Insecticides Applied to the Soil for Control of the Colorado Potato Beetle in Virginia12

Field experiments to control Leptinotarsa decemlineata (Say) were conducted on Irish potatoes in southeastern Virginia from 1967 through 1971. Fourteen different compounds in several formulations and rates and methods of application were evaluated as soil insecticides. Based on overall performance, aldicarb granules banded alongside Irish potato seed-pieces at planting at 2 lb AI/acre gave best results and provided almost complete potato beetle protection from plant emergence to harvest. Carbofuran (2 lb AI/acre) was almost as effective as aldicarb, but the plants suffered some late season adult-feeding damage. Phorate, Dasanit® (O, O-diethyl O-[p-(methylsulfinyl)phenyl] phosphorothioate), and disulfoton gave highly significant control, but they generally produced lower yields and specific gravities than aldicarb or carbofuran. Drip banding concentrates of phorate, disulfoton, and Dasanit generally gave poorer results than granular formulations. Liquid insecticide-liquid fertilizer combinations of phorate or carbofuran were as effective as comparable rates of the granular insecticides.