Corn Rootworm Control, 1988

Two insecticide evaluation studies were conducted for control of mixed populations of NCW and WCR. Test 1 was conducted at the Pennsylvania Agricultural Experiment Station farm at Rock Springs, Centre County, Pa. Corn was planted no-till 23 May using a 2-row John Deere Max Emerge planter with 30-inch row spacing. Insecticides were applied to 10- by 40-ft plots in a randomized complete block design with 5 replicates/treatment. On 30 Jun plots were thinned to 28,000 plants/acre. Root damage ratings were evaluated 29 Jul, and 1, 2, and 3 Aug taking 5 plants/plot and using the Iowa 1-6 rating scale. Yield was determined by mechanically harvesting 2 rows from each plot for shelled corn. Test 2 was conducted on the Dotterer farm, Clinton County, Pa. Corn (‘Doeblers 75 X’) was planted no-till 9 May using the same 2-row planter. Insecticides were applied to 5-by 20-ft plots in a randomized complete block design with 5 replicates/treatment. Plots were thinned to 28,000 plants/acre 22 Jun. Root damage ratings were evaluated 18 and 19 Jul, taking 4 plants/plot and using the Iowa 1-6 rating scale. Yield was determined by mechanically harvesting each plot for shelled corn.