Evaluation of Five Insecticides for Control of the Bandedwing Whitefly and Cabbage and Soybean Loopers in Cotton, 1977

Abstract

Abstract Stoneville 213 acid delinted seed was planted on May 11‘77 at 10 lb per acre. Treatments were placed in plots 8 rows (40-inch) by 40 ft and replicated 4 times in a randomized complete block design. Insecticide applications were made with an International 660 Hi-Clear sprayer with a compressed air system equipped with 2 X-3 hollow cone spray tips per row delivering 2.5 gpa at 3.5 mph and 60 psi. Four applications were made between Aug 10 and 25. Plots were not irrigated. Rainfall was moderate and did not affect applications. The pretreatment whitefly infestation count was 52 percent infested terminals on Aug 8. Separate applications of EPN + Methyl Parathion (0.5 + 0.5 lb Al/A) were applied on Aug 1, 5, 10, 15, 19, 25, and Sept 15 and one application of Pounce (0.1 lb AI/A) on Sept 26 was used on all plots for boll weevil and Heliothis spp. control. Twenty randomly selected terminal leaves per plot were col-lected on four observation dates and placed in plastic bags and frozen for later observation in the laboratory. Assessments of the whitefly populations were accomplished by counting the immature whiteflies in a 2.25 square centimeter area adjacent to the central leaf vein. Subsequent looper populations developed in the test and on Aug 29 a defoliation index rating was obtained based on the average ratings of three observers. The looper populations on Aug 25 were composed of 70% Trichoplusiani (Hubner) and 30% Pseudoplusiaincludens (Walker).