Evaluation of Insecticides to Control Lesser C0Nstalk Borer Larvae in Sorghum, 1982

Three tests evaluated the effectiveness of various rates and formulations of chlorpyrifos in preventing damage to seedling sorghum by lesser cornstalk borer larvae. All tests were planted by conventional tillage methods in a Cecil loamy clay soil. Tests 1 and 2 were planted behind wheat on Jun 16 and 23, respectively. Test 3 was planted on Sep 7 following sweet corn. Insecticides were applied immediately after planting. Sprays were directed over the rows with a CO2 backpack sprayer calibrated to deliver 370 1/ha at 2.0-2.2 kg/cm2. Granules were applied over the rows in a 16-18 cm band with a 2-wheeled hand-pulled applicator. A simulated chain drag was used to incorporate materials into the soil. Plots were 6.1 m x 5 rows (91-cm row spacing) and were separated by 2 untreated rows and 1-m alleys. Treatments were replicated 4X in a RCB design in all 3 tests. Control was assessed by examining 50-60 randomly selected plants/plot for lesser cornstalk borer damage 3 wk after treatment. These data were converted to percentage values and transformed (arcsin) before analysis.