The cheapest disease control on a mushroom farm happens when the crop is over. NHB describes a cook out at the end of the crop, holding compost at 70 °C for 12 hours to kill pathogen mycelium and spores, and notes that 70 °C for 2 to 3 hours kills all stages of pests and pathogens.
Spent compost still breeds flies. NHB advises a compost pit covered with at least 10 cm of manure, and doors and ventilators screened with nylon net of 35 mesh or finer. A 15 watt yellow light trap helps you monitor what is flying.