These nematodes feed only on fungi. Two species, Ditylenchus myceliophaguss and Aphelenchoides composicola were identified by researchers as mushroom pests that disturb mycelium growth.
They are characterized by a needlelike mouthpart with which they pierce the mycelial hyphae, inject digestive juices and suck out the cell contents. The cells die, and the nematodes that move from cell to cell destroy the hyphal structures. Moreover, it is assumed that nematodes that pierce mycelial threads, spread bacterial and virus diseases. In areas where mycelium dies, the compost becomes soggy and depressed – an objectionable odor occurs because of anaerobic bacteria activities.
Mycophytic nematodes differ from saprophytic nematodes because they can’t reproduce asexually and don’t form «flickering» columns.
The presence of nematodes on mushroom beds indicates bad cultivation conditions, that is, poor substrate and casing soil preparation and nonobservance of the rules of sanitation and hygiene.
The degree of crop losses depends on the time and level of the initial infection. Infection at spawning time can have an effect on mycelial growth and thus making cultivation unprofitable from an economical point of view. Infection occurring later causes only minor crop losses and goes unnoticed by the mushroom grower.
The nematode control measures are mainly used to prevent their spreading on the farm. This can be achieved, if all operations are carried out properly. Well prepared and pasteurized compost ensures fast and healthy mycelial growth and makes it impossible for the pests to spread.
When it’s suspected that the source of infection is peat (though the bottom layers of peat in beds don’t contain pests), all incoming batches of peat should be tested for the presence of nematodes. Peat that contains pathogenic organisms has to be disinfected and stored in a clean room in order to escape recurring infection.
Growing rooms that are infected with nematodes (if it’s rational) should be kept at low temperatures and dry, as far as it is possible. In the end of the cultivation cycle, they have to be steamed, making sure the temperature remains at the same level in all parts of the room – 70°C.
When steaming is impossible, the compost is fumigated with methyl bromide. All spent compost must be immediately removed from the farm territory.
Measures must be taken to prevent the spread of nematodes by insects, personnel and implements.
At normal hygienic conditions and short cultivation cycles (2-3 breaks), nematodes don’t often cause serious problems. However, mushroom growers must use all resources in order to prevent the occurrence and spreading of nematodes on the farm, hence it’s impossible to control them during the cultivation cycle.