Selecting Logs for Mushroom Growing
There are many mushroom varieties that grow on logs - Shiitake, Oyster, Lion's Mane, Comb Tooth, Reishi, Olive Oysterling, and Nameko. Cultivating mushrooms on natural logs is a wonderful long-term method for mushroom production. A prime Shiitake log can fruit for 8 years or longer! Not all trees make good mushroom logs. As a general rule, hardwoods are ideal. Different tree species are better for certain mushrooms than others and there are a few recommendations for selecting ideal logs. See the chart below for some recommendations:
Healthy, living trees, free from any obvious disease or insect problems, should be cut during the dormant season. The dormant season is from ⅓ leaf color change in the forest canopy to several weeks before visible bud swell on the twigs in the spring. Once cut, the wood should be aged (cured) for a minimum of several weeks to allow a slight moisture loss from the logs as shiitake cannot invade living or water saturated cells. Drying prevents the wood cells from revitalizing during spawn run. Revitalized cells (usually evidenced by sprouts developing on the logs) leads to poor spawn run and lower yields.
The curing time will vary greatly based on wood species and local environment. A way to check to see of the logs are ready to inoculate is to look at the log ends for cracking. Thin crack radiating from the center of the log to around ⅔ of the diameter are ready for inoculation. If the edge of a dime can be inserted into the cracks and the cracks radiate out to the edge of the log, then the logs may be too dry. This is the only time we would recommend logs be soaked prior to inoculation.
Fall cutting at ⅓ leaf color change is ideal as wood nutrition is at its peak and cell walls are still soft to allow for concentration of sugars to prevent living cells from freezing in the winter. Cells have yet to harden so shiitake spawn run is fast and yields high. In the north where winters are long, the wood can be cut and stored under snow cover until spring of the following year or better yet, inoculated and stored inside a somewhat heated building using the high speed method (eventual link) developed in Japan to encourage spawn run and earlier fruiting for the following season.
Passing summer storms often lead to high winds and fallen limb wood which can be used for cultivation as long as it is 4-6 weeks past the time of total leaf out in early summer. The best management practice for this wood is to leave it lie whole and cut it into logs when the leaves wither and brown. The logs should then be promptly inoculated.