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Growing Shiitake Mushrooms In The Woods

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This article comes from the NOFA/Massachusetts 2013 December Issue Newsletter

Presented and reviewed by Ross Conrad

Shiitake logs

Shiitake mushrooms are among the most widely grown mushroom in the world, second only to the common button mushroom. Log-grown shiitake mushrooms are relatively easy to raise, certify organic, and use to create a small-scale commercial operation if you have the basics: space, shade, access to hardwood logs and water. Shiitake growing is a great way to make use of forest or marginal land, such as steep hillsides that may not have other uses.

Log-grown shiitake mushrooms tend to be thicker and more flavorful than commercial shiitake grown in sawdust. Hardwood logs, or bolts, for growing mushrooms can be cut from trees on your own land, bought from someone else (usually for $1-$2 per bolt), or occasionally gleaned from road crews clearing trees along your street. The top branches from firewood or lumber trees work wonderfully. Logs from trees cut in late winter or early spring that are full of sap are preferred.

In Japanese, “shii” translates into oak and “take” means mushroom. Thus, red and white oak are the native woods for growing shiitake mushrooms, however they also grow extremely well on sugar maple (Acer saccharum), American hornbeam (Carpinus caroliniana, aka ‘musclewood’), hophornbeam (Ostrya virginiana, aka “hardack’), and beech (Fagus grandifolia) trees. Most folks use logs that range in diameter from a minimum of 3 to a maximum of about 8 inches and are about 3 feet long. This provides a sizable log that will not dry out too quickly but is still relatively easy to move around by hand.

Once obtained, allow the logs to sit in a shaded area for anywhere from about 3-8 weeks before inoculating them with shiitake spawn. While a regular drill will work for drilling the inoculation holes, for commercial production a high-speed drill or angle grinder with a special drill bit and drill stop should be used to speed up the process. The size and depth of the holes will depend on the type of spawn used. Once the holes are drilled, fill them with the spawn in order to bring the shiitake mycelium in contact with its new food source—the log.

Once filled, the holes and areas where the tree bark has fallen off should be coated with a layer of melted food-grade wax. This will help to retain moisture and prevent competing fungi from contaminating the log. The logs are then left in a shaded area for 6-18 months to allow the mycelium time to grow throughout the log. This is known as the ‘spawn run’. Many growers will stack the logs on top of each other in rows of four or five for four or five levels high. This type of stack, known as a crib or rick stack, makes use of vertical space to compactly store large numbers of logs. Within 4-8 months, the white mycelium growth of the shiitake should be visible on the ends of the bolts indicating healthy colonization of the logs.

For commercial production you will want to stimulate a set of logs to fruit all at once so that significant numbers of mushrooms are ready to pick and deliver around the same time. This is accomplished through the forced fruiting method of production known as shocking. Logs are submerged in cold water for 12-to-24 hours. The change in temperature and the increase in the log moisture content stimulates the shiitake mycelium to fruit. During the fruiting and harvest stages logs are stacked differently in order to aerate the logs and make the mushrooms easy to see and pick. Stacking the logs against a fallen tree trunk or a sapling lashed horizontally between two trees in an A-frame configuration works well for this. Depending on the temperature and humidity levels, shiitake may be ready to harvest anywhere within 4-12 days after shocking.

Shiitake mushroom are ready for harvesting when the veil under the cap is broken and the cap is about 70-75 percent open. Mushrooms with caps that are fully open are still edible, but since the mushroom will continue to mature after harvest, picking the fruit while the edges of the cap are still slightly curled under ensures that your customer will receive the highest quality mushroom you can offer. Logs can be allowed to sit and fruit naturally following a heavy and lengthy rainfall. Natural fruiting will result in fewer mushrooms, but the mushrooms will tend to be significantly larger than those that are produced from logs that are forced to fruit through shocking. While much depends on the strain of Shiitake being grown, most logs should be allowed to rest for about 8 weeks before being shocked again for a second harvest. Keep harvests to twice a season if you want logs that will last for four or more years.

Keep in mind that the actual process of producing log-grown shiitake mushrooms tends to be a bit different for each grower as changes are made to accommodate each producer’s climate, land, and resources, as well as spawn type and markets. This short outline of the process should give you a good idea whether log-grown shiitake mushrooms will fit well into your operation.

Some suggested resources:

Northern Forest Mushroom Growers Network: http://blogs.cornell.edu/mushrooms/factsheets/

Field and Forest Products

N3296 Kozuzek Rd.

Peshtigo, WI  54157

800-792-6220

http://www.fieldforest.net

 

American Mushroom Institute

One Massachusetts Ave, NW, Ste. 800

Washington, DC 20001

202-842-4344

http://www.americanmushroom.org

 

Kozak, M.E., and J. Krawczyk, 1993.

Growing Shiitake Mushrooms in a Continental Climate.

2nd Edition. ABC Printers, 3210 Hall Ave., Marinette, WI 54143

 

Przybylowicz, P., and J. Donoghue. 1990.

Shiitake Growers Handbook.

Kendall/Hunt Publishing Co., Dubuque

 

Kozak, M.E., and J. Krawczyk, 1991.

Year-Round Shiitake Production in the North.

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