Sweetpotato Whitefly Control on Cotton, 1991

Abstract

The study was conducted at the USDA-ARS Irrigated Desert Research Station at Brawley, CA. The experiment was conducted in a randomized complete block design with 4 replications. Cotton seed was planted 13 Mar in 40-inch row spacing (30,000 plants/acre). Each plot was 4 rows wide and 40 ft long. Plots were separated by 4 untreated rows on each side and 10 ft fallow alleys between replications. Temik 15 G and Bay NTN 33893 240 FS were applied on 2 Jul when cotton plants were in the first flower growth stage. Temik soil applications were made at rates of 0.75, 1.50, 2.25, and 3.0 lb (AI)/acre, and chiseled 2.5 inches deep at a distance of 8 inches from plants. Foliar applications of NTN 33893 were applied with a backpack sprayer at 0.23 lb (AI)/acre in 22 gal of spray/acre 4 times at biweekly intervals beginning 2 Jul. Plots were sampled 8 times at weekly intervals from 5 Jul to 20 Aug. Ten leaves numbered 6th or 7th from the top fully expanded leaf on the main stem were collected from 1 of the 2 center rows of each plot on each sampling date. The SPW population was estimated by counting. Third and fourth instars on the underside of two 1.55-inch2 leaf disks from each leaf with the aid of a microscope. Seed cotton was hand harvested from two 13-ft sections of row in each plot on 11 Sep to determine the treatment effects of yields.