Cotton Aphid Control in the Macon Ridge Region of Louisiana, 1991

Two tests were conducted to evaluate the efficacy of selected insecticides against cotton aphids in non-irrigated cotton planted 17 Apr. For both tests, plots consisted of 4 rows (102 cm centers) x 15 m. Treatments were arranged in a randomized complete block design with 4 replications. The test field had been treated previously with Ammo 2.5 EC (0.033 kg [AI]/ha) to stimulate cotton aphid infestations. Insecticides were applied to Test 1 and Test 2 and 18 Jul with a tractor mounted boom equipped with a compressed air system calibrated to deliver 93.6 liters total spray/ha through Teejet X-12 hollow cone nozzles (2/row) at 3.02 kg/cm2. Plots were sampled on 22 (4 DAT) and 25 Jul (7 DAT). Treatment efficacy was evaluated by sampling the plant terminal (all apical shoot growth above and including the first fully expanded leaf). Fifteen and 10 samples on 4 DAT and 7 DAT, respectively, were collected from each plot and held in glass jars. Aphids were washed from the plant foliage onto 300 mesh wire sieves, backwashed onto ruled filter paper (7 cm) and counted using a binocular dissecting scope. These tests received 0.9 cm rainfall on 18 Jul and 1.8 cm rainfall on 19 Jul.