Late-Season Tobacco Hornworm Control in Georgia Flue-Cured Tobacco, 1997
Abstract Flue-cured ‘K-326’ tobacco was transplanted on 1 Apr at the Georgia Coastal Plain Experiment Station Bowen Farm. Production practices were used according to Georgia Cooperative Extension Service guidelines and included a preplant tank mixture of Tillman, Devrinol, Ridomil, and Nemacur. Fertilizer (6-6-18) was applied at the rate of 1000 lb/acre in a split application. On 24 Jun, tops were removed and leaves stripped from all plants in the test area, and 16-0-0 fertilizer was applied at a rate of 100 lb/acre. In early Jul, all suckers except the 2 main shoots were removed from each plant. On 16 Jul the test site was partitioned into 24 plots that were 4 rows wide X 20 ft long, with 6 plots power range (replication) arranged in a RB design with 4 replications. The left row of each plot was left untreated (fallow border row) and the remaining 3 rows were treated with a selected insecticide using a CO2-powered backpack sprayer equipped with three TX-12 nozzles per row at 40 psi. One treatment served as an untreated control. The number of live hornworm larvae on plants 2-6 on the middle treated row was recorded from each plot 2, 5 and 8 d after treatment (DAT). Treatments were reapplied on 25 Jul and hornworm counts taken 3, 7, and 10 DAT. On 4 Aug, plants 2-6 on the center row were visually rated for % defoliation and also rated for aphid infestations. Aphid ratings ranged from 0 to 7, with 0 = no aphids, 1 = > 10 aphids/plant, 2 = 10-100 aphids/plant, 3 = 100-500 aphids/plant, 4 = 500-1500 aphids/plant, 5 = 1500-3000 aphids/plant, 6 = 3000-5000 aphids/plant, and 7 = > 5000 aphids/plants. All count data and defoliation and aphid ratings were subjected to analysis of variance and the means were separated using DMRT (P = 0.05).