Insecticidal Corn Rootworm Control Using Various Application Rates and Techniques, 1991

Abstract

Abstract Three studies were conducted at sites in Brookings, Garretson, and Nunda, SD. Treatments consisted of varied rates and application techniques (band and in-furrow) of registered and experimental insecticides for control of corn rootworm larvae. Design for all studies was a randomized complete block with 4 replications. Individual treatment plots consisted of single 15.25 m long rows spaced 96.5 cm apart. Insecticide granules were applied with modified, ground-driven Noble metering units mounted on a specially-adapted Kinze 4-row corn planter. Metering units were calibrated on the planter prior to insecticide applications. Banded treatments were applied in an 18 cm swath in front of the furrow-closing wheels, and incorporated by the wheels and drag chains. In-furrow applications consisted of insecticide granules directed immediately between the double disk furrow openers. Corn was seeded at 23,000 kernels per acre at all sites. Five roots per replicate were dug for each treatment. Roots were washed, examined for feeding damage, and rated in accordance to the Iowa 1 to 6 scale. Corn rootworm infestations were low to moderate, which was consistent with very few grower reports of significant rootworm damage. Above normal spring rainfalls were experienced, although no plots were lost due to flooding. However, the abundance of postapplication precipitation may have affected efficacy associated with application technique.