Greenbug Control in Winter Wheat with Seed Treatments and Granular Insecticides, 1991-1992:

Abstract

Abstract NTN 33989 (imidacloprid) was evaluated for greenbug control in winter wheat planted at the following 3 locations and dates in north central TX: Dallas Co. on 11 Nov, Cooke Co. on 26 Nov and Collin Co. on 15 Nov. Soil types were as follows: Dallas Co., Austin silty clay, pH ,= 7.8; Collin and Cooke Co., Houston black clay, pH = 7.8. Wheat seed treated with NTN 33893 75WS was provided by Gustafson, Inc. Disyston 15G was used as a standard. Both granular insecticides were mixed with the seed and applied in-furrow. All wheat seed used in the trial was from the same lot. Plots measured 6 X 20 ft and were arranged in a RCB design with 4 replications. Plots were planted with a small plot planter at a rate of 80 lb of seed/acre. Seventeen inches of rain fell after planting through February with a total of 40 days of rain. Greenbug infestations did not develop in the test plots because of these rains. Also, greenbug parasites and predators were active throughout the mild winter and further reduced greenbug densities. To assess insecticide activity, a 2 inch diam plug of wheat plants was dug from each of the center 2 drill rows of each plot and potted in a 2.5 X 2.5 inch plastic pot. Pots were infested with greenbugs obtained from a laboratory colony which originated from the test region. Greenbugs were applied with a hand held inoculator calculated to deliver 30 greenbugs per pot. Infested pots were held in an incubator at 70° F for 7-10 d at which time the greenbugs in each pot of wheat were counted. Each test location was sampled once.