(F65) GRAIN SORGHUM: Sorghum bicolor (L.) Moench, 'Terral 1050' EVALUATION OF INSECTICIDES AGAINST SOUTHWESTERN CORN BORER AND SUGARCANE BORER IN GRAIN SORGHUM, 2003 E. A. Peters LSU AgCenter Department of Entomology 402 Life Sciences Bldg. Baton Rouge, LA 70803 Phone: (225) 578-1839 Fax: (225) 578-1643 E-mail:
[email protected] D. R. Cook R. H. Gable LSU AgCenter Macon Ridge Research Station, 212A Macon Ridge Rd. Winnsboro, LA 71295 B. R. Leonard Sugarcane borer (SCB): Diatraea saccharalis (F.) Southwestern corn borer (SWCB): Diatraea grandiosella (Dyar) Selected insecticides were evaluated against SWCB and SCB at the Macon Ridge Research Station near Winnsboro, LA (Franklin Parish). Grain sorghum seed were planted into a Gigger-Gilbert silt loam soil on 10 Jun. Plots consisted of 4 rows (centered on 40-inches) × 40 ft. Treatments were arranged in a RCBdesign with three replications. Insecticides were applied to grain sorghum on 4 Aug with a high-clearance sprayer and CO 2 charged system calibrated to deliver 5 gpa through TX-8 hollow cone nozzles (2 per row) at 48 psi. At the time of application seed heads had emerged from the whorl on 10-20% of plants across the test area. SWCB (70%) and SCB (30%) had infested 10% of the plants. Insecticide efficacy against SWCB and SCB was evaluated on 15 Sep by examining 10 plants within each plot and recording total number of bored stalks. Plots were harvested on 19 Sep to estimate yields for each plot. Decis 2EC (0.02 lb (AI)/acre) and Lannate 2.4LV (0.24 lb (AI)/acre) were applied across all plots on 12 and 25 Aug, respectively, for control of sorghum midge and a complex of headworms. Data were analyzed according to ANOVA and means separated according to DMRT (P ≤ 0.05). No rainfall occurred within seven days of treatment application. All insecticide treated plots had significantly fewer bored stalks than that in the non-treated plots. Grain yield in all insecticide treated plots was significantly greater than that in the non-treated control. Plots treated with Intrepid (0.062 lb (AI)/acre) yielded significantly less than those treated with Mustang Max. There was no phytotoxicity observed with any of the treatments.
