Sorghum Midge Suppression on Sorghum, 1997

Abstract

Abstract The efficacies of 13 insecticides to control sorghum midge were evaluated at the Texas Agricultural Experiment Station Research Farm near College Station, TX. Seed of 6 sorghum hybrids of different maturity rates was mixed together and planted 29 May on rows spaced 30 inches apart. Mixtures of hybrids of different maturity were used to simulate sorghum with nonuniform flowering as often occurs in fields of sorghum. Insecticide treatments were compared in plots 6 rows X 40 ft long, arranged in a RCB design with 4 replications. Insecticides were applied to the middle 2 rows of plots. Insecticides were applied between 0630 and 0930 h CDT by using a hand-held backpack sprayer with 4, TX-3 hollow cone nozzles at 35 psi, producing a finished spray volume of 4.9 gpa. Insecticides were applied on 24 (when 10-50% of the panicles were flowering), 28, and 31 Jul (when 95-100% of panicles were flowering). Just before the 1st application, 10 panicles per replication of each treatment were enclosed individually in clear plastic bags, and the panicles were cut and taken to a laboratory where the number of adult sorghum midges were counted. Prior to the 2nd and 3rd applications, 5 panicles per plot were visually inspected and the number of adult sorghum midges recorded. Data on kernel loss and grain yield were collected from the 2 treated rows of each plot. Panicles in these rows were visually rated for kernel damage based on a scale of 1-9, where 1 = 0-10% to 9 = 81-90% kernel loss. Panicles were hand harvested from 2, 8.75-ft sections of treated row per plot and mechanically threshed. Data were statistically analyzed by using ANOVA and LSD.