EVALUATION OF FOLIAR-APPLIED INSECTICIDES TO CONTROL PESTS OF SOYBEAN, 2013

Abstract

We established a trial at the Northern Illinois Agronomy Research Center near DeKalb, IL, to evaluate the efficacy of foliar-applied insecticides to control insect pests of soybean. The experimental design was a RCB with four replications. The plot size for each treatment was 10 ft (four rows) x 20 ft. The trial was planted on 11 Jun using a 4-row, John Deere 7300 planter. Seeds were planted at a population of 150,000 seeds/acre in 30-inch rows at an approximate depth of 1 inch. The variety used for the trial was NK S31-L7. Insecticides and fungicides were applied on 8 Aug with a CO2-powered backpack sprayer and a four-row boom. TeeJet TTJ60-11002 spray tips were calibrated to deliver a volume of 20 gpa. Densities of corn rootworm beetles were determined by taking 20 sweeps per plot with a 15-inch diameter sweep net. Densities of soybean aphids were determined by counting the total number of aphids on three plants in each plot. Densities of corn rootworm beetles were assessed on 8, 15, 22, and 29 Aug (0, 7, 14, and 21 DAT, respectively). Populations of soybean aphids were not detectable until late Aug; because of this, aphid densities were not evaluated until 22 Aug (14 DAT). Yields were estimated by harvesting the center two rows of each plot on 29 Oct. Weights were converted to bu/acre at 13% moisture. Data were analyzed using ARM 8, revision 8.5.0 (Gylling Data Management, Inc., Brookings, SD).