Effect of Systemic Insecticides on Green Peach Aphid Populations on Potatoes1

Abstract

Under conditions of continuous reinfestation of potatoes by winged aphids, multiple applications of parathion sprays were as effective as schradan or demeton in reducing populations of wingless aphids the 1st week after application. Parathion and Isolan had little residual effectiveness, whereas schradan at 16 oz. per acre remained moderately effective for 2 weeks and schradan at 32 and demeton at 12 oz. for 3 weeks. Leaf roll virus disease spread occurred in all treatments in amounts only slightly below that in the untreated check. Residues up to 0.38 ppm demeton and 0.59 ppm schradan were found in the potato tubers at harvest time. However, these residues did not adversely affect rats and monkeys fed on the potatoes.