Studies on the chemical control of wireworms (Agriotes spp.) III.—The direct and residual effects of BHC, aldrin and dieldrin

An experiment on Geescroft field, Rothamsted, from 1951 to 1954, tested the direct and residual effects of BHC, DDT, aldrin and chlordane applied to control wireworms (Agriotes spp.) in wheat.The treatments applied were BHC seed dressing at 2 oz./bushel of a dressing containing 20 per cent. γ isomer of BHC; BHC 3·5 per cent. dust, combine-drilled to give 3·8–4·0 oz. γ isomer per acre; DDT 5 per cent. dust, combine-drilled to give 7·5 lb./acre technical DDT; aldrin 1·78 per cent. dust, combine-drilled to give 3·56 lb./acre technical aldrin, and chlordane 5 per cent. dust, combine-drilled to give 5 lb./acre chlordane.In the year of application, the first out of old grass, when wireworm attack was slight, the plots treated with BHC, aldrin and chlordane, combine-drilled, gave significantly greater yields than the control plots. In the following year, when wireworm attack was heavier, residual effects on yield were observed on plots initially treated with BHC, DDT, aldrin and chlordane, combine-drilled. In the third year, residual effects on yield were observed on the plots initially treated with BHC, aldrin and chlordane, combine-drilled.No direct or residual effect of BHC seed dressing was observed.The residual effects are closely associated with the effect of the treatments on the wireworm population.The results are compared with those of previous experiments and the increases in yield from the various treatments are discussed briefly.