Insecticides for Suppression of Carmine Spider Mite on Cotton, 1986

Abstract

Abstract Stoneville 825' cotton was planted 13 May on rows spaced 40 inches apart. All cotton was treated on 4 and 16 Jul with a mixture of .04 lb (AI)/acre cypermethrin and 0.25 lb (AI)/acre Lorsban to engender mite infestation and also to control boll weevil and cotton aphid. The study area received 1.9 inches of rain 3 Aug, 4.13 inches 10-11 Aug (2 days after application of experimental treatments), and 1.25 inches 23-24 Aug. Mite densities in an untreated check plot and 8 insecticide treated plots were compared in a randomized block design with 4 replications. Plots were 6 rows wide and 80 ft long; the middle 2 rows were sprayed. Chemical applications were made with a high-clearance, self-propelled sprayer equipped with three TX-3 hollow cone nozzles/row (using drop nozzles) and calibrated to deliver 5.9 gpa at 42 psi and 3 mph. Acaricide treatments were applied on 8 Aug when average mite density was 8.2 mites/leaf and when chlorotic symptoms were visible on infested leaves. Mite density was sampled prior to application of acaricide treatments and at 4, 10, and 17 days post-treatment. Sampling was accomplished by visually inspecting five pre-selected cotton leaves per plot with a hand lens and counting live (mobile) mites. The sample leaves were located in the lower % of the canopy (mainstem nodes 5-9), and were tagged with plastic surveyor's tape. Mite count data were analyzed by conventional analysis of variance and multiple comparison procedures. Yield data were not collected for this study.