Mites belong to the spider family. They are eight-legged compared to insects which are six-legged. They are very small and are usually not noticed until large numbers are present. Many different kinds of mites are encountered during mushroom cultivation process. Some mites feed on fungi and bacteria that exist in great amounts in decaying organic materials used as a substrate in mushroom production. Other members of mites are predators that mainly feed on nematodes and smaller mites. Only a few of them are considered as mushroom pests. These include mushroom mites or tarsonemid mites (Tarsonemus myceliophagus) and red pepper mites (Pygmephorus sellnicki). The mushroom mites are so small, that they are not seen with a naked eye. They are shiny, light brown in colour feeding on the mushroom mycelium and mycelium of many other competing fungi present in the substrate. They gnaw the bases of mushroom stipes (stalks of mushroom) which in result become rounded and obtain a reddish-brown shade. The amount of damage they bring to the growing crop will depend on the time and degree of infestation. If a large population of mites enters the batch at spawning, the damage can be significant.
Red pepper mites got their names from their reddish-brown colour and are often found moving on the mushroom caps or the casing surface. These mites are not regarded as primary pests, their presence is usually an indicator that Trichoderma (green mould) is present in the compost. These mites feed on various weed moulds but not mushrooms, thus their presence indicates that the compost is unsatisfactory. They are yellowish-brown in colour, 0.25 mm in length and have a flattened appearance. They spread spores of Trichoderma from bag to bag. They feed on competing fungi and that is why their presence indicates poorly prepared compost and possible presence of Trichoderma. They reproduce very fast one female can lay up to 160 eggs within 5 days. They cause browning of mushroom heads and promote the spreading of green molds not only in the infected room, but also in the whole farm. When their population is high, they cause discomfort and even allergy to mushroom pickers at work.
- Maintain strict hygiene in the mushroom houses. This includes thorough cleaning of all machinery, equipment and rooms that were used during the spawning process, steaming the rooms in the end of the cultivation cycle at necessary temperature, and using disinfectants such as household bleach (sodium hypochlorite) (e.g. Teepol) to clean all working surfaces and implements. Workers should wear clean clothes and dip their shoes in a disinfecting solution (sodium hypochlorite) before entering the growing rooms
- Keep straw and manure away from mushroom growing houses
- Use properly pasteurized substrate (compost)
- Control mushroom flies
- Remove spent compost from the farm. It can be used as manure for other crops