Chemical Control of Wireworms on Potatoes12

Abstract

In 2 of 3 tests conducted to evaluate chemicals for control of the Pacific Coast wireworm, Limonius canus LeConte, and the Great Basin wireworm, Ctenicera pruinina (Horn), broadcast applications resulted in lower percentages of injured and culled tubers than did sidedress applications. In the 3rd test, there were no differences between broadcast, furrow, and at plant sidedress applications. Individual compounds differed in effectiveness depending on method of application in all 3 tests. Compounds that were very effective included N-2596 (S-(p-chlorophenyl)O-ethyl ethylphosphonodithioate), CGA 12223 (0-[5-chloro-1-(1-methylethyl)-lH-1,2,4-triazol-3-yl] O,O-diethyl phosphorothioate), and ethoprop. All 3 were as effective as fonofos (used as a standard) in reducing injury to tubers. Wireworm infestations (presence of wireworms or feeding on seed pieces and tubers) increased from time of planting until 16 wk; however, the highest number of wireworms per hill was found at 6 wk, but decreased thereafter. No difference in tuber injury was noted between 15–16 wk after planting and at harvest (20–21 wk).