Comparison of Four Methods of Applying Insecticides for Control of Wireworms on Potatoes12

Abstract

Preplant broadcast, at-plant sidedress, seed-piece furrow, and postemergence sidedress were tested as methods of applying insecticides for control of the Pacific Coast wireworm, Limonius canus LeConte, the sugarbeet wireworm, L. californicus (Mannerheim), and the Great Basin wireworm, Ctenicera pruinina (Horn), on potatoes. Differences in control were found for the various insecticides applied by the four methods at the three locations. Also, chemicals applied by a given method differed, depending on location. In general, all chemicals were as effective as fonofos, which was used as a standard, at all three locations, except carbofuran, chlorpyrifos G, and fensulfothion G. Carbofuran was tested at rates higher than those of fonofos, and chlorpyrifos G was tested at rates comparable to those of fonofos. Fensulfothion G, also used at rates higher than those of fonofos, gave control comparable to fonofos against a high density of wireworms, but less control against a low density. Comparison of the application methods with the standard showed that all four were equally effective against a low density of wireworms; however, against higher densities, at-plant sidedress was inferior to the other three methods, which were equally effective.