Comparison of Planting- and Cultivation-Time Applied Insecticides for Managing Corn Rootworm Larvae in South Dakota, 1995

Abstract

Abstract Cavour and Aurora, South Dakota were chosen as sites for comparing at planting and cultivation time applied insecticides for rootworm control. Individual treatment plots consisted of single 15.2 m long rows which were spaced 96.5 cm apart. The study used a RCB design with 4 replications per location. Granular insecticide formulations were applied with modified Noble metering units mounted on a specially adapted Kinze 4-row corn planter. Metering units were ground-driven, and all units were calibrated on the planter. Banded (B) insecticide treatments were applied in an 18-cm swath over the open seed furrow in front of furrow-closing wheels (T-band), and were incorporated by the wheels and drag chains. In-furrow (F) treatments were placed directly between double-disk furrow openers and into the open seed furrow. Cultivation-time liquid treatments were applied using a CO2-powered backpack canister sprayer system. A 1.8-m boom with 4 nozzles (Teejet 8003 flat fan) spaced 45.7 cm apart was used to deliver 20 gpa. Five roots per replicate were dug for each treatment. Roots were washed, examined for corn rootworm larval feeding damage, and rated in accordance with the Iowa 1 to 6 scale. Percent root protection was calculated: % RP = 100 * (1 – [rating of treatment - l]/rating of untreated control). Root injury ratings were analyzed using SAS’s General Linear Models (GLM) procedure with root rating means were compared by Duncan’s Multiple Range Test.