It is impossible to over emphasize the importance and benefits of strict adherence to tidiness and sanitation of the work area and continued attention to the cleanliness of the growing areas. Peak heating of the compost will eliminate most fungal problems and insure that you start your cultivation with a medium free of insects. The addition of 1 lb. of copper sulfate per ton of compost will help prevent those diseases not killed by peak heating. Zineb is a selective fungicide that is often used. Bacterial problems are generally a result of the combination of too high a humidity with a lack of adequate ventilation.
Insect pests can be a constant source of irritation.
Everything within ones' power should be done to prevent insects' access to growing rooms. Diazon can be used as a dust on casing for mites and flies. Malathion can also be used but tends to cause pinhead abortion when sprayed. The use of diatomaceous earth in the casing layer can be attempted as a preventative approach to larva infestation. The immediate removal of contaminated boxes is highly recommended.