A Small-Scale Agriculture Alternative: Shiitake Mushrooms

Shiitake (pronounced "shee-tah-kay" and spelled the same whether singular or plural) are said to be the favorite mushroom in Japan. Worldwide production is second only to the common white button mushroom found in most grocery stores in the United States. Besides Japan, other large producers include China, Taiwan and Korea.

Since 1972, when the U.S. Department of Agriculture (USDA) first allowed shiitake spawn into the United States, production here has grown steadily. During the 1991-92 season, USDA's National Agricultural Statistics Service (NASS) estimated that over 2.7 million pounds of shiitake were grown in the United States. This compares to an estimated 738.8 million pounds of the common button mushroom. The current NASS statistics (published each August) can be purchased from ERS-NASS, P.O. Box 1608, Rockville, MD 20849-1608 for $6.00.

Jerry Larson, the International Trade Manager for the Oregon Department of Agriculture (121 SW Salmon St., Suite 240, Portland, OR 97204-2987) believes that the market potential for U.S.-grown shiitake has hardly been touched. He reports that the U.S. imports 14,000 metric tons of dried shiitake from Japan, Taiwan and Korea each year. If these were fresh mushrooms, this would amount to 126,000 metric tons (nearly 100 times the current U.S. fresh production level).

Growing Shiitake

Shiitake can be grown either on natural logs or on artificial logs made of a special combination of oak sawdust, bran, millet and other additives. Most small-scale farmers will want to start with natural logs because they require less environmental control. Further information on sawdust culture can be obtained from Professor Dan J. Royse, at Pennsylvania State University (211 Buckout Laboratory, Penn State University, University Park, PA 16802).

There are five basic steps in cultivating shiitake on logs:

Ordering good quality culture, which is called spawn or inoculum, so that it will be on hand when needed. The mushroom that will grow from the log is the fruiting body of the whole fungus. Most of the fungus is a mat of white strands (mycelia) that grow through the log to collect the nutrients necessary for fruiting. The spawn which you will purchase is nothing more than a pure strain of living mycelia, growing either in sawdust or in hardwood dowels. Contact your County Extension Agent for help in locating a spawn supplier near you.
Obtaining suitable hardwood logs. Usually oak, maple, beech, ironwood, chestnut or alder are used. The logs are cut green during the winter when the sap is down and are cut to 3- or 4-foot lengths for easy handling. Diameters from 2 to 6 inches seem to work well. Be careful to avoid damaging the bark. Torn bark can allow other organisms to enter the log and compete with the shiitake for nutrients.
Inoculating the logs. Inoculate the logs with the spawn between 1 and 3 weeks after cutting to ensure optimal moisture content. Inoculate the log by drilling holes partway into the log. Then carefully packed these holes with the spawn and seal them with wax to retain moisture and keep out competing organisms.
Allowing shiitake to colonize the wood. Once the mushroom has been introduced to the log via inoculation it takes 4 - 9 months, depending upon climate, for the mycelia to spread throughout the log. During this "spawn run" period, the logs are stacked and shaded to avoid moisture loss.
Inducing fruiting. To induce fruiting the logs are soaked then shaded to keep the moisture level up until fruiting begins. Yields are quite variable. In some cases the spawn will not run through the log and no mushrooms will be produced. The highest yields are only attainable when all conditions are near ideal. The logs can be refruited several times without additional inoculation and can produce mushrooms for several years depending upon how often they are fruited.

There are several additional steps that must be pursued by an entrepreneur to bring the shiitake crop to the market and ultimate sale. Crop harvesting, packaging, storing, transporting, and marketing are some of the vital and important steps that are necessary. However, there are a host of different procedures practiced because factors such as the growers location, time limitations, financial considerations, etc. necessarily dictate the technique pursued.

Information Sources

Several books are available that can provide additional details on growing shiitake. Among them are:

Growing Shiitake Commercially by Bob Harris
The Mushroom Cultivator by Paul Stamets and J.S. Chilton
Growing Shiitake Mushrooms in a Continental Climate by M.E. Kozak and J. Krawcyzk
Shiitake Grower's Handbook: The Art and Science of Mushroom Cultivation by Paul Przybylowicz and John Donoghue

A 13-1/4 minute video on "Growing Shiitake Mushrooms" is available for $10 from the Cooperative Extension Programs of Georgia's Fort Valley State College and North Carolina A&T State University. It is part of a video library they produced on money-making ideas for small-scale farmers. (Checks should be payable to NC A&T University CEP and sent to Director, Extension/Research Communications, NC A&T University, P.O. Box 21928, Greensboro, NC 27420.)

Economics

The costs of producing the mushrooms vary considerably. Major items to consider are the cost of the wood, the cost of the spawn, and the cost of labor. Typically labor will be the largest consideration.

Returns are also quite variable and depend heavily upon your growing climate. The Forest Resource Center reported results of field trials in the March 1992 edition of their newsletter, Shiitake News. Depending upon the species of log and the strain of shiitake used, it reports yields of 0.4% to 12.6% of the green weight of the logs. With a cord of oak which weighs 2,200-pounds and contains 300 logs and an average yield of 7%, one could expect to grow 154 pounds of shiitake over 3 growing seasons. At $4 per pound, this cord would gross $616 over three years. These are conservative estimates based upon the Minnesota experience. Higher yields, on the order of 20% of the weight of the logs, can be produced in warmer, more humid climates and with the proper choice of logs and spawn.

Production Scales

Kenneth F. Konsis of the Vermillion County Conservation District in Westville, IL reported to the 1990 Illinois Specialty Growers Convention that for large profits a 3000 log operation is needed. However, he also recommends starting in the 100- to 500-log range and adding more as desired. This advice is echoed by Ron Snyder, Coordinator for the Geode Resource Conservation and Development (RC&D) office in southeast Iowa.

NASS does not attempt to track production from growers with fewer than 200 logs. The agency reported 458,000 logs under production and 172 growers in the United States during the 1991-92 season. The average grower is thus using around 2,700 logs.

Market Prices

Wholesale market prices for fresh shiitake vary seasonally and with the market serviced. During the fall and spring when most outdoor growers are picking their mushrooms, prices tend to be lower (say $4 per pound). In the winter and summer, prices tend to be higher (as high as $7.50 per pound) since only those with climate-controlled growing facilities will be producing the mushrooms.

The 1991-92 NASS report mentioned above showed the average price nationwide for shiitake at $4.11 per pound.

Jim Gwynn of the USDA's Agricultural Marketing Service's Food and Vegetable Division (Market News Branch, Room 2503-S, P.O. Box 96456, Washington, DC 20090-6456) reports that AMS has employees in most major markets obtaining market prices daily. Daily reports can be obtained by subscription at $15 per month per market city. Weekly reports are $8 per month. Markets currently reporting shiitake sales include San Francisco, New York, Chicago, Atlanta, Boston, and Los Angeles. The lack of reports from other markets indicates potential opportunities for growers in those areas.

Pluses for Small-Scale Farmers

Kenneth F. Konsis, in the report mentioned above, states that shiitake growing might fit well with other goals of small-scale farmers. He suggests thinings from commercial woodlots can be used for shiitake logs. He also notes that in many cases trees can be cut at the 6- to 8-foot height and will resprout at that height without damage by animals. The trees can then be used as living fence posts and provide a continuous supply of shiitake logs.

The Forest Products Lab of the USDA Forest Service (One Gifford Pinchot Drive, Madison, Wisconsin 53705-2398) has a shiitake fact sheet in its free Techline - Microbial and Biochemical Technology series. FPL suggests that smaller diameter hardwood trees and limbs and tops of larger trees are one of the most under-utilized forest materials currently available and that shiitake growing is a viable use of those materials. The factsheet notes that shiitake cultivation is expected to be an excellent growth industry over the next several years.

Marketing Points

Shiitake have some strong selling points. Fresh, the caps, 2 to 5 inches in diameter, have a chewy texture and a full-bodied aromatic flavor. They are low in calories (125 per fresh pound) and low in fat.

Reports indicate that tree-grown mushrooms, like shiitake, have about twice the fiber content of the common white button mushroom (Agaricus bisporus). The particular type of fiber found in these mushrooms feeds the beneficial bacteria in the colon and enhances colon health.

According to Dr. Shu-Ting Chang, Professor of Biology, Chinese University of Hong Kong and Dr. Philip G. Miles, Professor of Biology at the State University of New York in Buffalo (in their 1990 book Edible Mushrooms and Their Cultivation ), shiitake contain all of the 9 essential amino acids of protein required in the human diet.

More Information

The American Mushroom Institute (907 East Baltimore Pike, Kennett Square, PA 19348) publishes Mushroom News and Mushroom News Flash for their members on a monthly basis. Associate memberships are $300 per year and grower memberships start at $350 per year.

Successful Farming Magazine has published two articles on shiitake in its ADAPT series. One describes the initial experience of the Geode RC&D's shiitake project. The second shares the experience of a Virginia shiitake farm. Copies of these articles can be obtained from Betsy Freese at Successful Farming (ADAPT), 1716 Locust Street, Des Moines, IA 50309-3023.

Shiitake News is published three times a year by the non-profit Forest Resource Center at Rt. 2, Box 156A, Lanesboro, MN 55949. The 16 page newsletter costs $25 for an initial subscription which also includes three back issues. Renewals are $15 per year.

The Mushroom Growers' Newsletter (P.O. Box 5065, Klamath Falls, OR 97601) is published monthly and includes production and marketing information (including prices) on other cultivated mushrooms as well as shiitake in its 8 pages. The current issue is $4.00, back issues are $3 each and subscriptions are $35 per year.

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By Jerry Haugen, P.O. Box 5065, Klamath Falls, OR 97601 and George B. Holcomb of the Office of Public Affairs, U.S. Department of Agriculture, for USDA's Office for Small-Scale Agriculture (OSSA), Howard W. "Bud" Kerr, Jr., Program Director. OSSA's address: Ag Box 2244, Washington, D.C. 20250-2244. Telephone: 202-401-1805; Fax: 202-401-1804.

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Mention of commercial enterprises or brand names does not constitute endorsement or imply preference by the U.S. Department of Agriculture

June 1993