Control of Bird Cherry-Oat Aphid in Barley, 1990

Efficacy of selected insecticides was evaluated against a spring aphid infestation in barley in adjacent small and large-plot tests in Charles City County, Va. Barley was planted on 8 Oct, 1989, using a 6-inch row spacing. Di-Syston 8 E at 1.0 lb (AI)/acre was applied with fertilizer before planting. In the small-plot test, treatments were applied on 9 Apr, 1990, using a CO2-pressurized backpack sprayer calibrated to deliver 25 gal formulation per acre at 18 psi, broadcast through 8004VS flat fan nozzles spaced 18 inches apart on the boom. A randomized complete block experimental design was used with 4 replicates; plots were 6 rows by 20 ft. In the large-plot test, treatments were applied on 10 Apr, 1990, using a high-clearance, high-cycle sprayer to 48 ft wide by 300 ft long strips. Treatments were assigned randomly using 3 replicates. Treatments were evaluated by comparing numbers of aphids per row-ft 2 h before and 2, 7, and 14 DAT in the small-plot test, and 1, 6, and 13 DAT in the large-plot test. Yield was determined in the large-plot test by combining and weighing grain from a 15 ft wide by 300 ft long swath from the center of each strip using a John Deere 7720 combine.