Corn Rootworm Larval Control in South Dakota, 1989

Abstract Three granular corn rootworm insecticide studies were conducted to evaluate various application techniques, rates, and formulations. Garretson, Nunda, Rutland, and 2 Lake Andes sites served as locations for these studies. The experimental design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single rows, 15 m in length, with 96.5 cm row spacing. Granular formulations of insecticides were applied with modified Noble metering units mounted on a specially-adapted Kinze, 4-row corn planter. The metering units were ground-driven, and all units were calibrated on the planter. Insecticide granules were applied in a 7-inch band in front of the furrow-closing wheels and incorporated by the wheels and drag chains. Furrow applications were directed immediately between the double disk furrow openers. Wilson brand 1100 was the corn variety utilized, and it was seeded at a rate of 22,100 kernels/acre at all study locations. Five roots/replication were dug from each treatment. Roots were washed, examined for rootworm feeding damage, and rated in accordance to the Iowa 1 to 6 scale. Sufficient levels of soil moisture were present at all locations. Rootworm infestations ranged from moderate to heavy which resulted in untreated plots being severely damaged. Significant treatment separations were observed in all studies among various pesticides.