All about Mushrooms

Wed, 07 Oct 2009 09:09:59 +0100

Introduction

Small-scale mushroom production represents an opportunity for farmers interested in an additional enterprise and is a specialty option for farmers without much land. This publication is designed for market gardeners who want to incorporate mushrooms into their systems and for those farmers who want to use mushroom cultivation as a way to extract value from woodlot thinnings and other "waste" materials. Mushroom production can play an important role in managing farm organic wastes when agricultural and food processing by-productsare used as growing media for edible fungi. The spent substrate can then be composted and applied directly back to the soil. This publication includes resources for entrepreneurs who wish to do further research.

Many people are intrigued by mushrooms’ nutritional and medicinal properties, in addition to their culinary appeal. Mushrooms contain many essential amino acids; white button mushrooms, for example, contain more protein than kidney beans. Shiitake mushrooms are less nutritious, but are still a good source of protein.(Royse and Schisler, 1980) As a group, mushrooms also contain some unsaturated fatty acids, provide several of the B vitamins, and vitamin D. Some even contain significant vitamin C, as well as the minerals potassium, phosphorus, calcium, and magnesium.(Park, 2001)

Asian traditions maintain that some specialty mushrooms provide health benefits. Chinese doctors use at least 50 species. Two recent books, Medicinal Mushrooms: An Exploration of Tradition, Healing and Culture and Medicinal Mushrooms You Can Grow, detail existing research on the health benefits of mushrooms. See the Resources section at the end of this guide for specifics on these books and other sources of information.

Mushroom production is labor- and management-intensive. Specialty mushrooms are not a "get rich quick" enterprise. On the contrary, it takes a considerable amount of knowledge, research, planning, and capital investment to set up a production system. You must also be prepared to face sporadic fruiting, invasions of "weed" fungi, insect pests, and unreliable market prices.

Growing Mushrooms

Mushroom production is completely different from growing green plants. Mushrooms do not contain chlorophyll and therefore depend on other plant material (the "substrate") for their food. The part of the organism that we see and call a mushroom is really just the fruiting body. Unseen is the mycelium—tiny threads that grow throughout the substrate and collect nutrients by breaking down the organic material. This is the main body of the mushroom. Generally, each mushroom species prefers a particular growing medium, although some species can grow on a wide range of materials.

If you are considering mushroom production, become thoroughly familiar with the life cycles of fungi. A very general description is included below. A plant pathology textbook is a good resource for learning more about these complex life cycles.

Once you are familiar with the various fungi life cycles, learn the growth requirements of each of the species you are considering. Two basic references are The Mushroom Cultivator, by Stamets and Chilton, and the aforementioned Growing Gourmet and Medicinal Mushrooms, by Stamets (see Resources).

Growing mushrooms outdoors as a part of a market garden involves little effort after you have inoculated the logs or other substrate with the mushroom spawn. Your duties are mainly to maintain humidity and monitor for fruiting. When mushrooms appear, you add them to your other garden products and sell them. (See Mushrooms on the Farm and in the Garden, below.)

Most available markets, however, require more mushrooms than occasional fruiting provides. Indoor production can fill the gaps when outside fruiting lags. The entire operation can also be conducted inside. However, indoor mushroom production demands a much higher level of knowledge, continuous monitoring, and timely manipulation of environmental conditions.

Producing nutritious food at a profit, while using materials that would otherwise be considered "waste," constitutes a valuable service in the self-sustaining community we might envision for the future.

These are the steps in mushroom production— a cycle that takes about 15 weeks (time varies by species) from start to finish.

Choosing a growing medium

Pasteurizing or sterilizing the medium

Seeding the beds with spawn (material from mature mushrooms grown on sterile media)

Maintaining optimal temperature, moisture, and other conditions for mycelium growth and the conditions that favor fruiting (This is the most challenging step.)

Harvesting, packaging, and selling the mushrooms

Cleaning the facility and beginning again

The substrate on which the mushrooms will fruit must be sterilized or pasteurized in order to destroy any fungal and/or bacterial competitors. Low-tech substrate preparation methods are described in the books by Paul Stamets and by Peter Oei (see Resources).

To produce spawn, you inoculate a pasteurized medium, usually grain, with the sterile culture of a particular mushroom species. After the culture has grown throughout the medium, it is called spawn. Producing spawn requires exacting laboratory procedures. Terri Marie Beauséjour,cultivation chair for the Mycological Society of San Francisco, has written an excellent article that can help the beginner who is put off by the technical aspects of mushroom cultivation. Titled "Getting Started with Mushroom Cultivation: The Wisdom of Simplicity," it is available on the Web at <www.mykoweb.com/articles/cultivation.html>.

Many mushroom suppliers sell several kinds of spawn, and the beginning mushroom farmer should take advantage of this selection in early trials to determine which species grow best on available materials. Eventually, learning to produce spawn might reduce your cost of production. Evaluate this possibility only after you have mastered the later stages of cultivation.

While the mycelium is growing—and until it fully occupies the substrate—the mushroom farmer typically manipulates the growing environment to favor mycelial growth. The atmospheric conditions are then changed to initiate "pinheads," and then to complete fruiting. For example, in oyster mushroom production under closely controlled conditions, the grower lowers the temperature and the CO_{2 in the grow room to initiate fruiting. Each species has specific requirements for its stages of development.}

rmaculture is a system of combining perennials, trees, shrubs, and vines to create a "permanent agriculture." Using an intensive design process, the natural elements of an ecosystem are replaced by food-producing relatives, creating an edible landscape.

Paul Stamets was an early advocate of integrating a variety of mushrooms into a permaculture system.(Stamets, 1994) In his design, agricultural wastes like cornstalks, wheat straw, or rice straw can be used as growing media for oyster mushrooms. After harvest, the spent substrate can be recycled as fodder or mulch for garden soils.

Shaggy manes (Coprinus comatus), Stamets notes, do well on manured soils and near compost piles. The King stropharia or wine cap mushroom (Stropharia rugoso-annulata) grows best outdoors and plays a key role as a recycler of woody debris. Bees, attracted to the sweet mycelium, help pollinate the green garden plants. The mushrooms are good to eat when small. Large, mature mushrooms attract fly larvae that make excellent fish or poultry food. These can supplement feed for other on-farm enterprises or be sold to pet stores.

Stamets also uses King stropharia mushrooms for their ecological benefits. He found that, when established along waterways, they acted as microfilters of fecal coliform bacteria generated by his small herd of cattle. He also planted them along greywater runoff areas. Stamets believes mushrooms can play a large role in mycofiltration.(Stamets, 2000-2001)

Stamets grows shiitakes, namekos (Pholiota nameko), and Lion’s mane (Hericium erinaceus) mushrooms on inoculated logs set in a fence row, while other species like maitake (Grifola frondosa), reishi (Ganoderma lucidum), and clustered wood-lovers are cultivated on stumps as part of a hardwood forest management system. He introduces mycorrhizal species such as chanterelles, King boletes, and others to new areas by "satellite planting," in which seedlings are planted near trees that have a desired mushroom species growing around them. After several years, the seedlings and their mycorhizal associates are transplanted, creating new patches of mushrooms. Morels are more difficult to propagate, but some types can be encouraged through the use of small burns.information on the requirements for 16 species.(Stamets & Chilton, 1983)

When you can cut the time between harvests, annual production increases. Short cycles are what large-scale commercial producers aim for, constantly looking for ways to increase efficiency. This is the competition you face if you plan to sell your product on the wholesale market.

Paul Stamets of Fungi Perfecti, an educational and mushroom supply company (See Resources), has spent most of his life studying the growth and cultivation of fungi. His book Growing Gourmet & Medicinal Mushrooms (see Resources) is an invaluable resource for anyone considering the cultivation of any mushroom species. He describes several alternative methods of producing mushrooms, including growing them outdoors on logs, on stumps, and in the garden, as well as indoors in bags or on columns.

Peter Oei, in his Manual on Mushroom Cultivation (see Resources), describes in some detail how alternative mushroom production systems have been used successfully in developing countries. Many ideas for low-input systems are included. In practice, it is unlikely that the beginner can successfully compete in the wholesale market against highly capitalized and efficient mushroom companies. A better choice for the beginner is to develop a niche market for high-quality fresh mushrooms, then sell them at retail, or to produce a value-added mushroom product, such as a soup mix or sauce.

Mushrooms on the Farm and in the Garden

Fungi cycle nutrients that nourish new life in the soil. Recognizing this essential function, inventive gardeners integrate mushrooms into farm, garden, and permaculture systems. Mushrooms can also be grown in lawns, polytunnels, vegetable gardens, and woodlands.(Edwards, 2000)

Terri Marie Beauséjour, a writer for Mushroom the Journal, encourages creativity and imagination when planting mushrooms in a garden. Look at the "fungamentals," she writes, the necessities such as available substrates, microhabitats, sun, shade, wind, and humidity conditions. Gardens offer ample substrates—organic waste materials—while plants provide shade and humidity. Plug-inoculated blocks buried among plantings work well for oyster and Stropharia rugoso-annulata mushrooms. Beauséjour suggests using a misting sprinkler for mushrooms in gardens. (Beauséjour, 1999)

Grower and author Ken Litchfield notes that mulching, a standard gardening practice, not only regulates soil temperature and humidity but also nourishes fungi. He also suggests surrounding raised beds with partially buried logs to create mushroom habitats. Inside the beds, vegetables, flowers, and shrubs offer the requisite shade and humidity for mushroom cultivation. In weedy areas, Litchfield suggests putting down organic material and covering it with wet cardboard and wood chips, an ideal substrate for fungi.(Litchfield, 2002)

These methods of production are not likely to yield huge numbers of mushrooms. However, they can provide an attractive addition to directly marketed produce.

Choosing a Mushroom Species

A mushroom cultivation kit (check with suppliers listed below) is a handy way to begin to understand the fungal life cycle. Once you successfully use the kit, you can begin to learn the steps that precede that final fruiting stage of the mushroom life cycle. Purchase spawn that will grow on materials you have available. Then design and test a system that duplicates the conditions favorable to all stages of growth. You can use this experience to learn how to create sterile cultures and spawn for the species you are growing.

Choose the species to grow by thinking about:

What waste materials are readily available to use as a growth medium?

What kind of facility or environment is available? • •

How much will the necessary equipment cost?

What level of skill is required to manage the life cycle of the fungus?

What is market demand for this species?

According to these criteria, oyster (Pleurotus species) and shiitake (Lentinus edodes) mushrooms are probably best for most novices, although the maitake (Grifola frondosa) is also a possibility. The former two are relatively easy to grow, and there is already a market for them, largely because commercial producers of white button (Agaricus bisporus) mushrooms have been diversifying into specialty mushrooms. If you intend to grow mushrooms commercially, shiitake or oyster mushrooms are your best choices. These two species are more thoroughly covered in the following sections.

A chart in the Appendix lists other common species and the materials on which they can be cultivated. Test each species you are considering against each of the questions listed above.

Species for Beginners

Oyster mushrooms

Oyster mushrooms (Pleurotus species) are a good choice for beginning mushroom cultivators because they are easier to grow than many of the other species, and they can be grown on a small scale with a moderate initial investment. Although commonly grown on sterile straw from wheat or rice, they will also grow on a wide variety of high-cellulose waste materials. Some of these materials do not require sterilization, only pasteurization, which is less expensive. Another advantage of growing oyster mushrooms is that a high percentage of the substrate converts to fruiting bodies, increasing the potential profitability. • • •

Oyster mushrooms can become an integral part of a sustainable agriculture system. Many types of organic wastes from crop production or the food processing industry can be used to support oyster mushroom production.

Although there are no books devoted entirely to oyster mushroom production, Stamets’ books provide basic information. Research on using various agricultural and forest wastes as substrates is reported in the recently published Mushroom Biology and Mushroom Products, edited by D.J. Royse.(Royse, 1996) Peter Oei (Oei, 1991) documents a number of commercial production systems for some strains grown in developing countries.

There is an increasing number of Web sites devoted to oyster mushroom production. Lawrence Weingarten describes his production process on his Web site, complete with photos at <www.mycowest.org/cult/i-grow/i-grow-1.htm>.

Two Canadian Web sites also offer additional advice:

Oyster Mushroom Cultivation www.gov.ns.ca/nsaf/elibrary/archive/hort/vegetables/pihve94-03.htm • The MushWorld Web site, <www.mushworld.com/home>, contains excellent technical information about growing oyster mushrooms. The site requires registration, but it is free.

Oyster mushroom cultivation has one significant drawback: some people are allergic to the spores. In these cases, air-cleaning equipment or respirators are necessary in order to safely work in the production facility.

The consumer market for oyster mushrooms is being developed by the larger mushroom companies as they diversify their operations. However, because of the short shelf life of many oyster mushroom varieties, this species may offer a special advantage to the local grower who markets directly and can consistently deliver a fresh, high-quality product.

Shiitake mushrooms

Shiitakes (Lentinus edodes) are well suited as a low-input alternative enterprise because they, like oyster mushrooms, can be grown on a small scale with a moderate initial investment. Shiitake cultivation has been thoroughly investigated, and a commercial market already exists in most areas of the United States. Shiitake mushrooms are • grown on logs, either inside or outside. Inside, they can also be grown on compressed sawdust logs or in bottles or bags. See the brief description of these production systems below. Several excellent books and Web sites are also listed below in Resources (shiitake).

Log Production

Hardwood logs approximately 4" to 6" in diameter and of an easily handled length (commonly four feet) are cut during a tree’s dormant season. Oaks, sweetgum, cottonwood, beech, birch, willow, and other non-aromatic hardwoods are appropriate species. The denser woods produce for up to twice as long as the softer ones. Smaller diameter logs produce more quickly than larger ones, but for a shorter time.

Handle the logs carefully to avoid soil contact and damage to the bark. This will help prevent contamination by competing fungi. Inoculate the logs with spawn from a strain suitable to your production system. There is a wide variety of spawn from which to choose and several inoculation methods.

After inoculation, the spawn develops a thread-like network—the mycelium—growing throughout the log. During this time, you must protect the logs from dehydration by the sun and wind. Spray or mist the logs to maintain the humidity necessary to keep the mycelium alive and growing. When the mycelium has fully occupied the logs and the temperature and humidity are right for fruiting, the mycelium will initiate tiny "pinheads" at the surface of the log. The pinheads grow into mushrooms in the next couple of days.

To stimulate fruiting, some growers soak the logs in water tanks and/or "shock" them by physical impact or chilling. Others leave the logs in the growing environment and harvest when they naturally fruit.

Be alert for signs that fruiting is beginning. The best grades of shiitakes have caps that still have a slight curl at the edge. Harvest often if you want to earn the best price for your mushrooms. In addition, if you want to deliver a premium product, you must pay attention to post-harvest storage, packaging, and shipping.

Golden Oyster Mushrooms • Glen Babcock – Garden City Fungi

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Many shiitakes are raised organically. Although it is easier to produce shiitakes organically than some of the other mushrooms, "weed" fungi, as well as pests such as slugs and flies, can reduce fruiting and quality. The producer must monitor, quickly identify, and control these pests or lose some of the crop.

Federal law now controls the use of the word "organic" in marketing. In order to label a product organic, producers must be certified by an accredited third party and document their production and handling practices. For further information, call and request the ATTRA publication Organic Farm Certification & the National Organic Program, or see it at our Web site, <www.attra.ncat.org>.

Growing Shiitakes on Sawdust

Today, most shiitakes and many other mushroom species are raised on a sterilized sawdust substrate. Although this method allows a much faster fruiting cycle and a high level of return (110% or more of initial dry weight), it also demands a greater capital investment and more skillful management than log production. In order to achieve fruiting as quickly as possible, you need a building in which you can control the temperature and moisture. The building must be easy to keep clean, and sanitary procedures must be strictly followed to avoid contamination.

The chamber and the steam processor to pasteurize or sterilize the sawdust can represent a significant initial investment. For example, Crop King sells a small mushroom production system, including an inoculation table and bagging station, for about $5,000. The company’s complete growing system—including equipment, structural components, and technical support—can come to more than $41,000. Recovering these costs is a challenge for a beginner—especially at current mushroom prices.

However, innovative producers have used concrete mixers to blend supplemental ingredients and made pasteurized substrate in barrels. Fungi Perfecti sells pressure sterilizers for $200 to $1,000, but warns that they are not designed for commercial production.

Using hydrogen peroxide instead of conventional pasteurization is a relatively recent innovation. A manual on this method and more information is available at <www.mycomasters.com/>.

Growing mushrooms on sawdust requires attention to detail—especially careful monitoring and timely processing of the blocks, bottles, or bags. Several of the books listed below, including Stamets (1993) and Przybylowicz and Donoghue (1990), offer more details about this production method.

Shiitake Prices

The price for shiitake mushrooms fluctuates throughout the season. Prices are highest in the winter when supply is low, and lowest in summer when production peaks. Except in very mild climates, the only logs that fruit in winter are those maintained indoors. Using strains selected to fruit at cooler temperatures can lengthenarvest season and allow producers to capture the higher prices. See the marketing section below for ways to counteract the natural price cycle.

Sources of Further Information on Shiitakes

Several states, including Pennsylvania, California, and Oregon, support university research on shiitakes and may have Extension specialists who can provide information to growers in their states. Others have Extension publications with information specific to their areas. Some of these resources are available on-line at Web sites listed in the Resources section. An excellent example is the site maintained by the Ohio State University.

In states without this Extension support, one of the best ways to learn about production is to share information with other growers. There are several local grower organizations, many of which publish newsletters. Ask your state Extension horticultural specialist about local organizations, or you can contact the North American Mycological Association or the American Mushroom Institute (see Resources). There are also several books specifically about shiitake production. See Resources (shiitake) for more information.

Other Mushroom Species

Mushroom Species with Limited Commercial Production

Some species of mushrooms are not yet commercially cultivated. Many of these are mycorrhizal types; that is, they grow only in conjunction with the roots of a higher plant. Matsutakes and chanterelles are typical examples of such mushrooms.

Mycorrhizal mushrooms are the hardest to grow commercially, because the needs of both the fungus and the host plant must be met in order to produce a commercial crop. Also, the host plant typically must reach a certain physiological maturity before the fungus will fruit. When the host is a tree, this maturation may be measured in decades. Nevertheless, highly prized morels and truffles are mycorrhizal, and they are both now being grown commercially in the United States.

Morels

Commercial production of morels on anything but a small-scale, seasonal basis is currently not a practical option. Morels are being grown year-round, using a patented process, at only one production facility in North America (in Alabama). The patent and facility are owned by Terry Farms and represent the only successful commercial process for fruiting these highly valued mushrooms out of season.

It is, however, possible to establish a morel patch by using a morel starter kit. If you are successful, these mushrooms will fruit in the spring at the same time as wild morels. Morel prices are, understandably, at their lowest during this natural fruiting season. Adding them to a farmers’ market stand would certainly attract morel-loving customers. You can also dry the product for year-round sales if you can grow commercial quantities in your patch.

Tom Volk’s Web site, <http://botit.botany.wisc.edu/toms_fungi/morel.html>, has particularly good information about morel mushroom production.

Truffles

Growers generally begin truffle production by

Morel Mushrooms

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dipping tree seedlings in a mycorrhizal slurry before planting. After several years, under favorable growing conditions for both the tree and the fungus, truffles form underground fruiting bodies that roughly resemble potatoes. These range from the size of a pea to that of a fist and give off a distinctive odor. Since these "mushrooms" don’t completely emerge from the ground, they have traditionally been sniffed out by pigs or trained dogs.

The requirements for growing the black Perigord truffle, Tuber melanosporum Vitt., include choosing an appropriate host plant (usually oak or hazelnut), inoculating its roots with the spawn, and planting it. Frank Garland planted his first inoculated trees in 1980 and harvested the first black truffles grown in the U.S. on October 23, 1993. He has written a production guide based on his experience.(Garland, 1996) Garland also has a consulting business and sells inoculated trees.

One Oregon tree farmer in prime white truffle country found a low-fuss method of cultivation. The white truffle, Tuber gibbosum, is a mycorrhizal species associated with Douglas fir and other conifers. This farmer uses a backpack sprayer to apply a slurry made of truffles and spores at the roots of conifers. The inoculated areas have produced between 300 to 1000 pounds per acre per year, significantly more than the unsprayed areas.(Arnold, 1996)

The truffle industry has developed rapidly in Australia and New Zealand. New Zealand’s efforts, as reported by Dr. Ian Hall, were begun in 1987, with harvest recorded on June 29, 1993, just months before Garland found his first truffles in North Carolina. (See <www.fungifest.com/articlep1021.html>.) Australian researchers also report success in their cultivation efforts, summarized in several articles available on the Web. The articles are found by searching the following main pages for "truffle" or "Tuber melanosporum":

www.crop.cri.nz

www.rirdc.gov.au/reports

The Black Truffle (Hall et al., 1994) is out of print, but it was converted to CD ROM format in 2001 and is available for NZ$49.95 through the Internet at <www.crop. cri.nz/psp/products/truffle.htm>. Chapters cover the symbiotic partnership between truffles and their host plants, his• • establish and manage a plantation, climatic and soil requirements, and cultivation and harvesting.

Studies have revealed a lot about the conditions necessary to bring truffles to early fruiting and then to significant production levels. However, because of the crop’s extremely high value and because each success has required an investment of considerable time, it is understandable that some of this information is considered proprietary. Even when fruiting begins, growers themselves may not be able to accurately identify what contributed most to the truffles’ growth.

Each new truffle enterprise is an experiment based on what has already been reported. Check this Web site maintained by a group of scientists investigating truffle cultivation: <www.truffle.org/tuber_directory/>.

Consider combining the production of truffles with the sale of nuts from the host trees, growing annual or perennial crops between the trees, or grazing ruminants among them—sheep have been credited with increasing the French wild-harvested crop yield.(Ludmer-Gliebe, 1997) These or other agroforestry options could provide additional sources of income during early, non-fruiting years and in the seasons when truffles do not produce.

Other Mycorrhizal Species

Mushroom researchers continue to investigate the cultivation of other species for the

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Chanterelle Mushrooms

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commercial market. A loosely organized group of international scientists meets intermittently to share their research. The Web site maintained for this scientific endeavor is <www.mykopat.slu.se/mycorrhiza/edible/home.phtml>.

Until commercial production systems are developed, mushrooms such as chanterelles and matsutake (pine) mushrooms will continue to be collected from the wild for sale to the specialty mushroom market. The harvest of wild mushrooms is strictly regulated in some states. Check with your state department of agriculture regarding laws that apply. You would be wise to carry liability insurance and to be absolutely certain of the identity of mushrooms you sell. Mistakes can be fatal to the consumer. Finally, the forest environment that supports the growth of wild mushrooms is a fragile one. Learn how to conduct your foraging business in a way that protects future harvests.

Mushroom the Journal (see Resources) provides excellent information on wild mushrooms. There are also many local mycological societies that schedule "forays"—trips to known mushroom habitats—where the inexperienced forager can learn about various species and how to identify them.

Pest Management

Integrated pest management (IPM) is a least-toxic approach for managing any pest. IPM views pests as a natural part of the farm environment. The integrated management of a pest is accomplished by altering the environment to the disadvantage of that pest. In order to accomplish this, you have to be able to identify what pests are active, how many there are, and how many it takes to hurt your profits. If you know the life cycle of each problem organism, you can take measures to make it hard or impossible for it to complete its life cycle. You may b

oyster-mushroom

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