Degradation of pesticides during mushroom compost preparation and production

Wash down water containing pesticides is recycled in preparation of commercial mushroom compost. This research determined the degradation of endosulfan, diazinon, dimethoate, malathion, permethrin, captan, chlorothalonil and propiconazole in water and compost, and the accumulation of residues in mushroom tissues.; An increase in pH and temperature augmented the hydrolysis of most pesticides; whereas, diazinon underwent acidic hydrolysis and propiconazole hydrolysis was independent of temperature. Microbial degradation was the major pathway for diazinon but a secondary pathway for malathion, dimethoate, chlorothalonil, and the two isomers of endosulfan. The composting process significantly degraded most pesticides. Both propiconazole and permethrin were relatively persistent in both water and compost. Neither pesticide residues accumulated in mushrooms nor mushroom yield affected if the mycelial growth was normal. The recycled water, mushroom compost preparation and production are adequate in reducing most pesticides. Persistence of propiconazole and permethrin could cause concern for leachate from the spent substrate.