Organophosphorous and carbamate insecticides as soil treatments for the control of wireworms

SUMMARY Laboratory methods are described for testing soil insecticides against wireworms, and the results obtained with some organophosphorus and carbamate compounds tried as possible alternatives to chlorinated hydrocarbons are reported. The most promising compounds in the laboratory tests were thionazin, O-ethyl S-p-tolylethylphosphonodithioate (Bayer 38156) and fenthion. These were tested in a small-plot field trial with cereals, on land severely infested with wireworms: the compounds were applied to the soil as sprays at 2·7 lb./acre active ingredient before the crop was drilled. Fenthion was ineffective, but thionazin and Bayer 38156 each increased yields significantly and the increases were associated with diminished wireworm populations.