Evaluation of Insecticides for Control of Aphids on Nucotn 33B Cotton, 1997

Insecticides were evaluated at North Mississippi Research and Extension Center, Verona, MS, in a RCB design with 4 replications. Plot size as 4 rows wide (38-inch row spacing) by 50 ft long with 4 untreated rows between plots and a 10-ft planted buffer at the end of each plot. Insecticides were applied on 11 Jul with a high-clearance spray tractor equipped with two Spraying Systems TX4 hollow-cone nozzles per row and calibrated to deliver 10 gpa at 40 psi at 3 mph. Carrier of the in-secticide was water. Samples were taken from 10 leaves per plot at each of two levels on the plant: upper (first fully expanded leaf), and mid (mainstem leaf located one-third down the plant), aphids were counted on the underside of each leaf. Yield (lb of seed cotton per acre) was determined by mechani-cally harvesting the center two rows of each plot, and measuring the actual area picked.