Evaluation of Substitutes for DDT in Field Experiments for Control of the Bollworm and the Boll Weevil in Cotton: 1967-691234

Replicated field experiments of certain materials with and without DDT showed that methyl parathion, methyl parathion + DDT, toxaphene + methyl parathion, toxaphene + DDT, and azinphosmethyl + methyl parathion gave good control of the bollowrm, Heliothis zea (Boddie), and the boll weevil, Anthonomus grandis Boheman, when weather was favorable and insecticide applications were made at short intervals. However, when rainfall was excessive and applications could not be applied at short internals, methyl parathion, EPN (O-ethyl O-p- nitro-phenyl phenylphosphonothioate), EPN + methyl parathion, and toxaphene + methyl parathion at the rates tested failed to give good control. In 2 experiments in which the differences in yield were statistically significant, formulations containing toxaphene + DDT + methyl parathion and toxaphene + DDT produced the highest yields, indicating that under prevailing weather conditions and bollworm population pressures in the southeast, use of materials with less residual activity will result in poorer control and lower yield.