Preliminary Study on Some of the Factors Affecting Control of Western Corn Rootworm Larvae with Soil Insecticides1

Abstract

In 1966, a study of the effect of date of corn planting and time of insecticidal treatment on the performance of some of the soil insecticides for control of larvae of western corn rootworm, Diabrotica virgifera LeConte, was initiated. Corn was planted on 3 dates and treated at 2 different times with 4 organic phosphate insecticides (phorate, diazinon, disulfoton, and a stabilized parathion). When corn was planted April 30, phorate applied at planting controlled the western corn rootworm larvae better than the other tested insecticides, but for corn planted on May 20 phorate applied as either a planting or basal treatment performed significantly better. However, for the June 4 planting date all insecticides were equally effective. An analysis-of-variance table and graph of these data are presented.