Abstract
Various pesticides were applied to blister stage (R6 stage) hybrid field corn on 10 Aug, near North Platte, in west central NE. The treatments were applied with a CO2 charged backpack sprayer through 8001 flat fan nozzles at 206,786 Pa (30 psi), in a total volume of 196.4 liter/ha (21 gal/ acre). Each treatment was applied to 3 × 10 m plots, replicated 4 times in a RCBD. Five days before the pesticide application Banks grass mites were applied to 2 plants in the center of each plot by attaching 2 well-infested leaves with strapping tape. Four days following application the number of rootworm beetles and predatory insects were evaluated by counting all beetles on four randomly selected plants in the middle of each plot. For each artificially infested plant size of mite colonies was rated on the underside of 3 leaves below the ear, the ear leaf and 2 leaves above the ear at 9, 17, 27 and 46 DAT. Ratings were made on a 0-6 scale where 0 = no mites, 1 = individual mites, 2 = small colonies, 3 = large, individual colonies, 4 = large connected colonies but not completely covering the underside of the leaf, 6 = leaf dead due to spider mite damage. In addition to evaluation of spider mite colonies, arthropod predators were also counted.