Toxicity of pesticides and herbicides used on cotton plants to the entomopathogenic fungus Nomuraea rileyi

Abstract

The effects of pesticides (seven insecticides and four herbicides) normally used for cotton (Gossypium hirsutum L.) pest control were tested in vitro on the development of the entomopathogenic fungus Nomuraea rileyi (Farlow) Samson, at the concentrations of 10 ppm, 100 ppm and 1.000 ppm. The growth of N. rileyi was inhibited by the insecticides malathion; monocrotophos and methyl parathion at all concentrations tested. The insecticides deltamethrin, permethrin, phenovalerate and the herbicides alachior, diuron, pendimethalin and trifluralin were inocuous to the fungus. No injurious effect was observed concerning the dimethoate at the recommended doses of 250 to 300 ppm/ha; inhibition was observed at the dose of 1.000 ppm/ha.