Evaluation of In-Furrow and Side-Dress Insecticide Applications for Thrips and Aphid Control on Cotton, 1990

Abstract

Abstract Thirteen treatments were evaluated for thrips and aphid control on cotton planted 17 May in sandy loam soil on the Plant Science Research Farm, Mississippi State University, Mississippi State, Miss. Soil and ambient temperatures were 24.6 and 22.2°C, respectively, and soil moisture was adequate. Plots were 12 rows by 50 ft (38 inch centers) arranged in a randomized complete block statistical design with 4 replications. Granular material was applied by a John Deere planter equipped with granule applicator boxes. Liquid treatments were applied at planting by use of a CO2-powered sprayer with an 8002E nozzle positioned above and in line with the furrow so as to direct all the spray into the furrow at a volume of 5 gal/acre. Water was used as the carrier for sprayed insecticides. Five treatments received an additional application by side-dressing and 2 treatments received only the side-dressing application. Sidedressing was applied 27 Jun, 2 inches deep by using a John Deere planter offset 8 inches from the seed furrow and with 1 press wheel removed. Liquids were applied at 10 gal/acre. Insect samples were obtained by collecting 5 plants at random from the center 4 rows of each plot, placing them in a plastic bag and transporting them to the laboratory. Samples for thrips on seedling cotton were collected 24 May, 1, 7, 12 and 19 Jun. Plants were washed with a few drops of detergent and sodium hyperchlorite bleach per liter of water, and rinsed onto a 115 mesh sieve. Insects were then rinsed onto filter paper for counting under a binocular microscope. Sampling for aphids after 19 Jun was accomplished by counting insects on each of 10 leaves picked at random in the center 4 rows of each plot from 3 levels of the plant canopy, the fourth fully expanded leaf below the terminal, a leaf arising from the mainstem Vi of the plant height down the plant from the terminal, and a leaf near the bottom of the plant. Rainfall between the planting date and 19 Jun totaled 6.03 inches. Rainfall between 27 Jun and 19 Jul was 3.65 inches. The center 4 rows of all plots were mechanically harvested 9 Oct. All plots received insecticide treatments for nontarget pests as needed during the season. An application of Thiodan at 0.5 lb (AI)/acre was applied 3 Jul to reduce aphids because control from the side-dressing was not noticeable.