Saprophytic nematodes

Saprophytic nematodes are not considered to be mushroom pests. With their oral cavity that looks like a tube, they suck in organic nutrients and microorganisms and especially bacteria that exist in great amount in compost and in the casing layer. That is why poorly prepared and pasteurized compost is not well suited for the development of mushroom mycelium, but is a favorable environment for the nutrition and reproduction of nematodes that have survived pasteurization. In nonselective substrate, with overly humid areas, nematode population grows incredibly fast. The toxins they release and the increasing number of putrefactive bacteria weaken the mycelium growth. The same thing can happen when water leaks through the casing layer after watering, which causes the mycelium to «suffocate». The compost becomes watery and darkens while there’s an objectionable odor in the room because of putrefactive bacteria.

When the infection is severe, the nematodes swarm in great amounts on the casing surface. They form columns that look like erect waving sticks and thin threads that flicker in the light. In this condition, nematodes are able to adhere to flies, mites and personnel that harvest mushrooms.

The swarming of nematodes of the casing surface

The swarming of nematodes of the casing surface
Moreover, nematodes can have the ability to dry slowly and form a «cyst»; a temporary protective layer due to which they can survive in adverse conditions, being in a dormant state for a long period of time. In this state, nematodes are easily spread by wind. Parthenogenesis, which is the kind of sexual reproduction that allows females to reproduce without males, makes it possible for the nematode population to grow in favorable conditions.

Half-empty beds – the result of severe infection of the casing layer by nematodes

Half-empty beds – the result of severe infection of the casing layer by nematodes
A poor harvesting technique: that is when mushroom stipes and remains are left on the beds – promotes the development of nematodes, hence they will feed on decaying mushroom tissue.