Control of Cotton Leafperforator, 1981

Abstract

Abstract Four insect growth regulating compounds were tested against the cotton leafperforator in a field of short staple cotton on the Arizona State University research farm, Maricopa Co, AZ. The treatment materials were: Thompson-Hayward diflubenzuron, TH-6043, TH-6044 (all WP 25 formulations), and Maag Agrochemicals R0 13-5223 (WP 50). Each was formulated in water at a rate of 0.125 and 0.25 lb ai in 20 gal spray/acre and applied with pressurized 3-gal hand-held sprayers. Attention was given to coverage of upper and lower leaf surfaces of the upper third of each plant. Three replicate plots, 4 rows x 25 ft, for each treatment plus control were arranged in a randomized block design through the center of the field. Plots were sprayed at approximately weekly intervals beginning Aug 19 and ending Sep 22, a total of 5 applications. Samples of 50 leaves/plot were taken from the new leaves at the tops of the plants on Sep 10 and Sep 29. Each leaf was appraised for damage using 3 categories: 1) presence of leaf mines, 2) presence of perforations or ‘windows’ made by larvae feeding on the lower leaf surface, and 3) horseshoes (larvae in webbing between 4th and 5th instars). The percentages of damaged leaves were normalized by an arcsine transformation and then subjected to analysis of variance to test for significant differences between means. Duncan’s multiple range tests were used to separate means into significant ranges.