Western Corn Rootworm Control, 1986

This experiment was conducted in Clay County, Neb. The previous year's crop was a trap crop of mixed-maturity corn and pumpkins. The experiment was set up in a split plot design in which the main plots were insecticide treatments and the subplots were application methods. Main plots (4 rows) were randomly placed within each replication (6) and subplots (1 row) were randomly assigned within each main plot. Rows were spaced 30 inches and were 37 ft long. On 23 Apr, planting-time application of granules was made by applying granules from a V-belt seeder mounted on the planter into the granule delivery tube, which directed the granules to just in front of the press wheel through a 7-inch bander. Additional incorporation was accomplished in the raked treatment by dragging a three-tined pitchfork along the row after passage of the planter. On 2 Jun, foliar application of granules was made by applying granules over the top of the plants with a V-belt seeder mounted on a cultivator. Corn rootworm damage was assessed by digging 5 plants per treatment per replication on 14-18 Jul (early tassel stage), washing soil from the roots, and rating each root on a 1-6 (Iowa) scale (1, no damage, to 6, S3 nodes destroyed). The corn was harvested 8-10 Oct.