Control of Western Corn Rootworm Larvae in West Central Nebraska, 1995

Abstract

Abstract Insecticides were applied to suppress larval rootworm populations in 2 fields near North Platte, NE. Both fields were composed of Cozad silt loam soils. In Field 1 ‘DeKalb 566’ hybrid field corn was ridge-planted with a John Deere 7100 Max-emerge planter, to a non-tilled seed bed on 19 May. At the time of planting, soil moisture was adequate for germination and the soil temperature at a depth of 5 cm was about 8° C. Several insecticides were applied at planting to plots 2 rows wide, 10 m in length, with a bicycle wheel type applicator. Four replications of each treatment were arranged in a RCB design. T-band applications were made by applying a 7 inch band of insecticide to an open seed furrow. In-furrow applications were made by applying insecticide directly into the seed furrow. After the insecticides were applied, furrows were closed with a rotary hoe and insecticides were incorporated with a rake. Field 2 was ridge-planted to ‘BoJac 577’ field corn with a John Deere 7100 Max-emerge planter, in a non-tilled seed bed on 18 May. At the time of planting, soil moisture was adequate for germination and the soil temperature at a depth of 5 cm was about 13° C. With the exception of 4 field length strips, 12 rows in width, Lorsban 15G was applied at planting with insecticide boxes on the planter at a rate of 1100 g Al/ha. Granular and liquid insecticides were applied to untreated strips in Field 2 immediately prior to cultivation on 22 Jun. The corn plants were in the early whorl stage (V3 stage) of development at the time of application. The plots for the granular treatments in Field 2 were 10 m in length and 4 rows wide. The granular treatments were applied in a 7 inch band, over the whorl of the plants, with a bicycle wheel type applicator. Furadan 4F was applied to 10 X 4 m plots in Field 2, either broadcast over the top of the plants or in 7 inch bands to the base of the plants. All liquid treatments were applied in a total volume of 120 liters/ha at 30 psi. All treatments were replicated 4 times and arranged in a RCB design. Treatments in both fields were evaluated 26 Jul by rating washed roots, using the 1-6 Iowa root damage rating scale, of 4 plants from each replicate.