Evaluation of Insecticides for Suppression of Sorghum Midge on Sorghum, 1989

Abstract

Abstract One organophosphate, a pyrethroid and 2 carbamate insecticides were evaluated for sorghum midge control at the Texas Agricultural Experiment Station Research Farm near College Station, TX. Grain sorghum was planted 23 May on rows spaced 40 inches apart. Insecticide treatments were compared in 8-row × 75 ft long plots arranged in a randomized complete block design with 4 replications. Insecticides were applied using a self-propelled, high clearance sprayer to the inner 6 sorghum rows through TX-6 hollow cone nozzles at 40 psi with a spray volume of 8 gal/acre. Insecticide applications were begun when 20-50% of the panicles were flowering. Treatments were applied on 14, 18, 21, and 24 Jul. Data on kernel loss and grain yield were collected from the middle 2 rows of each plot. Adult sorghum midge abundance was determined just prior to each application by randomly selecting 100 individual sorghum panicles and then enclosing these with clear plastic bags. Panicles were cut from the plant and returned to the laboratory for examination and determination of numbers of adult midges. Visual estimates of midge damage were made by 2 independent observers on 9 Aug, with each observer rating damage to 10 panicles/plot on a 1-9 scale where 1 = 0-10% and 9 = 90% kernel loss. Panicles were hand-harvested from 2 randomly selected 13 ft sections of row/plot and mechanically threshed.