Mushroom Pests

Abstract

More than a dozen species of edible fungi are cultivated worldwide. The white button mushroom, Agaricus bisporus, is cultivated in over 100 countries and accounts for approximately 70% of all mushroom production (Chang and Miles, 1989). A. bisporus mushrooms are cultivated on pasteurized compost prepared either from horse manure or agricultural wastes such as wheat or rice straw. The raw materials are mixed with nitrogen-rich materials such as chicken manure or chemical fertilizers and wetted in long stacks on concrete floors ‘out-of-door.’ The stacks are shaken up and re-stacked (‘turning’) at 2–3 day intervals. After 7–14 days, the compost is moved into rooms fully equipped with environmental controls and is pasteurized at 55–60°C for periods up to 8 h. This process kills most pathogens, nematodes, and insects. Following an appropriate cooling period, the pasteurized compost is used to fill trays, built-in shelves, or tunnels, and inoculated with mushroom mycelium (‘spawning”). A recent trend is to spawn compost in tunnels where it is pasteurized and moved to shelves or trays only after the mushroom mycelial colonization (‘spawn-run’) is complete. Mushroom mycelium colonizes the compost within 10–14 days at 24°C. To induce fructification, compost is covered to a depth of 3–5 cm with a layer of soil, or more often a mixture of moss-peat and chalk. This is called the casing layer. Mushrooms start to appear from the surface of the casing within 12–15 days after its application. At first to ensure good growth of mycelia into the casing layer, the temperature is kept at about 20°C, but after a few days, when fruiting body initiation has begun, the growing rooms are maintained between 16 and 20°C. Ventilation with fresh air is important but air humidity has to be kept above 90%. Following the production of the first mushrooms, the crop is produced in a succession of fruiting bodies known as ‘flushes.’ Each flush of mushroom is harvested over a period of about 4 days, and flushes occur at intervals of 7–14 days. A single crop may occupy a growing room for 7–10 weeks.