Delta Aphid Test-III, 1988

Nineteen treatments were evaluated for relative efficacy against aphids on irrigated cotton planted 11-12 May on the Avery farm near Shaw, MS. Plots were 8 rows by 50 ft and were arranged in a randomized complete block design with 4 replications. Treatments were applied 1 Aug to the 4 inner rows of each plot by high clearance spray tractor equipped with a compressed air-plot spray system with 2 TX-4 nozzles/row calibrated for 5 gal/acre. Prior to this test 8 applications of insecticide had already been applied to the field as follows (rates are lb [AI]/acre); 3 applications of Orthene 75 S at 0.25; Swat 8 E at 0.15; Bidrin 8 E at 0.2; Swat 8 E at 0.25; Azodrin 5 E at 1.0. Prior to treatment, the mean number and standard error of aphids on Vb of each of 10 leaves from each of 20 plots (5 random plots/rep) from the upper third of the canopy was 469.8 and 237.1, respectively. Although the standard error was high, the minimum number of aphids/plot was greater than 40.2 aphids/leaf. Posttreatment data were collected 4 Aug by counting aphids on ½ of each of 10 leaves from each of 2 levels (4th leaf down, and one from mid-plant) per plot.