Mites

Many mites are commonly found in straw and manure, most species are beneficial to mushroom growing as they feed on eelworms and other mites, although some can cause damage, these are as follows:-

1.Tarsonemid mite (Tarsonemus myceliophagus)

2.Tyroglyphid mites (Tyrophagus spp)

3.Red Pepper mites (Pygmephorus spp)

These mites are pale brown and are so minute that they are only visible with the aid of a microscope. They cause damage by feeding entirely on hyphae of mushrooms and the grower will know if he has these mites present, as the base of the stem of the mushroom will show a reddish brown discolouration. Where severe infestations occur the whole base of the mushroom may be detached from the growing surface.

1. As with eelworms little can be done when mites are present in the growing house, therefore efficient composting and peak heating must take place to ensure that they are killed during the pasteurisation process.

2. Good hygiene should be practised around the farm, especially in the clearance of crop debris.

(Tyrophagus spp)

These mites can be identified as they are slow moving, translucent, with long hairs on their bodies.

If these mites are present in abundance they eat small pits in the caps and stalks. These pits then suffer from bacterial decomposition, which breaks down tissues just below the surface. This results in the skin collapsing which leaves an open pit. Tyroglyphids may also feed on mushroom mycelium, where they are present in large numbers, crop reductions can be caused.

Mites usually gain entry into the compost by clinging onto Sciarid flies when the mites are the migratory stage. These migratory stages are normally produced when mites become overcrowded.

The mites should not be a problem where efficient composting and peak heating takes place. Organic debris should not be allowed to accumulate around the farm as it provides a breeding ground for mites.

(Pygmephorous spp)

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.

The mites are yellowish-brown in colour, 0.25 mm in length and have a flattened appearance, they also are capable of rapid rates of reproduction.

As already stated these mites are secondary pets and they often swarm on the casing and mushroom surfaces. Where this happens their presence makes the mushrooms unsaleable. These mites can also spread spores of Trichoderma from bag to bag.

1. Efficient composting and peak heating.

2. Good husbandry around the farm.

3. Where mites appear on individual bags during cropping, these should be sealed up and disposed of.