Control of Potato Aphids With Systemic Insecticides1

Abstract

Field tests of systemic insecticide treatments on potatoes at planting were evaluated for their effect on emergence, yield, and the control of Myzus persicae (Sulzer), Macrosiphum euphorbiae (Thomas), Aphis nasturtii Kaltenbach and Aulacorthum solani (Kaltenbach). Seed dips or carbon formulations of Di-syston® (O, O-diethyl S-[2-(ethylthio)ethyl] phosphorodithioate) or phorate delayed emergence but granular formulations of these materials did not. Dipping seed pieces before planting in a 0.5% Di-syston solution gave good control of aphids but reduced yield by almost 45%. Granular Di-system at 2 pounds active ingredient per acre gave effective control of aphids and was the only treatment consistently to produce more Grade A potatoes than the check throughout the season. A single treatment of the soil at planting time with schradan or demeton (2 pounds active per acre) gave as good or better control of aphids than either malathion or DDT sprayed on the plots such week for 9 weeks. Analysis of the tubers in late September showed that the residues from these systemic treatments did not exceed 0.03 p.p.m. in 1960 and 0.06 p.p.m. in 1961. Plants grown from daughter tubers 9 and 10 weeks after storage were not toxic to aphids.