybe cyanopus

Consumption, per capita

Contamination

definition of

disposing of

minimizing

purifying cultures

vectors of, 10.1, 25.1

Conversion tables

Cookbooks. See also Recipes

Co-op marketing

Coprinus atramentarius

Coprinus comatus (Shaggy Mane), 21.1

agar culture media

available strains

casing

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 4.1, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nutritional content

in permaculture

spawn media

species sequencing, 4.1, 22.1

taxonomy

in wood chips

yield potentials

Coprinus disseminatus

Coprinus lagopus

Coprinus micaceus

Cordyceps subsessilis

Coremia, 9.1, 13.1

Coriolus versicolor

Corncobs

Cornmeal, Yeast, Glucose Agar (CMYA)

Cornstalks

Costantinella cristata, 21.1, 21.2

Cottonwoods

Coulter, Elsie

Crimini. See Agaricus brunnescens

Cropping containers

bag culture

bottle culture

column culture

slanted wall or A-frame culture

tray culture

vertical wall culture

Cultivation. See also Natural culture; individual techniques, substrates, and species

associations

overview of techniques, 11.1, 11.2

problems and solutions

selecting candidate for, 2.1, 3.1

seminars

Culture slants

Cultures. See also Strains

libraries

purifying

sources for

Cyans. See Psilocybe cyanescens

Cyclosporin

Cystidia

Czarnecki, Jack

D

Daedalea quercina

Dancing Butterfly Mushroom. See Grifola frondosa

Danell, Eric

Decontamination mats

Deden, Joe

Deer Mushroom. See Pluteus cervinus

Dehydrators

Demeter

Dendropolyporus umbellata

Detergent bath method

DFA, 12.1, 12.2

Dhingri. See Pleurotus pulmonarius

Dioscorides

Discinia perlata

Dog Food Agar (DFA), 12.1, 12.2

Donku. See Lentinula edodes

Drying

E

Ear Fungus. See Auricularia polytricha

Early Morel. See Verpa bohemica

Ectomycorrhizae, 2.1, 2.2

Edenshaw, Charles

Eleusinian Mysteries

Elm Oyster Mushroom. See Hypsizygus ulmarius

Elsie’s Edible. See Hypholoma capnoides

Emphysema, pulmonary

Endomycorrhizae

Enoki. See Flammulina velutipes

Enokitake. See Flammulina velutipes

Erinacines

Events

F

Facultative parasites

Fairy Ring Mushroom. See Marasmius oreades

False Morel. See Gyromitria esculenta

Fantasi-takes. See Psilocybe cyanescens

Festivals

Field guides

Filtration, . See also Air filtration; HEPA filters

Flamingo Mushroom. See Pleurotus djamor

Flammulin, 14.1, 21.1

Flammulina velutipes (Enoki), 21.1

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature, 13.1, 21.1

fruiting containers, 19.1, 19.2, 21.1

fruiting substrates, 17.1, 17.2, 21.1

growth parameters

harvesting

introduction

light and, 21.1, 21.2

marketed products

medicinal properties, 14.1, 21.1

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

in permaculture

primordia formation

spawn media

spoiling

spore-mass inoculation

on stumps

taxonomy, 21.1, 21.2

yield potentials

Flavor, . See also individual species

Flies, 25.1, 25.2, 25.3

Flushes, 7.1, 14.1

Fly Agaric. See Amanita muscaria

Fomes fomentarius, 1.1, 21.1, 21.2

Fomitopsis officinalis, 21.1, 21.2

Fragrance signature, . See also individual species

Frogs

Fruitbody development

Fruiting substrates. See also Agricultural waste products; Sawdust, enriched

analysis of basic materials for

coffee and banana plants

colonizing

corncobs and cornstalks

formulating, 11.1, 12.1

indoor vs. outdoor

materials for

maximizing potential of

paper products

seed hulls

soybean roughage (Okara)

sterilizing

straws

structure of

sugarcane bagasse

supplements

uneven inoculation of

wood

Fukuoka, Masanobu

Fukurotake. See Volvariella volvacea

Fuligo cristata (Vomited Scrambled Egg Fungus), 4.1

Furry Foot Collybia. See Flammulina velutipes

G

Gaines, Richard

Galerina autumnalis

on stumps

in wood chips

Ganoderma (genus)

mycelial characteristics

toxic waste and

Ganoderma applanatum, 21.1, 21.2

Ganoderma curtisii, 13.1, 21.1, 21.2, 21.3

Ganoderma japonicum

Ganoderma lucidum (Reishi), 21.1

agar culture media

in art, 21.1, 21.2, 21.3

available strains

casing

comments

common names

description

distribution

drying

flavor and cooking

fragrance signature

fruiting containers, 19.1, 19.2, 21.1

fruiting substrates, 6.1, 17.1, 21.1

growth parameters

harvesting

indoor cultivation

introduction

marketed products

medicinal properties, 21.1, 21.2, 21.3

microscopic features

moisture content

mycelial characteristics, 13.1, 13.2, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 4.2, 21.1, 21.2

natural habitat

nutritional content

in permaculture, 5.1, 5.2

photosensitivity, 14.1, 14.2

primordia formation, 13.1, 13.2

secondary metabolites

spawn media

species sequencing, 21.1, 22.1

spore load

spore-mass inoculation

on stumps

taxonomy

yield potentials

Ganoderma neo-japonicum

Ganoderma oregonense, 6.1, 21.1, 21.2, 21.3

Ganoderma sinense, 21.1, 21.2

Ganoderma tsugae, 6.1, 21.1, 21.2, 21.3

Garden Giant. See Stropharia rugosoannulata

Gartenriese. See Stropharia rugosoannulata

Germ pores, 9.1, 9.2

Giant Morel. See Morchella crassipes

Giant Puffball. See Calvatia gigantea

Gilled mushrooms, . See also individual species

Gloephyllum (genus)

Glove boxes

Godzilla Mushroom. See Stropharia rugosoannulata

Golden Ear Mushroom. See Tremella aurantia

Golden Mushroom. See Flammulina velutipes

Golden Oak Mushroom. See Lentinula edodes

Golden Oyster Mushroom. See Pleurotus citrinopileatus

Grain spawn

autoclavable bags for

containers for incubating

first-generation masters

formulas for creating

liquid-inoculation, 15.1, 15.2, 15.3

in outdoor substrates

overview of technique, 11.1, 11.2

preparing grain for

problems and solutions

second- and third-generation

spore-mass inoculation, 15.1, 15.2

Green-Gilled Clustered Woodlover. See Hypholoma fasciculare

Grifola frondosa (Maitake), 21.1

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature, 13.1, 21.1

frenzied dancing caused by

fruiting containers

fruiting substrates, 17.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties, 14.1, 21.1, 21.2

microscopic features

mycelial characteristics, 13.1, 13.2, 21.1

mycelial mass expansion, 21.1, 21.2

natural cultivation method

natural habitat

nutritional content

recipes, 24.1, 24.2, 24.3

spawn media

species sequencing, 21.1, 22.1

on stumps

taxonomy, 21.1, 21.2

yield potentials

Grifola umbellata, 21.1, 21.2

Grifolan, 14.1, 21.1

Growing room complex

air supply system

description of, 25.1, 25.2

designing and building

layout

managing

Growth parameters, . See also individual species

Guzman, Gaston

Gymnopilus luteofolius

Gymnopilus spectabilis (Big Laughing), 4.1, 21.1

Gypsum, 17.1, 20.1

Gyromitria esculenta (False Morel), 21.1

H

Haida, 21.1, 21.2

Half-free Morel. See Morchella semilibera

Harvesting, . See also individual species

problems and solutions

timing

Hearing degeneration

Heavy metals

Hedgehog Mushroom. See Hericium erinaceus

Heim, Roger, 1.1, 21.1

Hen-of-the-Woods. See Grifola frondosa

HEPA filters, 11.1, 11.2, 25.1

Hepatitis C

Hericium abietes, 21.1, 21.2

Hericium coralloides, 21.1, 21.2

Hericium erinaceus (Lion’s Mane), 21.1, 21.2

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 17.1, 17.2, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 13.2, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 4.2, 21.1

natural habitat

nutritional content

in permaculture

primordia formation, 13.1, 13.2

recipe

spawn media

species sequencing, 5.1, 21.1

speed of colonization

taxonomy

yield potentials

Hericium ramosum

Herpes simplex virus

High-pressure extrusion method

Himematsutake. See Agaricus blazei

Hiratake. See Pleurotus ostreatus

History

HIV/AIDS, 21.1, 21.2, 21.3, 21.4, 21.5

Hofmann, Albert

Hog Tuber Flowers

Homer

Honey mushrooms

Hon-shimeji, 21.1, 21.2, 21.3, 21.4, 24.1

Horse Mushroom. See Agaricus arvensis

Hot water bath method, 18.1, 18.2

Houtou. See Hericium erinaceus

Humidification

Hydnum erinaceum

Hydrated lime bath method

Hydrazines

Hydrogen peroxide technique

Hymenium

Hyphae, 9.1, 13.1

Hyphal aggregates, 13.1, 13.2

Hypholoma (genus), 4.1, 13.1, 21.1, 21.2, 22.1

Hypholoma capnoides (Brown-Gilled Woodlover), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 6.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nutritional content

in permaculture

spawn media

speed of colonization

taxonomy

in wood chips

yield potentials

Hypholoma fasciculare (Green-Gilled Clustered Woodlover), 21.1, 21.2

on stumps

in wood chips

Hypholoma sublateritium (Kuritake), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 17.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 13.2, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nutritional content

spawn media

speed of colonization

taxonomy

in wood chips

yield potentials

Hypholoma tuberosum

Hypoxylon archeri

Hypsizygus (genus), 4.1, 13.1, 21.1

Hypsizygus marmoreus, 21.1, 21.2

Hypsizygus tessulatus (Buna-shimeji), 21.1, 21.2

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 21.1

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

primordia formation

spawn media

taxonomy, 21.1, 21.2

yield potentials

Hypsizygus ulmarius (Shirotamogitake), 21.1, 21.2

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

in permaculture

primordia formation

spawn media

taxonomy, 21.1, 21.2

yield potentials

I

“Iceman,” 1–2

Il’mak. See Pleurotus citrinopileatus

Imazeki, R.

Immune system, stimulation of, 21.1, 21.2

Indian Oyster Mushroom. See Pleurotus pulmonarius

Initiation strategy, 9.1, 14.1, 21.1

Inoculation

contamination and

of enriched sawdust

of grain

liquid-, 15.1, 15.2, 15.3

loop, 12.1, 12.2

of outdoor substrates

rates, 4.1, 15.1

of sawdust

spore-mass, 4.1, 15.1, 15.2

Inonotus obliquus

Insects, 25.1, 25.2, 25.3

International Rules of Nomenclature

Internet resources

Isikhuemhen, Omon

J

Jelly mushrooms, . See also Tremella fuciformis

Journals

K

Karyogamy

Kawaratake. See Trametes versicolor

Kawariharatake. See Agaricus blazei

Kerrigan, Rick

Kikurage. See Auricularia polytricha

King Agaricus. See Agaricus blazei

King Oyster Mushroom. See Pleurotus eryngii

King Stropharia. See Stropharia rugosoannulata

King Tuber Oyster Mushroom. See Pleurotus tuberregium

Krestin

KS-2

Kumotake. See Grifola frondosa

Kuritake. See Hypholoma sublateritium

L

Laboratory

air filtration system

description of

designing and building

minimizing contamination in

Laetiporus sulphureus, 4.1, 5.1, 13.1, 13.2, 13.3, 21.1

Laissez-faire cultivation

Laminar flow benches, 12.1, 12.2

Laminar flow hood

Land-Fish mushrooms. See Morels

Lawyer’s Wig. See Coprinus comatus

Lentinan, 14.1, 21.1, 21.2

Lentinula (genus), 3.1, 21.1

Lentinula edodes (Shiitake), 21.1

agar culture media

agaritines in

available strains

calcium’s effect on, 17.1, 20.1, 21.1

comments

common names

as cultivation candidate

degeneration

description

distribution

drying, 23.1, 23.2

flavor and cooking, 14.1, 21.1, 24.1

fragrance signature, 13.1, 21.1

fruiting containers, 19.1, 21.1

fruiting substrates, 6.1, 12.1, 17.1, 17.2, 18.1, 21.1, 21.2

grades and prices

growth parameters

harvesting, 14.1, 21.1

introduction

market share

marketed products, 21.1, 23.1

medicinal properties, 14.1, 21.1, 21.2

microscopic features

moisture content

mycelial characteristics, 13.1, 13.2, 13.3, 14.1, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nutritional content

Oyster mushrooms vs.

in permaculture

photosensitivity

as primary decomposer

primordia formation

recipes, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7

spawn media

species sequencing, 4.1, 5.1, 21.1, 22.1

spore-mass inoculation

taxonomy

timing of crops

yield potentials

Lentinus dactyliophorus

Lentinus djamor

Lentinus edodes

Lentinus floridanus

Lentinus leucochrous

Lentinus sajor-caju

Lentinus squarrosulus, 21.1, 21.2

Lentinus tigrinus

Lentinus tuberregium

Lepiota (genus)

Lepiota naucina (Smooth Lepiota), 3.1

Lepiota procera (Parasol), 3.1

Lepiota rachodes (Scaly Lepiota), 3.1

Lepista nuda (Blewit), 3.1, 13.1, 14.1

Life cycle

Light

conversion tables

fruitbody development and, 21.1, 21.2

primordia formation and

sensitivity to

spawn run and

UV

Lincoff, Gary, 21.1, 21.2, 24.1

Lincoff, Irene

Ling Chi/Ling Chih/Ling Zhi. See Ganoderma lucidum

Lion’s Mane. See Hericium erinaceus

Liquid-inoculation, 15.1, 15.2, 15.3

Log culture, 4.1, 6.1, 21.1

Lonik, Larry

Lovastatin

Lung cancer, 21.1, 21.2, 21.3

Lyophyllum (genus)

Lyophyllum shimeji, 21.1, 21.2

Lyophyllum ulmarium

M

Macrocybe gigantea

Magic Mushrooms, 3.1, 13.1. See also individual species

Maitake. See Grifola frondosa

Malaria

Malt Extract Agar (MEA), 12.1, 12.2

Malt Extract, Yeast Agar (MYA)

Mannentake. See Ganoderma lucidum

Many-Colored Polypore. See Trametes versicolor

Maomuer. See Auricularia polytricha

Maotou-Guisan. See Coprinus comatus

Maple Oyster Mushroom. See Pleurotus cystidiosus

Marasmius oreades (Fairy Ring)

as cultivation candidate

mycelial characteristics

Marketing

co-op

information sources for

Matsutake, 2.1, 2.2, 2.3

McKenna, Terence

MCUs. See Mobile Contamination Units

MEA, 12.1, 12.2

Media, sterilizing

Medicinal products, sources for

Medicinal properties, 2.1, 14.1. See also individual species

Metabolites

Metals, 6.1, 14.1

Miller, Hope

Miller, Orson K., 21.1, 24.1

Miller’s Oyster Mushroom. See Pleurotus cystidiosus

Mimura, Shozaburo

Minerals

Mobile Contamination Units (MCUs)

Mo-er. See Auricularia polytricha

Moisture

fruitbody development and

primordia formation and

spawn run and

Mokurage. See Auricularia polytricha

Molds, 12.1, 13.1, 21.1, 25.1, 25.2

Mollison, Bill

Monilia

Monkey’s Head. See Hericium erinaceus

Moore, Scott and Alinde

Morchella angusticeps (Black Morel), 21.1, 21.2, 21.3

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 4.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

sclerotia, 13.1, 21.1

spawn media

taxonomy

yield potentials

Morchella atretomentosa

Morchella conica

Morchella crassipes (Giant Morel), 21.1, 21.2, 21.3

Morchella deliciosa

Morchella elata

Morchella esculenta (Yellow Morel), 4.1, 21.1, 21.2, 21.3, 21.4, 21.5

Morchella semilibera (Half-free Morel), 21.1

Morels, . See also individual species

degeneration

drying

fruiting substrates

indoor cultivation

life cycle

mycelial characteristics, 9.1, 14.1

nutrient deprivation and

in permaculture

recipes, 24.1, 24.2, 24.3

sclerotia

species sequencing, 4.1, 22.1

unusual fruitings

Morishige, Fukumi

Mu-er. See Auricularia polytricha

Muk Ngo. See Auricularia polytricha

Murrill, W. A.

Murrill’s Agaricus. See Agaricus blazei

Museums

Mushroom of God. See Agaricus blazei

Mushroom of the Gods. See Psilocybe cyanescens

Mushroom Response Teams (MRTs)

Mushroom stones, 1.1, 1.2, 1.3

Mushrooms in Their Natural Habitat (Smith)

Mutations

MYA

Mycelial capsule

Mycelial momentum

Mycelial network

Mycelium. See also Spawn

colors of, 13.1, 13.2

culturing, on agar media

definition of

dieback of

forms of

fragrance of

growth of, 9.1, 9.2, 11.1, 14.1, 17.1

iconic types of

measuring expansion of

transplantation from wild patches

Mycena chlorophos

Mycofiltration, 2.1, 5.1

Mycophobia

Mycorrhizal mushrooms, 2.1, 2.2, 4.1, 5.1

Mycosphere

definition of

synergistic

MYPA

N

Naematoloma (genus), 21.1, 21.2

Naematoloma capnoides

Naematoloma fasciculare

Nameko. See Pholiota nameko

Namerako. See Pholiota nameko

Nametake. See Flammulina velutipes

Natural culture

advantages and disadvantages

inoculating with pure cultured spawn

log culture, 4.1, 6.1, 21.1

methods of

polyculture environment

site location

species sequencing

spore-mass inoculation

stumps

timing inoculation

transplantation

Nematodes, 2.1, 14.1, 21.1

Nesterov, Vladimir

Newsletters

Noble Polypore. See Bridgeoporus nobilissimus

Nutrient deprivation

Nutrient limitation

Nutrition, . See also individual species

O

Oakwood Mushroom. See Lentinula edodes

Oatmeal Agar (OMA)

Oatmeal, Malt, Yeast Enriched Agar (OMYA)

“Oetzi.” See “Iceman”

Oidia

Okara

Old Man’s Beard. See Hericium erinaceus

Oligoporus (genus)

OMA

Omelet

Omon’s Oyster Mushroom. See Pleurotus tuberregium

OMYA

Orange Peel Mushroom. See Aleuria aurantia

Oregon White Truffle. See Tuber gibbosum

Organic certification

Ott, Jonathan

Outdoor cultivation. See Natural culture

O’warai-take. See Gymnopilus spectabilis

Ower, Ron, 21.1, 21.2

Oxyporus nobilissimus, 2.1, 21.1

Oyster mushrooms. See Pleurotus

Oyster Shelf. See Pleurotus ostreatus

P

Packaging, 23.1, 23.2

Paddy Straw Mushroom. See Volvariella volvacea

Panacea Polypore. See Ganoderma lucidum

Panaeolus cyanescens

Panaeolus subbalteatus, 2.1, 3.1

Panaeolus tropicalis

Paper products

Parasitic mushrooms

Parasol Mushroom. See Lepiota procera

Pasania. See Lentinula edodes

Pasteur, Louis

Pasteurization

Pâté

PCBs, 2.1, 2.2

PCPs

PDA, 12.1, 12.2

PDYA

PDYPA

Peck’s Morel. See Morchella angusticeps

Perigold Black Truffle. See Tuber melanosporum

Permaculture

Peziza badio-confusa

Peziza phyllogena

Phanerochaete chrysosporium

Phase II chamber

Phellinus linteus

Phenotypes

Phoenix Mushroom. See Pleurotus pulmonarius

Pholiota (genus), 4.1, 21.1, 21.2

Pholiota aegerita

Pholiota cylindracea

Pholiota glutinosa

Pholiota limonella, 15.1, 21.1

Pholiota nameko (Nameko), 21.1

agar culture media

available strains

casing

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 17.1, 21.1

growth parameters

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 14.1, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 4.2, 21.1

natural habitat

nutritional content

in permaculture

primordia formation

spawn media

species sequencing

spore-mass inoculation

taxonomy

yield potentials

Pholiota squarrosa-adiposa

Pholiota terrestris

Pholiotina filaris

Phorid flies

Photosensitivity

Pink Oyster Mushroom. See Pleurotus djamor

Pioppino. See Agrocybe aegerita

Piptoporus betulinus, 1.1, 21.1, 21.2

Pisolithus tinctorius

Plato

Pleurocystidia, 9.1, 9.2

Pleurotus (genus, Oyster mushrooms), 21.1. See also individual species

advantages of cultivating

bag culture

biological efficiency

by-products

colors

column culture

disadvantages of cultivating

drying

flies and

fruiting substrates, 6.1, 6.2, 6.3, 6.4, 14.1, 17.1, 18.1

harvesting

Hypsizygus and Lyophyllum vs., 21.1

log culture, 4.1, 4.2

market share

mycelial characteristics, 13.1, 13.2

nutrition

in permaculture

photosensitivity, 14.1, 21.1, 21.2

as primary decomposers

primordia formation

recipes, 24.1, 24.2, 24.3, 24.4

secondary metabolites

species sequencing

spoiling

taxonomy

timing of crops

toxic waste and, 2.1, 2.2

tray culture

Pleurotus abalonus, 13.1, 13.2, 21.1

Pleurotus citrinopileatus (Golden Oyster), 21.1

agar culture media

available strains

comments, 21.1, 21.2

common names

description

distribution

flavor and cooking, 14.1, 21.1

fragrance signature

fruiting containers, 19.1, 21.1

fruiting substrates, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

primordia formation

spawn media

spore-mass inoculation

taxonomy

temperature requirements

yield potentials

Pleurotus columbinus

Pleurotus cornucopiae, 3.1, 21.1

Pleurotus corticatus

Pleurotus cystidiosus (Abalone), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 9.1, 13.1, 13.2, 13.3, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

spore-mass inoculation

taxonomy

yield potentials

Pleurotus djamor (Pink Oyster), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 21.1

fruiting substrates, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

primordia formation, 13.1, 13.2

spawn media

spore-mass inoculation

taxonomy

yield potentials

Pleurotus dryinus, 3.1, 21.1

Pleurotus elongatipes

Pleurotus eous, 21.1, 21.2

Pleurotus eryngii (King Oyster), 21.1

agar culture media

available strains

casing, 19.1, 20.1

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 4.1, 17.1, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

species sequencing

spore-mass inoculation

taxonomy

yield potentials

Pleurotus euosmus (Tarragon Oyster), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

primordia formation

spawn media

spore-mass inoculation

taxonomy

yield potentials

Pleurotus flabellatus, 21.1, 21.2, 21.3

Pleurotus florida

Pleurotus floridanus

Pleurotus fuscus

Pleurotus ostreato-roseus

Pleurotus ostreatus (Tree Oyster), 21.1

agar culture media

available strains

by-products

comments

common names

as cultivation candidate

description

distribution

on dying trees

flavor and cooking

fragrance signature

fruiting containers, 19.1, 19.2, 19.3, 21.1

fruiting substrates, 4.1, 18.1, 18.2, 21.1

growth parameters

harvesting, 14.1, 21.1, 23.1

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 13.1, 13.2, 13.3, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nematodes

nutritional content

in permaculture

primordia formation

Shiitake vs.

spawn media

species sequencing, 22.1, 22.2

speed of colonization

spore-mass inoculation

on stumps

taxonomy, 21.1, 21.2, 21.3

yield potentials

Pleurotus populinus, 21.1, 21.2

Pleurotus pulmonarius (Phoenix or Indian Oyster), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers, 19.1, 19.2, 19.3, 21.1

fruiting substrates, 6.1, 18.1, 21.1

growth parameters

growth subsequent to harvest

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

in permaculture, 5.1, 5.2

primordia formation

spawn media

speed of colonization

spoiling

spore-mass inoculation

taxonomy, 21.1, 21.2, 25.1

temperature requirements

yield potentials

Pleurotus sajor-caju. See also Pleurotus pulmonarius

misapplied, 21.1, 21.2, 21.3, 21.4, 25.1

true

Pleurotus salmoneo-stramineus, 21.1, 21.2

Pleurotus sapidus

Pleurotus smithii, 13.1, 13.2, 21.1

Pleurotus tuberregium (King Tuber Oyster), 21.1

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 17.1, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

sclerotia, 9.1, 21.1

spawn media

taxonomy

yield potentials

Pleurotus ulmarius

Pluteus (genus)

Pluteus cervinus/P. atrocapillus (Deer), 3.1, 4.1

Poisonings, 1.1, 1.2, 23.1

Pollock, Steven

Polypore mushrooms, . See also individual species

as cultivation candidates

health benefits of

in permaculture

Polyporus betulinus

Polyporus frondosus

Polyporus indigenus

Polyporus saporema

Polyporus sulphureus. See Laetiporus sulphureus

Polyporus tuberaster, 21.1, 21.2

Polyporus umbellatus (Zhu Ling), 21.1

agar culture media

available strains

casing, 14.1, 20.1

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates

growth parameters

introduction

marketed products

medicinal properties, 21.1, 21.2

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

sclerotia, 9.1, 13.1, 21.1

spawn media

taxonomy, 21.1, 21.2

yield potentials

Polyporus versicolor

Polysaccharides

Pom Pom. See Hericium erinaceus

Poria cocos

Portobella/portobello/ports. See Agaricus brunnescens

Potato Dextrose Agar (PDA), 12.1, 12.2

Potato, Dextrose, Yeast Agar (PDYA)

Potent Psilocybe. See Psilocybe cyanescens

Preconditioning plenum

Pricing

Primary decomposers

Primordia formation, 9.1, 13.1, 14.1, 21.1

Prince. See Agaricus augustus

Psathyrella (genus)

Pseudomonas putida

Psilocin

Psilocybe (genus), 1.1, 4.1, 5.1, 21.1, 21.2

Psilocybe australiana

Psilocybe azurescens, 4.1, 21.1, 21.2, 21.3, 21.4

Psilocybe bohemica

Psilocybe cubensis

bottle culture

cap orientation

casing

as cultivation candidate

mycelial characteristics

photosensitivity

Psilocybe cyanescens (Caramel Capped Psilocybes), 21.1

agar culture media

available strains

comments

common names

as cultivation candidate

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 6.1, 21.1

growth parameters

introduction

medicinal properties

microscopic features

mycelial characteristics, 13.1, 21.1

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

taxonomy

in wood chips

yield potentials

Psilocybe cyanofibrillosa, 21.1, 21.2

Psilocybe mexicana (Teonancactl), 9.1, 13.1, 21.1

Psilocybe serbica, 21.1, 21.2

Psilocybe subaeruginosa, 21.1, 21.2

Psilocybe tampanensis

Psilocybin

PSK

PSP

Pulp waste

Pycnoporus cinnabarinus

Q

Quiches, 24.1, 24.2

R

Recipes, . See also Cookbooks

Broiled Rockfish in an Oyster or Shimeji Mushroom and Ginger Sauce

Cheese-Mushroom Quiche

Chicken with Oyster Mushrooms

Dragon’s Mist Soup

Fresh Shiitake Omelet

Hot Mushroom Dip Especial

Killer Shiitake

Maitake “Zen” Tempura

Mediterranean Mushroom

Morel Crème Superieur

Morel Quiche

Oyster Mushrooms with Basmati Rice and Wild Nettles

Pickled Maitake (Hen-of-the-Woods)

Shiitake Hazelnut Vegetarian Pâté

Shiitake in Burgundy Butter Sauce

Shiitake or Maitake Clear Soup

Shiitake Teriyaki

Stuffed Portobello Mushroom

Red Woodlover. See Hypholoma sublateritium

Reishi. See Ganoderma lucidum

Religious ceremonies

Replicate fading

Retorts

Reyers, Zeger

Rhizinia undulata

Rhizomorphs, 9.1, 13.1

Rhodotorula glutinis

Rigidioporus ulmarius

Roberts, Jim

Roger, Maggie

Rosellini, Robert

Royal Sun Agaricus. See Agaricus blazei

Rozites caperata

Ruck, Carl

Ruffles. See Sparassis crispa

S

Sacred Medicinal Mushroom Forests and Gardens

Sacred Psilocybe Mushroom Patches

Saiwai-take. See Ganoderma lucidum

Salmon Oyster Mushroom. See Pleurotus djamor

Salzman, Emanuel

Saprophytic mushrooms, 2.1, 2.2. See also individual species

Sarunouchitake. See Ganoderma lucidum

Satyr’s Beard. See Hericium erinaceus

Sawdust, enriched

achieving full colonization

creating production blocks

cultivation problems and solutions

handling bags post–full colonization

incubating production blocks

inoculating

Lentinula edodes on, 21.1

sterilizing

testing for moisture content

Sawdust spawn

creating

in outdoor substrates

overview of technique

uses for

Scaly Lepiota. See Lepiota rachodes

Sciarid flies

Sclerotia, 9.1, 13.1, 13.2, 21.1, 21.2

Secondary decomposers

Seed hulls

Seminars

Septae

Serres, Olivier de

Sexual virility, stimulation of

Shaggy Mane. See Coprinus comatus

Sheep’s Head. See Hericium erinaceus

Shiang Ku. See Lentinula edodes

Shiangu-gu. See Lentinula edodes

Shiitake. See Lentinula edodes

Shimeji Mushroom, 21.1, 21.2, 24.1, 24.2

Shirokikurage. See Tremella fuciformis

Shirotamogitake. See Hypsizygus ulmarius

Silver Ear Mushroom. See Tremella fuciformis

Singer, Rolf, 21.1, 21.2, 21.3

Slanted wall culture

Slime Pholiota. See Pholiota nameko

Smith, Alexander, 21.1, 21.2

Smokey Gilled Hypholoma. See Hypholoma capnoides

Smooth Lepiota. See Lepiota naucina

Snow Mushroom. See Tremella fuciformis

Societies. See Associations and societies

Soma

Songrong. See Agaricus blazei

Sophocles

Soups, 24.1, 24.2

South Poplar Mushroom. See Agrocybe aegerita

Soybean roughage

Sparassis crispa (Cauliflower), 21.1, 21.2

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

in permaculture

spawn media

taxonomy

yield potentials

Sparassis herbstii, 21.1, 21.2, 21.3

Sparassis laminosa, 21.1, 21.2

Sparassis radicata, 21.1, 21.2, 21.3

Sparassis spathulata, 21.1, 21.2

Spawn. See also Grain spawn; Sawdust spawn

definition of

disk method

homemade vs. commercial

inoculating outdoor substrates with

matching to substrate

pelletized (granular)

run

sources for

storing, 8.1, 15.1

Species diversity

loss of

permaculture and

Species sequencing, 4.1, 5.1, 21.1, 22.1

Spores

collecting, 4.1, 12.1

formation of, 9.1, 9.2

germinating

load factors

-mass inoculation, 4.1, 15.1, 15.2

-mass slurry

number produced

prints, 4.1, 12.1, 12.2

release of, 9.1, 9.2

role of, 9.1, 9.2

SPV

Stamets, Azureus, 21.1, 21.2

Stamets, LaDena, 5.1, 21.1, 21.2, 21.3

Stamets, Lillian

Stamets “P” Value (SPV)

Steam pasteurization

Steinernema feltia

Sterigmal appendage

Sterigmata

Sterilization, 10.1, 17.1

Stickney, Larry

Storing, 14.1, 23.1, 23.2, 25.1

Strains. See also Cultures

banks

evaluating

importance of

starting, by cloning

storing

Straw culture, 6.1, 18.1, 25.1. See also Agricultural waste products

Straw Mushroom. See Pleurotus ostreatus; Volvariella volvacea

Strawberry Oyster Mushroom. See Pleurotus djamor

Stropharia (genus)

Stropharia ambigua

Stropharia ferrii

Stropharia imaiana

Stropharia rugosoannulata (King Stropharia), 21.1

agar culture media

available strains

casing, 14.1, 20.1, 20.2

comments

common names

as cultivation candidate

degeneration

description

distribution

flavor and cooking, 14.1, 21.1

fragrance signature, 13.1, 21.1

fruiting containers

fruiting substrates, 4.1, 6.1, 6.2, 14.1, 18.1, 21.1

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics, 4.1, 13.1, 13.2, 13.3, 21.1

mycelial mass expansion

natural cultivation method, 4.1, 21.1

natural habitat

nutritional content

in permaculture

as primary decomposer

recipe

secondary metabolites

spawn media

species sequencing, 4.1, 22.1, 22.2

taxonomy

yield potentials

Strophariaceae, 21.1, 21.2

Study tours

Stumps

Submerged pasteurization, 18.1, 18.2

Substrates. See Fruiting substrates

Sugarcane bagasse

Sumerlin, David

Super-pasteurization

Swordbelt Agrocybe. See Agrocybe aegerita

Szechwan Restaurant Syndrome

T

Tabang Ngungut. See Pleurotus djamor

Takiiro Hiratake. See Pleurotus djamor

Tamogitake. See Pleurotus citrinopileatus; Pleurotus ostreatus

Tamo-motashi. See Hypsizygus tessulatus

Tarragon Oyster Mushroom. See Pleurotus euosmus

Taxol

Taxomyces andreanae

Temperature

conversion tables

fruitbody development and, 14.1, 21.1

primordia formation and, 21.1, 21.2

recording

spawn run and

Tempura

Teonancactl. See Psilocybe mexicana

Termite mushrooms

Termitomyces (genus)

Termitomyces robustus

Terracina, Salvatore

Tertiary decomposers

Test tube slants

Thaithatgoon

Thermogenesis

Tiger Milk Mushroom. See Pleurotus tuberregium

Toxic wastes

Training centers

Trama

Trametes cinnabarinum

Trametes versicolor (Turkey Tail), 21.1

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties, 21.1, 21.2

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

in permaculture

spawn media

taxonomy

yield potentials

Transplantation

Tray culture

Tree Ear. See Auricularia polytricha

Tree Oyster Mushroom. See Pleurotus ostreatus

Tree species

Tremella (genus)

Tremella aurantia, 21.1

Tremella fuciformis (White Jelly), 21.1

agar culture media

available strains

comments

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates

growth parameters

harvesting

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

taxonomy

yield potentials

Tremella mesenterica, 21.1, 21.2

Trichoderma

Tricholoma giganteum

Tricholoma magnivelare (Matsutake), 2.1, 2.2, 2.3

Troubleshooting guide

agar culture

grain culture

harvest stage

post-harvest

pre-harvest period

straw culture

supplemented sawdust culture

Truffles, 1.1, 2.1

Tsuchi-maitake. See Polyporus umbellatus

Tuber gibbosum (Oregon White Truffle), 2.1

Tuber melanosporum (Perigold Black Truffle), 2.1

Tumors. See Cancer

Turkey Tail. See Trametes versicolor

U

ULPA filters

Umbrella Polypore. See Polyporus umbellatus

UV lights

V

Vedic literature

Velvet Foot Collybia. See Flammulina velutipes

Verpa bohemica (Early Morel), 21.1

Vertical wall culture

Viscid Mushroom. See Pholiota nameko

Volk, Thomas

Volvariella bakeri

Volvariella volvacea (Paddy Straw), 21.1

agar culture media

available strains

casing

comments, 21.1, 21.2

common names

description

distribution

flavor and cooking

fragrance signature

fruiting containers

fruiting substrates, 18.1, 21.1

growth parameters

harvesting, 21.1, 23.1

introduction

marketed products

medicinal properties

microscopic features

mycelial characteristics

mycelial mass expansion

natural cultivation method

natural habitat

nutritional content

spawn media

species sequencing

speed of colonization

storing strains

taxonomy

temperature requirements, 14.1, 15.1

yield potentials

Vomited Scrambled Egg Fungus. See Fuligo cristata

W

Warm-Weather Button Mushroom. See Agaricus bitorquis

Wasson, R. Gordon, 1.1, 21.1, 21.2

Water crystals, 20.1, 20.2

Web sites

Weil, Andrew, 21.1, 21.2, 21.3, 21.4, 24.1

White Elm Mushroom. See Hypsizygus ulmarius

White Jelly Fungus. See Tremella fuciformis

White Jelly Leaf. See Tremella fuciformis

White Morel. See Morchella esculenta

White rot fungi

Wine Cap. See Stropharia rugosoannulata

Wine Red Stropharia. See Stropharia rugosoannulata

Winter Mushroom. See Flammulina velutipes

Witch’s Butter. See Tremella mesenterica

Wolfiporia cocos

Wood. See also Log culture; Sawdust, enriched; Sawdust spawn; Stumps

chips, 4.1, 6.1, 6.2

types

Wood Blewit. See Lepista nuda

Wood Ears, 3.1, 21.1. See also Auricularia polytricha

Wu Sang Kwuang

Y

Yamabiko Hon-shimeji. See Hypsizygus tessulatus

Yamabushi-take. See Hericium erinaceus

Yanagi-matsutake. See Agrocybe aegerita

Yao, Dusty

Yeast fermentation method

Yellow Morel. See Morchella esculenta

Yield. See also individual species

biological efficiency

optimizing, 7.1, 21.1

Yin Er. See Tremella fuciformis

Yu-er. See Auricularia polytricha

Yuki-motase. See Flammulina velutipes

Yun Zhi. See Trametes versicolor

Yung Ngo. See Auricularia polytricha

Z

Zhu Ling. See Polyporus umbellatus

Zhuzhuang-Tiantougu. See Agrocybe aegerita