Field Tests with New Insecticides for Control of the Southern Corn Rootworm Attacking Peanuts in Virginia1

Abstract

A series of small-plot experiments was used to evaluate 31 band treatments of 13 candidate insecticides against aldrin- and heptachlor-resistant populations of the southern corn root worm, Diabrotica undecimpunctata howardi Barber, in Nansemond County, Virginia. Previously weighed quantities of granule and dust treatments were applied by hand in 18- to 20-inch bands over the row, and immediately raked into the soil. Spray treatments were applied with a compressed-air, knapsack sprayer. Effectiveness of the treatments was determined by comparing the percentage of penetrated nuts from four plants selected at random from each plot. The results showed that soil treatments with either aldrin or heptachlor, at a rate of 2 pounds of actual toxicant per acre, are no longer effective in controlling this pest on peanuts in Viriginia. Of the chemicals tested, diazinon, Zinophos® ( O, O -diethyl O- 2-pyrazinyl phosphorothioate), and General Chemical Compound 4072 (2-chloro-1-(2,4-dichlorophenyl)vinyl diethyl phosphate) were most effective. Yield and crop value data secured with diazinon and Zinophos, at dosages of 2.44 and 2.52 pounds per acre, respectively, both showed a nut yield increase of more than 71% and a nut value per acre increase of more than 86%, as compared with the untreated check.