Control of Cotton Aphid, 1989

Abstract

Abstract Five chemical treatments and an untreated control were compared in 6 row by 1,254-ft plots of cotton grown on 38-inch rows on a commercial farm located near Robstown, TX. All treatments were applied on 4 May and were replicated 3 times in a randomized complete block design. Tractor mounted spray equipment was calibrated to deliver a total spray volume of 10 gal/acre through 2, size 8002 nozzle tips/row at 38 psi. Flat fan spray tips were used due to the wind speed (15-28 mph) and the small size of plants (pinhead square stage). However, wind was blowing exactly parallel with the treatd rows, thus drift between plots was minimal. Insecticide efficacy was measured by (1) counting the no. of aphids on 20 randomly chosen individual plant “key leaves” from the center 2 rows of each plot (the “key leaf was the third leaf down the main stem from the terminal; usually it is the highest fully expanded leaf on the plant), (2) hand harvest of 13.75 row-ft subplots on 10 and 18 Jul at 3 sites from the center 2 rows of each plot, and (3) evaluation of cotton fiber properties. Harvested seed cotton was ginned on a 10-saw Eagle laboratory machine. Lint samples were sent to the International Center for Textile Research and Development, Lubbock, TX for fiber analysis on a High Volume Instrument Tester manufactured by Motion Control.