Efficacy of Insecticides Applied to Twospotted Spider Mites on Field Corn in West Central Nebraska, 1987

Abstract

Abstract Cygon 400, Capture 2 EC, and Comite were aerially applied in one trial 16 Aug to dough-stage field corn. Capture 2 EC was applied through a center pivot irrigation system; Counter 15 G and Parathion 8 EC were aerially applied 19 Aug to field corn in a second trial. Plots to be aerially applied were 120 ft wide by field length. Chemigation treatments were applied to 8 acre triangular-shaped plots. All treatments were replicated twice in a randomized complete block design. Sizes of naturally-occurring twospotted spider mite colonies were rated on the under surface of 7 leaves starting with 3 leaves below the ear through 3 leaves above the ear. Ratings were made with a 0-6 scale where 0 equaled no mites on the leaf, 1 equaled individual mites present, 2 equaled well-formed colonies ... up to 6 where mite colonies were so large that the under side of the leaf was completely covered and the leaf had died due to mite feeding. Mites were evaluated on 4 plants located about 250 ft from the edge and in the center of each plot. Evaluations were made 1 d prior to application, 12 and 21 d post-application in the first trial; 7 and 14 d post-application in the second trial.