Evaluation of Ovasyn Mixtures Against Tobacco Budworm and Bollworm, 1991

Abstract

Abstract Cotton was planted 12 Jun with plots consisting of 5 rows (102 cm centers) x 15 m. Treatments were arranged in a RCB design, replicated 4 times. Applications were made with a high clearance sprayer calibrated to deliver 56.2 liters total spray/ha through Teejet X-8 hollow cone nozzles (2/row) at 3.02 kg/cm2. Insecticide treatments were applied on 12, 23, 30 Aug and on 5, 20 Sep. Methyl parathion 4 EC (0.37 kg [AI]/ha) was applied on an “as needed” basis for boll weevil control. Efficacy was determined by examining 25 squares/plot for evidence of damage and the presence of larvae. In addition, the number of harvestable and larval damaged bolls/3.3 m section of row was recorded on 17 Oct. High numbers of soybean looper larvae were observed in the plots during Sep and visual defoliation ratings were estimated to evaluate differences among treatments. Each plot was scored as follows: 0 (no feeding damage), 1 (feeding damage within the lower 1/3 of the plant), 2 (feeding damage in the lower 1/3 and middle 1/3 of the plant) or 3 (feeding damage throughout the plant). The plots were mechanically harvested on 17 and 24 Oct to estimate seed cotton yields. The test area received 1.5 cm rainfall on 29 Aug, 2.8 cm rainfall on 30 Aug, 2.0 cm rainfall on 1-3 Sep, and 4.7 cm rainfall on 5 Sep. Additional moisture was provided by sprinkler irrigation “as needed” during the season but not within 48 h of treatment applications.