Evaluation of Selected Insecticides for Control of Corn Earworm in Grain Sorghum, 2015 ^*

Selected insecticide treatments were evaluated for control of corn earworm in grain sorghum at the Research and Education Center at Milan, TN. Grain sorghum was planted on 13 May. The test was arranged in an RCB design with four replicates. Individual plots were 12.5 × 30 ft. Treatments were applied with a high clearance sprayer calibrated to deliver 9.4 GPA at 40 psi with 8,001 flat fan nozzles. Foliar application was made on 30 Jul. Plots were sampled by bending and vigorously shaking 10 sorghum heads from the center two rows of each plot into a standard 15-in. sweep net. Insect control was evaluated on 5 Aug, 6 days after treatment (6 DAT) and 10 Aug (11 DAT). Yield data were collected on 17 Sep by harvesting two center rows of each plot with a plot combine. Data were subjected to ANOVA and means were separated using a protected Least Significant Difference (LSD).

All insecticide treatments significantly reduced the numbers of total corn earworm larvae found at 6 and 11 DAT ( Table 1 ). Belt and the lower two rates of Prevathon provided better control of small corn earworm 6 DAT than Besiege alone or Karate Z. Besiege alone or with fungicide, all rates of Prevathon, and the higher rate of BlackHawk had fewer large corn earworm than did the lower rate of BlackHawk 6 DAT. Also at 6 DAT, Karate Z provided significantly less control of total corn earworm larvae than all treatments except the low rate of BlackHawk and Besiege applied alone. By 11 DAT, Karate Z provided significantly less control of large and total corn earworm than all other insecticide treatments. There were no significant differences in yield among treatments. No phytotoxicity was observed with any treatment.

Author notes