Mushroom Log Cultivation
Selection and Cutting
The best times for cutting logs are either in the winter months for spring inoculation or from August through October for late summer or fall inoculation. Oak is particularly good for the cultivation of most mushrooms though many other hardwoods work well also, such as poplar, aspen, sugar maple, willow, alder and birch, among others. Other species yield less mushrooms with redwood, cedar, madrone and manzanita yields being negligible or non-existant do to their resins being fungicidal. Conifers are to be avoided for the cultivation of most mushrooms with the exception of chicken of the woods and some species of oyster mushrooms such as Pleurotus pulmonarius: commonly known as the phoenix oyster. The bark of your selected logs should look healthy, without trunk rot or leaf blight. The logs should have medium thick bark; handle them gently to preserve the bark as a barrier to other fungi and possible microbial competitors. A good general size for logs is 2" - 8" in diameter and 24" - 48" long.
It is ideal to inoculate within three weeks of cutting. Delays can result in lower yields from the logs becoming too dehydrated and colonized with other microorganisms. If you cannot inoculate you logs right away, first make sure the bark is dry, and dead-stack them like firewood over two horizontal logs or bricks off the ground in a shady spot, and lightly cover them with plastic to keep off the rain. Rain on the logs reduces drying, but accelerates rotting. Dead trees can not be used for inoculation due to them most certainly being already colonized by other fungi.
With a 3/8 in. bit drill 1¼ in. deep holes for plug spawn. Situate each hole about 4 - 6 in. apart within a row. Leave approximately 2 - 3 in. between the rows and offset the holes so that they form a hexagonal pattern. A 4 in. diameter log will need 6 rows; a 5 in. diameter log will need 7, and a 6 in. diameter log will need 9 rows. A large stump usually requires 100 to 200 holes arranged in a similar hexagonal fashion around the trunk and with holes on the top of the stump as well. Spawn for all mushroom varieties are inoculated into logs and stumps in this manner.
When using plug spawn hammer the plugs into the holes flush with the bark. Next cover the plugs, and if you're feeling ambitious, the cut ends, with cheesewax. To do this, melt the wax in a pan which can be maintained at 300 degrees Fahrenheit. An electric frying pan with a thermostat control works well for this. If inoculating away from electricity, using a camp stove, make sure that the wax is hot when you apply it; otherwise, the wax will not create a tight seal and can easily fall off. The cheesewax will smoke lightly when it is adequately hot. The wax can be applied with a foam brush or dauber.
Once the logs are inoculated stack them in a shady, sheltered spot. If necessary, use 60% shade cloth, the tough woven kind that will not tear when dragged over logs. Stack in a pile over horizontal logs or bricks and cover loosely with plastic to keep the rain off while retarding evaporation. The logs are well-hydrated with fresh sap for the first two or three months, but after that, moisture-loss becomes excessive. Ideal stacking locations are shady, wind-protected, and moist, like north slopes. In Winter when the leaves are off the trees, 60% shade cloth, burlap bags, or pine boughs may be needed. Evergreen trees make an ideal cover. Check on your logs regularly to ensure that they are moist. If your logs ever seem dry, water them. Although they obtain their nutrients differntly from plants, your mushrooms need water to stay alive just like plants. The most common cause of failure to produce mushrooms is the moisture inside the log dropping too low, causing the mycelium to be stunted in its propagation, become stressed and contaminated, or die from dehydration. You need to soak your logs using a sprinkler or hose during colonization, every day in dry Summer spells. However, it is very important to allow the bark to dry in between waterings.
If the bark stays wet continually, fungi and bacteria in the bark prosper, while the mushroom mycelium in the log declines. Some competitors decimate shiitake, like the forest-green fungus Trichoderma. In all cases, prevention is best - if you start with healthy trees and manage your logs carefully, you will minimize any problems and have good mushroom crops off the same logs for years.
Colonization requires at least one warm season for shiitake, oyster, and other log-grown mushrooms. Fruiting is near when white splotches of mycelia appear in an irregular white ring at the ends of the logs. Mycelia will not colonize dry ends of the log, though the logs may be ready. A good strategy is to let nature take her course, allowing the first couple of harvests to occur naturally as Fall or Spring rains thoroughly soak the logs. The first small flushes of mushrooms will appear in those logs that are ready to support them. Thereafter, you can choose to let Nature continue to fruit the logs with a minimum of management (mostly an occasional soaking in hot, dry weather), which will give you lots of mushrooms in the Spring and Fall, and very few or none in the Summer and Winter. The alternative strategy is favored by commercial cultivators, for whom reliable week-in, week-out supplies of mushrooms bring the highest prices from chefs and produce managers. This strategy is described next.
When a fully colonized log is immersed in clean water a few degrees cooler than the ambient air (tap water usually is) and soaked for 24 hours, this combination of extra water and cold simulates the stress of Spring and Fall conditions. The log begins to fruit within one or two days, and harvests continue for 7 to 10 days. Mushrooms are harvested at least once a day, when their caps are about 80% unrolled. Cut the stem flush with the bark with a sharp knife. After a few days, mushroom production gradually tapers off, and the logs need time to digest more wood for the next fruiting. Mycelia (and mushroom fruiting) becomes dormant when the average temperature approaches the low 50's.
Logs generally begin producing 6 months to 1.5 years after inoculation; after which, they usually continue to fruit for 4 years producing 1-2 lb. per year. Each log usually produces 2.5 lb - 4 lb over its lifetime depending on size and care.