Introduction

Growing gourmet or medicinal mushrooms (specialty forest mushrooms) as a component of a Forest Farming system can be a satisfying and profitable venture if your forest site has the appropriate conditions and you have the appropriate resources, including a market, to make a go of it. This module should help you determine if “specialty forest mushrooms” are a good option for forest farming under your particular circumstances. You should consider carefully both the pros and the cons of SFM production before you begin. This module will provide a discussion of the critical issues, a video illustrating the the log inoculation process, and other How-to resources for shiitake mushroom production, as well as a step by step guide (including video) for growing Shiitake mushrooms, and links to other resources about shiitake and other specialty forest mushroom production.

Pros and Cons of Growing Mushrooms

The Advantages (Pros)

• Outdoor log-cultivated mushroom are generally considered to be of higher quality and consequently worth 2 to 8 times more money than mushrooms of the same species grown indoors on “artificial substrates” (e.g. pressed sawdust) For example, Shiitake at local big chain supermarket in Ithaca, NY sell for about $5.00 to $7.00 per pound. Log-grown shiitake sell for $16.00 per pound at the local farmers market.
• Mushrooms are increasingly popular not only for gourmet cooking, but also for their health-promoting (medicinal) value. Log-grown shiitake mushroom are nearly twice as high in health-promoting polysaccharides than shiitake grown indoors on artificial substrate (Brauer, et al., 2002).
• Capital investment is much less for outdoor log (or stump, or woodchip) –cultivated mushrooms than for indoor year-round production which requires investment in a climate controlled building.
• Forest stand improvement involves tree thinning and other activities that generate wood that is not suitable for timber. Logs used for Shiitake mushroom production are worth at least five times more than the same log sold as firewood.
• Once a log has been producing mushrooms it may continue to do so for several years in a row.

The Down-Side (Cons)

• Outdoor mushroom cultivation is periodically labor intensive (hard work) during log cutting and inoculation, and later during fruiting.
• After logs begin fruiting daily harvest may be necessary.
• Unless you can get your product to market quickly, refrigerated storage is required.
• Forest cultivated mushroom production is seasonal (unlike year round indoor production).
• Logs must be inoculated soon after cutting from live trees. You can’t use dried logs for anything but “firewood”.

Considerations

• Fungal species (what kind of mushroom) and strain
• Wood or other organic substrate (what kind of tree)
• Environmental conditions, particularly shade and possibly a source of water for occasional irrigation.
• Relatively flat land
• Market

Choosing a Fungal Species

Recommended Species

Our top recommendations for beginners who would like to learn how to grow specialty forest mushroom are shiitake, followed by oyster mushrooms. These two are the most reliable, predictable, and can be grown on natural substrates (wood) commonly available as byproducts of forest farming. Shiitake will take longer (6-18 months) to begin producing on a log of a given tree species but production of mushrooms is likely to last longer – 2 to 4 pounds of mushrooms from a single log over several (3-5) years is realistic with proper management. Oyster mushrooms can be grown on logs of a more limited range of tree species, especially poplar, on which they may begin fruiting with a single growing season (3-4 months. For both shiitake and oyster mushrooms there is a well developed market demand so that you can be assured of getting a reasonable financial return on the time, energy and investment that go into cultivating mushrooms in the woods. More experienced mushroom growers, or beginners who are less risk averse than most of us, have a broader palette of mushroom species to choose from for forest production. These include Maitake (Griffola frondosa), Lion’s Mane (Hericium sp.), Reishi, and Stropharia. The first 3 can be grown on logs similar to the cultivation of shiitake and oyster mushrooms described in the next section, although cultivation of stumps is also a possibility. Stropharia on the other hand is grown on a ground bed of wood chips. All of these more exotic mushrooms usually take longer to begin fruiting than either shiitake or oyster mushrooms and are simply not as reliable. Even the experts experience failures with no readily apparent causes.

Shiitake Mushroom Robert L. Anderson, USDA Forest Service. www.forestryimages.org

Conditions

The need for further research on the production of specialty forest mushrooms, other than shiitake, before it can be considered reliable has been emphasized by Johann N. Bruhn, a leading authority on specialty forest mushroom production at the University of Missouri (Colombia). In his book, What Do We Still Need to Know About Commercial Production of Forest-Grown Specialty Fungi?, he writes, “Although a great deal has already been learned and written about the cultivation of specialty fungi we are still clearly on the steep portion of the learning curve."

It should be pointed out that although mushroom production under forest farming conditions can be a satisfying and profitable experience, most of the species mentioned above including shiitake and oyster give substantially higher yields with greater profit potential when produced “commercially” under intensive, climate controlled, indoor conditions, on artificial, sterilize or pasteurized substrates such as sawdust blocks supplemented with nutrients. For example, the standard “commercial” method for producing oyster mushrooms involves growing spawn in large plastic bags filled with pasteurized straw (Adams. 2000) under controlled environment (warm, high humidity) conditions, rather than outdoors, and hence does not qualify as a forest farming venture.

Riskier Mushroom Species

By all means, we encourage you to experiment with production of other mushroom species, perhaps even from the beginning in addition to shiitake if you are are a risk taker. Once you have learned the basic skills involved in specialty forest mushroom cultivation you may wish to try your hand a production of a number of other, potentially even more profitable than shiitake. Here is a list of possibilities and some sources of information about their cultivation under forest conditions:

References

Mushroom Production Basics on Natural Logs

These next sections will provide you with several resources to help you learn how to grow shiitake mushrooms using the traditional log production methods developed in Japan over a hundred years ago. The same or similar approach can be used for growing oyster mushrooms. The resources provided below include:

1. a brief narrative description
2. a video of mushroom expert John Boyle demonstrating and explaining the production process
3. a list of sources of mushroom spawn and supplies
4. a list of book, pamphlets and website that provide detailed instructions

The information that follows is intended to give you a general introduction to the three main stages of shiitake production, but this is not intended to be a substitute for reading one or more of the excellent books that describe the in detail the factors and variables that can make the difference between success and failure. The video of John Boyle is intended to allow you to look in on an expert conducting a shiitake mushroom workshop to a group of beginners, but the video only covers the inoculation stage of a 3 stage process that includes inoculation, spawn run, and fruiting. We strongly recommend consulting one or more of the excellent books or pamphlets listed in the Additional Web Resourcessection.

Using Logs

Shiitake mushrooms are grown on hardwood logs, usually 4 to 6 inches in diameter, and 3 to 4 feet long. Many hardwood tree species can be used but oaks are considered best, if available. Cherry and ash should be avoided, as should all conifers. Logs must be relatively fresh, cut from live trees and used within several weeks to no more than several months of cutting. The best time to cut logs is while trees are dormant, either late fall or early spring. Since inoculation should be performed only when the temperature is well above freezing, logs cut early in the winter must be protected from excessive drying by shading and/or covering prior to inoculation in the spring. Maintaining relatively high moisture content is one of the most important considerations and many of the specific recommendations given below are based on maximizing log moisture content. Wood that has been allowed to dry below about 29% moisture is well on its way to becoming well seasoned firewood but it won’t grow mushrooms. Another reason to avoid older logs is because other fungi may have already colonized them, so that the shiitake fungus simply can’t compete.

Stacking

There are many different configurations for stacking logs which varies depending on available space and optimal environmental conditions for the logs. “Dead stacking” like firewood, is not recommended since logs need aeration. Crib stacking [picture] is the most efficient use of space but can result in excessive drying of logs at the top of the stack. Stacking in an leaning A-frame [picture] or Lean-to configuration keeps logs adequately aerated, but drying is reduced compared to cribbing since they are lower to the ground, where humidity is higher during the summer and where snow cover can protect logs from drying during winter

The Inoculation Process

The process of inoculation refers to, introducing into the log a pure culture of the vegetative mycellum of the shiitake fungus. This inoculum, which is also called spawn, is produced under laboratory conditions and is best left to the specialist. There are many commercial sources of high quality spawn, and several of these are listed in the Supplies section. Spawn may be purchased from a commercial suppliers in any one of several formuations but sawdust spawn and plug spawn (short hardwood dowels) are most common for log inoculation.

How it Works

• First, drill holes into the substrate log, using a 7/16” drill bit (for plugs) and slightly larger for sawdust spawn to a depth of **. Holes should be spaced about 4 to 6 inches apart within rows and rows should be 2 inches apart. The holes in adjacent rows should be offset to create a diamond pattern.
• Next, sawdust or grain spawn is inserted into each hole. Sawdust spawn is inserted into the holes using a special tool that “injects”. Plug spawn simply involves tapping the short wooden dowel into the hole with a hammer followed. by waxing.
• Finally, after inoculating, each hole is painted over with hot, liquefied, food grade wax. Waxing the ends of the logs by painting with hot wax or dipping the end into a pot of wax is a practiced that is recommend by some, but not experienced growers. Our advice is to wax the ends of the logs if you do not intend to irrigate (sprinkle) your logs during the spawn run period (defined below) to prevent moisture loss from the ends. If on the other hand you do intend to irrigate regularly leave the ends unwaxed so that water can penetrate from the outside in through the ends of the log.

Definitions

Spawn Run

Spawn run is the period of time necessary for the fugal mycelium to completely colonize the inoculated logs. This occurs in a “laying yard”. As mentioned above, the most important consideration during this period is to prevent the logs from drying out. First and foremost this means to keep them out of direct sun. The shade provided by a dense, closed canopy of trees is ideal. If your forest or woodlot is more open than this you may consider hanging an artificial ceiling of greenhouse woven shade cloth (80% or higher light exclusion).

Fruiting

Fruiting refers to the period of actual mushroom formation and harvest, after the fungal mycellim has fully colonized the substrate log. This may occur in as little as 6 or as long as 18 months for shiitake on hardwood logs, or within as little 3 to 4 months for oyster mushrooms on poplar logs. Forced fruiting of shiitake logs can be achieved by soaking them in cool water for 24 to 48 hours. This allows for more control in scheduling harvests throughout the growing season.

One advantage of shiitake over oyster and other specialty forest mushrooms is that temperature sensitive strains of the fungus are available. These strains fruit at different temperatures so that fruiting can be spread out across the entire growing season. There are cool weather strains, warm weather strains and wide range of other strains.

Video on Mushroom Production

Suppliers

• Field & Forest Products
  N3296 Kozuzek Rd. Peshtigo, Wi 54157
  (715) 582-4997 Phone
  
  
• Fungi Perfecti
  P.O. Box 7634, Olympia, Wa 98507
  (206) 426-9292 Phone
  
  
• Hardscrabble Enterprises, Inc.
  RC7 Box 42, Circleville, Wv 26804
  (301) 358-2921 Phone, (202) 332-0232 Phone
  
  
• Mushroom Harvest
  P.O. Box 5727, Athens, OH 45701
  614-448-6105 Phone
  
  
• Mushroompeople
  P.O. Box 220, Summertown, Tn 38483
  (615) 964-2200 Phone & Fax
  
  
• Mycotechnology Services
  43 Randolph Rd., Suite 145, Silver Spring, Md 20904
  (301) 422-6323 Phone
  
  
• Northwest Mycological Cons.
  702 Nw 4th St., Corvallis, Or 97321>
  (503) 753-8198 Phone
  
  
• Shirley Community Development Corporation
  Rt. 1 Box 0 Suite 4/26, Shirley, AR 72153
  (501) 723-8441 Phone
  
  
• Sohns Forest Mushrooms
  610 S. Main St., Westfield, Wi 53964
  (608) 296-2456 Phone
  
  
• Walnut Meadows
  Rt. 3 Box 186, Bruceton Mills, Wv 26525
  (304) 379-3596 Phone
  
  
• Wonshan
  11305 Elk Run Rd., Catlett, Va 22019
  (703) 788-1127