Alaska Pioneer Fruit Growers Association

RAISING OYSTER MUSHROOMS ON COTTONWOOD LOGS

August 9, 1997

 

Dwight Bradley

 

Many people who came to the 1996 apple tasting at the Bradley homestead saw our experimental mushroom farm. Now, nearly two years after first inoculating the logs, we are getting our first crop. Pleurotu ostreatus, the oyster mushroom, is a delicious edible mushroom that grows on dead hardwood trees. Oyster mushrooms can be substituted for agaricus, the ordinary store-bought mushroom. Most people like them as well or better. Back in New Hampshire and Maine, it is a common, unmistakable species that beginning mushroom hunters can learn to identify and eat safely. In Alaska, we’ve encountered it on cottonwoods along lakeshores in the Matanuska Valley, but it is not very common. Oyster mushrooms are grown commercially and are occasionally sold at Carrs in Anchorage for a lot of money ($16/lb when I checked once).

 

To grow oyster mushrooms, you first need to buy spawn from one of several commercial mushroom suppliers. The spawn is a white, moldy-looking fungal growth that permeates sterilized grain in a quart-size container. It costs about $5 per quart, enough to inoculate five to ten fireplace-size logs. The best time to cut the logs is during the winter, when there are few fungal spores (potential contaminants and competitors) in the air. Cut live trees that have no obvious health problems. Dead trees will not do, because they are apt to host many competitor fungi already. A cottonwood tree about 6-8 inches thick at the base seems to work well. Buck into 24² lengths. Score the ends of each log with the tip of the bar to create kerfts about an inch deep. To inoculate the logs, spread spawn on both of the cut ends and into the kerfs; the spawn should be one-quarter to one-half inch thick. Now wrap the whole log in stretchy plastic wrap so that the spawn is held tightly against the exposed wood. The whole operation takes less than five minutes per log once you get the hang of it. Put the logs in a warm place, such as a furnace room, for 6 weeks.

 

I inoculated 100 logs during the winter of 1995-96. The next summer, I put them outdoors in a grove of trees, out of the direct sun. I cut the plastic off the tops and bottoms and set the logs upright in rows. I put some composted horse manure on the forest floor to level it out so the logs wouldn’t tip as easily; I suppose leaves would have worked just as well. I ???? the rest of the plastic wrap on the logs to try to keep them from drying out during the annual May-June drought. The summer of 96 came and went with no mushrooms. Finally, after another winter, and another dry summer, the mushrooms started sprouting. The first ones appeared as tiny dark gray buttons on about September 3 and the first harvest was on Sept. 6. Now, on Sept. 10, nearly half the logs have oyster mushrooms growing from them. The biggest mushrooms are about 4-5 inches across. So far we’ve harvested about 20 lbs and the total yield will probably approach 100 lbs.