Variation in Sensitivity of Mushroom Strains to Diazinon Compost Treatment

Abstract

Incorporating diazinon into the compost media in which mushrooms are grown is widely practiced to control three dipteran pests, namely, Lycoriella mali (Fitch) and L. multiseta (Felt) (Sciaridae) and Megaselia halterata (Wood) (Phoridae). However, there were indications at times that diazinon-treated compost had lower yields than untreated compost. To determine if the lowered yields were due to differences in sensitivity to diazinon of the different strains, eight commonly used strains were grown in treated and in untreated compost, and the yields were compared. Four strains had significantly lower weights when treated with diazinon, and three of these had significantly fewer mushrooms. The weight of the most sensitive strain was reduced by 30% and the number by 26%. The treatment also delayed the appearance of the growth flushes in sensitive strains. Poor cultural practices tended to result in increased phytotoxicity. There was no difference among the strains in the quantity of diazinon translocated from the compost to the fruiting bodies. The maximum recorded was 0.027 ppm, and most samples contained less than 0.01 ppm.