While they are considered fresh produce, mushrooms are neither fruit nor vegetable, but are a fungus. Mushrooms are extremely versatile and can serve as a tasty food source as well as a useful fertilizer for trees and soil. Unlike most other produce, mushroom growth is actually hampered by sunlight. Instead, mushrooms feed on decaying organic matter in compost and thrive in the dark.
Cultivated for centuries in China, there are more than 38,000 varieties of mushrooms (some highly toxic), only about 300 species are edible. Before the advent of commercial agriculture, mushrooms were typically gathered in the wild and some varieties are still harvested this way. Good quality, edible mushrooms can be difficult to grow; the cultivation process is not only labor intensive but highly sensitive to changes in the composting material.
Mushrooms are a staple in many international cuisines, particularly Asian dishes, which have been responsible for the worldwide popularity of shiitake mushrooms in particular. The edible portion of a mushroom is the toadstool, which includes the stem and the cap. The wheel spoke-like underside of the cap contains the gills, which hold spores for reproduction.
References: Agricultural Marketing Resource Center, PennState Extension, University of California Cooperative Extension, University of Florida/IFAS Extension, Western Growers Association.
TYPES, VARIETIES & CUTS
Popular edible mushroom varieties include button, portabella, oyster, enoki, shiitake, crimini, lobster, porcini, and morels. Button mushrooms (Agaricus bisporus) are the most commonly grown in the United States. These are usually classified according to color, breaking down into whites, creams, and browns.
Less than 15 mushroom types (including include button, shiitake, enoki, porcini, straw, oyster, common oyster, golden top oyster, phoenix tail, bear head, wood ear, hair wood ear, silver ear, and ling zhi) can be grown domestically due to the difficulty of cultivation. Pennsylvania leads the nation, producing two-thirds of U.S. production.
Morels, oysters, and chanterelles are often gathered in the wild, especially in the northeast and Pacific Northwest of the United States. Matsuke, white truffles, and black truffles are exclusively gathered from the wild as they need to interact with animals and trees in their natural environment to thrive.
References: Agricultural Marketing Resource Center, University of California Cooperative Extension, University of Florida/IFAS Extension, University of Illinois Extension, Western Growers Association.
PESTS & DISEASE
With indoor growing the norm and pasteurization of the mushrooms’ growing environment, pests are not a significant problem–though various flies, gnats, mites, and millipedes, as well as nematodes will affect the growing process.
More common is postharvest damage from rough handling or improper cooling. Mushrooms kept in environments that are too warm and dry will develop blackened stipes and gills and curled caps. Mushrooms that are bruised through rough handling develop discolored patches. Although mushrooms are a form of fungus, they are still susceptible to a range of fungal, bacterial, and viral diseases including various mold, mildew, spot, and blotch outbreaks. Bacterial blotch and other bacterial diseases can lead to spoilage if not eliminated during growth and harvest.
References: PennState Extension, UC Davis Postharvest Technology website, USDA.