Toxicity of soil-applied fungicides and gypsum to the vesicular–arbuscular mycorrhizal fungus Glomus mosseae in groundnut

The effects of four commonly used commercial formulations of contact fungicides (pentachloronitrobenzene, captan, captafol, and mancozeb) and gypsum on the vesicular–arbuscular mycorrhizal development of Glomus mosseae (Nic. & Gerd.) Gerd. & Trappe in groundnut were studied. Drenching the soil with pentachloronitrobenzene or gypsum at the time of seed sowing significantly inhibited the colonization and sporulation by the fungus; the other fungicides were less toxic. Captan, a widely used fungicide, was least inhibitory on development of the fungus. Pentachloronitrobenzene, gypsum, and captafol treatments significantly reduced the plant biomass.