Evaluation of in-furrow and foliar insecticidal treatments for the control of thrips (Thysanoptera) on seedling cotton in Tennessee

In-furrow and foliar insecticides are the two most common treatments used to control injurious levels of thrips on seedling cotton. Six in-furrow insecticidal treatments and seven foliar insecticidal treatments were applied at four different locations in the spring of 1976 in the West Tennessee area. These treat-ments were evaluated in regard to thrips control on seedling cotton and also their effect upon plant populations, plant heights, and plant vigor. In-furrow treatments were applied at planting while foliar sprays were applied after the cotton seedlings had emerged. Whole-plant samples were taken from all treated plots exactly one week after the foliar sprays had been applied. The plants were then taken to the laboratory, where the thrips were extracted from the plants and counted. All in-furrow treatments gave excellent control of thrips populations with no treatment giving significantly better results than another. Among the foliar treatments, dicrotophos, monocrotophos, methamidophos, and SD 43775 were judged to give acceptable thrips control. Malathion, azinphosmethyl, and dimethoate were judged unacceptable for use as foliar treatments for the control of thrips infestations.