Evaluation of Insecticides To Control Larvae of The Corn Rootworm in Nebraska, 1976

Soil insecticides to control larvae of the corn rootworm were evaluated at five locations in Nebraska in 1976. Corn plots were planted May 6, May 4, May 11, May 12, and May 14 at Mead, Clay Center, North Platte, Scottsbluff, and Concord, Nebraska respectively. With the exception of the Concord test, all experiments were conducted on irrigated land. Each insecticide was applied in a seven inch band over the row (1.2 oz a.i./lOOO ft of row) at planting time and incorporated by a press wheel. Each treatment consisted of one row, 50 ft long. All experiments were arranged in randomized complete block designs with four replications/treatment. Treatments were evaluated for root damage in mid- July by digging five equally spaced plants from each row and rating the roots for rootworm feeding damage using a 1-6 damage scale (1 = minor damage; 6 = three or more root nodes destroyed). Yield was obtained by harvesting the middle 40 ft of each row and converting to bu of no. two corn/acre.