Corn Rootworm Control, 1988

Nine soil insecticides were applied at the full rate at planting time and at a reduced rate at planting and first cultivation times at Concord, Nebr. The test plots were planted 6 May in a continuous corn field (at least 8 yr) with a silty clay loam soil type. The experimental design was a randomized complete block with 4 replicates. Each treatment consisted of a single 50-ft-long row; rows were 30 inches apart. Insecticides were applied in a 7-inch band by a Noble granular metering unit mounted on a hand-powered bicycle applicator equipped with incorporation tines. Cultivation time treatments were applied over the row followed immediately by a tractor-mounted cultivator. Planting time treatments were applied on 10 May and cultivation treatments were applied on 31 May. No phytotoxicity was observed. Feeding damage was evaluated 7-12 Jul. Five roots were dug from each treatment row and rated by the Iowa 1-6 scale (1, no damage; 6, 3 or more nodes of roots completely destroyed).