mushroom cultivation

Instead of seeds, mushrooms reproduce asexually through spores. Spores can be contaminated with airborne microorganisms, which will interfere with mushroom growth and prevent a healthy crop.

Mycelium, or actively growing mushroom culture, is placed on a substrate—usually sterilized grains such as rye or millet—and induced to grow into those grains. This is called inoculation. Inoculated grains are referred to as spawn. Spores are another inoculation option, but are less developed than established mycelium. Since they are also contaminated easily, they are only manipulated in laboratory conditions with a laminar flow cabinet.
Techniques

All mushroom growing techniques require the correct combination of humidity, temperature, substrate (growth medium) and inoculum (spawn or starter culture). Wild harvests, outdoor log inoculation and indoor trays all provide these elements.
Wild harvesting
Unbalanced scales.svg
    The neutrality of this article is questioned because of its systemic bias. In particular, there may be a strong bias in favor of USA. Please see the discussion on the talk page. Please do not remove this message until the issue is resolved. (February 2014)

Due to its climate, the Pacific Northwest of the USA produces commercially valuable mushrooms. Valued species include:[3][4]

    American matsutake or pine mushroom (Tricholoma magnivelare)
    Chanterelles (Cantharellus formosus, Cantharellus subalbidus, and Cantharellus cibarius)
    Horn of plenty (Craterellus cornucopioides)
    Boletes (Boletus edulis and others)
    Truffles (Tuber gibbosum and Leucangium carthusiana)
    Hedgehogs / "spreading-hedgehog mushroom" (Hydnum repandum)
    Edible morel (Morchella esculenta)
    Coral tooth mushroom (Hericium abietis)
    Shaggy parasol (Lepiota rhacodes)
    Black picoa (Picoa carthusiana)
    Cauliflower mushroom (Sparassis crispa)

Mushroom gatherers have few requirements to begin business. Gatherers only need to supply funds for possible park fees, knowledge for identifying mushrooms and gathering time.

There are significant disadvantages to relying on natural mushroom production. These sales may be unregulated, placing buyers at risk for buying toxic or inedible mushrooms. By honest error, harvests may include toxic or inedible species. No controls exist to regulate the quality or frequency of harvests, since gatherers rely on favorable natural conditions and weather to produce fruiting. Conflicts may arise between competing gatherers trying to harvest from the same location.

State parks in the Pacific Northwest or elsewhere may charge fees for mushroom gathering permits.[5][6] Appalachia also produces edible wild mushrooms, including chanterelles and morels.[7] Pickers may sell directly to distributors, restaurants, or sell their harvest through roadside stands wherever a natural supply of mushrooms is plentiful.

While there may be concern that harvesting wild mushrooms may exploit or damage a natural environment, harvesting wild mushrooms is different from harvesting wild plants, fishing or hunting animals. In these last three cases, removing individuals decreases the ability of a wild population to reproduce, since fewer adults remain. Removing adults leaves fewer individuals capable of reproducing and reduces genetic diversity.

Harvesting wild mushrooms removes only fruiting bodies and their attached spores. However, the fruiting bodies (mushrooms) have likely dropped spores before harvest time, or will likely drop them en route to the harvester's destination, further expanding the fungi's habitat. Arguably, the practice of mushroom harvesting may actually help the species being harvested. While truffles also represent the fruiting body of a larger underground network, they are an exception, since they rely on animal spore dispersion.

Additionally, reproduction and propagation can still occur by propagation of the parent mycelium. Harvesting removes none of the parent mycelium, which remains intact underground.
Outdoor logs

Mushrooms can be grown on logs placed outdoors in stacks or piles, as has been done for hundreds of years.[8] Sterilization is not performed in this method. Since production may be unpredictable and seasonal, less than 5% of commercially sold mushrooms are produced this way.[9] Here, tree logs are inoculated with spawn, then allowed to grow as they would in wild conditions. Fruiting, or pinning, is triggered by seasonal changes, or by briefly soaking the logs in cool water.[8] Shiitake and oyster mushrooms have traditionally been produced using the outdoor log technique, although controlled techniques such as indoor tray growing or artificial logs made of compressed substrate have been substituted.[9][10][11]

Shiitake mushrooms grown under a forested canopy are considered non-timber forest products[12] In the Northeast shiitake mushrooms can be cultivated on a variety of hardwood logs including oak, American beech, sugar maple and hophornbeam. Softwood should not be used to cultivate shiitake mushrooms. [13] The resin of softwoods will often times inhibit the growth of the shiitake mushroom making it impractical as a growing substrate.[14]

In order to produce shiitake mushrooms, 3 foot hardwood logs with a diameter ranging between 4 and 6 inches are inoculated with the mycelium of the shiitake fungus. Inoculation is completed by drilling holes in hardwood logs, filling the holes with cultured shiitake mycelium or inoculum, and then sealing the filled holes with hot wax. After inoculation, the logs are placed under the closed canopy of a coniferous stand and are left to incubate for 12 to 15 months. Once incubation is complete, the logs are soaked in water for 24 hours. 7 to 10 days after soaking, shiitake mushrooms will begin to fruit and can be harvested once fully ripe.[15]
Indoor trays

Indoor growing provides the ability to tightly regulate light, temperature and humidity while excluding contaminants and pests. This allows consistent production, regulated by spawning cycles.[16] This is typically accomplished in windowless, purpose-built buildings, for large scale commercial production.

Indoor tray growing is the most common commercial technique, followed by containerized growing. The tray technique provides the advantages of scalability and easier harvesting. Unlike wild harvests, indoor techniques provide tight control over growing substrate composition and growing conditions. Indoor harvests are much more predictable.

According to Daniel Royse and Robert Beelman, "[Indoor] Mushroom farming consists of six steps, and although the divisions are somewhat arbitrary, these steps identify what is needed to form a production system. The six steps are phase I co