Evaluation of Corn Rootworm Insecticide Treatments and Carry-Over Control of European Corn Borers in South Dakota, 1995

Abstract

Abstract A secondary benefit of corn rootworm insecticide treatments could be the residual control of European corn borer (ECB) larvae. Our study was repeated at sites near Aurora, Cavour, Delmont, and Garretson, South Dakota to assess the efficacy and secondary ECB control provided by 3 insecticides (Furadan, 60720A, & Regent). Treatment plots consisted of single 15.2 m long rows which were spaced 96.5 cm apart. The study was arranged in a RCBD with 4 replicates at each site. Granular insecticide formulations were applied with modified Noble metering units mounted on a specially adapted Kinze 4-row com planter. Metering units were ground-driven, and all units were calibrated on the planter before applications. 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 liquids were applied using a CO2-powered backpack canister sprayer system equipped with a single nozzle (Teejet 8003 flat fan) hand-held boom. The system was calibrated to deliver 20 gpa. To evaluate rootworm damage 5 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. For assessment of ECB control, 10 com stalks were randomly chosen from each plot. Plants were split vertically and examined for corn borer tunneling damage. The number and length of ECB cavities were analyzed along with root injury data using SAS’s General Linear Models (GLM) procedure and means were compared by DMRT.