This work describes the phytotoxic effect of different doses of diazinon and different application times on Agaricus bisporus mycelium, and determines the residue levels in mushrooms from the first three flushes. Mushroom cultivation is a widespread commercial activity throughout the world. The application of insecticide diazinon to the compost or casing layer is a common practice to control two mushroom pests, the phorid Megaselia halterata and the sciarid Lycoriella auripila. Application to the compost does not result in any appreciable fall in yield or quality, and does not delay the harvest time. In contrast, application to the casing led to a slight fall (6.2%) in production and a smaller number of mushrooms although they are larger in size. Residue levels of more than 0.01 ppm are detected in many of the samples analyzed, and raising the question whether the product should continue to be used in mushroom cultivation in the conditions in which it is currently applied.
Keywords: Agaricus bisporus; Chemical control; organophosphates.