Efficacy of Selected Insecticides Against Cotton Aphid on Cotton, 1997B

Two tests were conducted to evaluate the efficacy of selected insecticides against cotton aphids in non-irrigated cotton at the Macon Ridge Location of the Northeast Research Station near Winnsboro, LA. Test 1 was planted 1 May and Test 2 was planted on 5 May. Plots consisted of 4 rows (40-inch centers) X 50 ft. Treatments were arranged in a RCB design with 4 replications. No foliar insecticides were applied to the plots before the test was initiated. Prior to treatment, cotton plants with infestations of cotton aphids in the plant terminals (20/plot) were identified with plastic bags. Treatments were applied on 25 Jun and 1 Jul to Test 1 and Test 2, respectively. In both tests, insecticides were applied with a handboom and CO2-charged system calibrated to deliver 10 gpa through Teejet 8002 flat-fan nozzles (2/row) at 28 psi. Treatment efficacy was evaluated by sampling 10 tagged plant terminals (all apical shoot growth above and including the first fully expanded leaf) from each plot at 3, 6, and 11 DAT. Treatment efficacy was evaluated by sampling ten plant terminals (all apical shoot growth above and including the first fully expanded leaf) from each plot. Treatments were evaluated in Test 1 on 27 Jun (2 DAT) and 1 Jul (6 DAT) and in Test 2 on 3 Jul (2 DAT) and 7 Jul (6 DAT). Cotton 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 plots received 0.11 and 1.98 inches rainfall on 28 Jun and 6 Jul, respectively. Data were analyzed with ANOVA and means were separated according to DMRT.