Corn Rootworm Insecticide Screening, 1994

Abstract

Abstract Test plots were planted on 4 May. Banded (7 inch) and in-furrow planting time treatments were applied with a cone-belt distributer mounted on a John Deere Maxemerge equipped with incorporation tines. Cultivation treatments were applied over the row on 3 Jun with the cone-belt distributer mounted on a hand-powered bicycle wheel applicator. Cultivation application was followed immediately by a tractor mounted cultivator after all treatments were applied. The seeding rate was 18,000 seeds/acre on 30 inch rows. Soil type was silty clay loam (OM > 3%, pH 6.5). Previous crop was late planted corn planted as a trap crop. The field was double disked prior to planting. Preplant anhydrous ammonia was applied at the rate of 90 lb per acre prior to planting. Approximately 20% corn stalk residue was remaining after field preparation. The experimental design was a RCB with 4 replications, each treatment a single row 50 ft long. Five randomly selected roots from each plot (20/treatment) were rated on the Iowa State 1—6 scale (1, no damage; 6, 3 or more nodes pruned to within IVi inch of the stalk). Twenty roots were rated for each treatment. The roots were dug and rated on 11 Jul. Soil moisture was adequate at planting time and rainfall prior to rating was near normal.