Corn Rootworm Insecticide Screening, 1996

Abstract

Abstract The test plots were planted on 6 May. 7-inch banded (TB) and in-furrow (IF) treatments were applied at regular labeled and reduced (R) rates. Most treatments were applied with a cone-belt distributor mounted on a John Deere Maxe-merge equipped with incorporation tines. Regent 80 WP was applied in the seed furrow in front of the press wheel with a backpack sprayer equipped with a hand held nozzle calibrated to deliver 1.0 gpa finished spray. Smartbox (SB) planting time treatments were applied separately with the Smartbox mounted on the tractor. Cultivation treatments (C) were applied over the row on 11 Jun with the cone-belt distributor mounted on a hand-powered bicycle wheel applicator. The entire plot was cultivated immediately after application of the 11 Jun treatments by a tractor mounted cultivator. The seeding rate was 20,300 seeds/acre on 30 inch rows. Soil type was silt loam (OM > 3%, pH 6.5). Previous crop was late planted corn planted as a trap crop. The field was disked twice prior to planting. Approximately 20% corn stalk residue was remaining after field preparation. The experimental design was a RCB with four replications, each treatment being a single, 45 ft long row. Five randomly selected roots from each replication were rated on the Iowa State 1-6 scale (1, no damage; 6, 3 or more nodes pruned to within VA inch of the stalk). The roots were dug and rated on 23 and 25 Jul. Topsoil and subsoil moisture was at field capacity at planting time.