This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Mushrooms are subject to several diseases, one of the worst being caused by a fungus known as Hypomyces pemiciosus. This parasite spreads quickly, and distorts the Mushrooms into soft irregular masses of putrid tissue in time. There is practically no remedy, and so prevention should be aimed at rather than cure. Any Mushroom infected with disease of any sort should at once be removed from the house and burnt. Every precaution should be taken to prevent disease occurring. A concrete or clinker bottom should be provided for the manure to be unloaded on as it is brought in, and this should be drenched two or three times a year with a solution of clubicide or similar fungicide 1 to 1000. All spent manure should be carted as far, and as soon, as possible from the houses, and soil that has had spent manure mixed with it should never be used for casing without first being sterilized, either by using the waste heat from the boiler, or treating by steam. Sterilizing by steam has been found to have a marked result on the weight and quality of the crop, and growers may be confidently recommended to give it a trial. Old Cucumber soil answers excellently for casing after being sterilized.
Another pest is the maggot of the Mushroom Fly, a pellucid greenish-white grub from 1/8 to 1/2 in. long when fully grown. Several of these maggots bore their way from the base of the stalk right through to the cap, and thus destroy the Mushroom. So far no remedy has been devised beyond picking out and burning the injured Mushrooms. The pest no doubt comes in the manure, where the parent has laid the eggs, and these hatch out in the genial warmth of the bed. It may be possible to check the ravages of this maggot by spraying the prepared manure with soft-soap-and-quassia-chip solution a few days before making up into beds.
In conclusion, it should be thoroughly realized by the prospective Mushroom grower that vigilant superintendence by the employer or responsible foreman is at all times necessary. Without it, Mushroom growing is practically doomed to failure. [p. A. c]