Evaluation of At-Planting and Foliar Insecticide Applications for Control of Early-Season Pests in Cotton, 1987

Abstract

Abstract A small-plot field study was conducted at the Texas A&M Univeristy Research and Extension Center at Corpus Christi to evaluate soil and foliar insecticides for control of early-season pests in dryland cotton. Four treatments and an untreated check were compared in 4-row × 30-ft plots of cotton planted 19 Mar on 38-inch rows. Treatments were replicated 3 times in a randomized complete block design. Using Gandy applicator boxes, soil insecticides (Counter and Temik) were applied in the seed furrow at planting time. Applications of the foliar insecticide treatment (Cygon) were initiated at the pinhead square stage of cotton growth on 8 May; subsequent applications were made on 14, 21, and 28 May. Cygon applications were made with a CO2-pressurized (35 psi) backpack sprayer, calibrated to deliver 4.5 gal total spray/acre through 2 size 3X hollow-cone nozzles/row. Edaphic conditions at planting time consisted of 15% water (by weight) in top 4 inches of soil and a temperature of 67°F at 4 inches below surface of soil. The soil type was Victoria clay with an organic matter content of 1.7%. Following planting, rainfall did not occur at the test site until 4 Apr (1.0 inch). Accumulated rainfall at the test site from planting date to first bloom stage of cotton growth (the period during which data on pest infestations were gathered) was 5.8 inches. A light freeze (31°F for 1 hr) occurred 31 Mar. Also, the test site was subjected to heavy rainfall (12 inches) and flooding during the first 2 wk in June; fruit-shed by plants during this period was extensive. Efficacy of treatments was evaluated by inspecting terminals of 20 randomly chosen plants in each plot for numers of fleahopper nymphs and thrips and by inspecting terminal leaves (third leaf from apex of plant) of 20 randomly chosen plants in each plot for numbers of aphids and adult female mites. A plant count was taken at the third leaf stage of cotton growth to determine whether the soil insecticides had an effect on the development of a stand. Seed cotton was hand-harvested from 13.6-ft section of row in each plot for yield analysis.