There are some pests that are often noticed in association with shiitake mushroom production. Fortunately, there are not a large number of pests that cause serious problems. The principle problem with shiitake may be from other fungi that affect the log and shiitake mycelia. Because the fruiting bodies grow quickly on the log and should be harvested quickly before the mushroom caps get flattened out, there is not usually a lot of time for pests to do a lot of damage to the actual mushrooms. Here are a few of the most common pests (Bak and Kwon 2005):
Beetles – Some types of beetles may cause damage by digging under the bark in the larval phase, or introducing other fungi. If the bark falls off the log, it will dry out and the shiitake will die. Prevention: If beetles have been a problem in the past, you might consider covering the logs with a mesh to keep beetles from laying eggs on the logs.
Soldier Beetles – These small bugs can be seen in the gills on the underside of the mushrooms. They do not harm the mushroom, but actually eat tiny mites that cannot be seen with the naked eye. Prevention: Harvest mushrooms quickly while caps are still rounded. Treatment: After harvest, it is possible to blow the beetles out of the mushrooms with a hair dryer.
Termites – Termites are not usually a problem, but can destroy the log. Prevention: Keep logs off the soil by using pallets or something else.
Mammals (mice, squirrels, deer, rabbits) – Some wild and domestic animals have been noted feeding on shiitake. Prevention: A variety of techniques may be effective, including fences, wire screens, or other barriers; or repellents. Harvest mushrooms quickly.
Bak, WC and Kwon H. 2005. Biology and control of pests and diseases in shiitake log cultivation. Mushroom Growers’ Handbook. 152-161.