True Armyworm Control in No-Till Field Corn in West Virginia, 1984

Insecticides were applied as rescue treatments on 14 Jun. Corn was planted in sod fields in 36-inch rows on 18 May. Stage of growth at treatment time was early whorl (4-6 leaves). Pretreat samples showed an average of 48.2% of plants infested with armyworm larvae and 100% of the plants damaged; moderate to heavy feeding damage was prevalent. Larval length averaged 16.3 mm with most (70%) being 14.9 mm. Liquid formulations were applied by hydraulic sprayer delivering 25 gal/acre at 20 psi. Spray treatments were replicated twice, once each in 2 adjacent fields ranging from 690 to 1100 ft long. Six rows were treated in each field for plot sizes ranging from about 0.3 to 0.5 acres. Bait formulations were applied by hand using a cyclone seeder; plots were about 0.2 acre and not replicated. Efficacy was evaluated on the basis of number of plants infested with larvae at 2 and 8 DAT. Sampling consisted of examining 25 plants at 4 equidistant locations (= 100 plants) in one of the center rows of each replication. Precipitation during the test period totaled 1.11 inches (0.13 inches at 3 DAT and 0.98 inches at 5 DAT). Lannate L was used as a standard for treatment comparisons.