Corn Earworm and European Corn Borer Control Programs in Sweet Corn, 1979

Abstract Sweet corn was planted Jun 25 (app. 1000 HU50) so that ear formation coincided with expected European corn borer (1550 HU50 to frost) and corn earworm (1950 HU50 to frost) flight activity. Fifteen chemical treatments and 3 stratified untreated checks were replicated in 2 sets of 4 randomized complete blocks 100 ft × 120 rows per block. One additional block in each set was left untreated. Six border rows were left on the edge of each block. Each treatment consisted of six rows with no border rows between treatments. One set of treatments, a short interval program, was applied Aug 15, 21, 24, 27, 30, and Sep 3 at 1739, 1857, 1908, 1965, 2030, and 2120 HU50, respectively. The second set, a long interval program, was applied Aug 15, 23, 28, and Sep 3 at 1739, 1895, 1984, and 2120 HU50, respectively. All materials were applied with a modified Hagie Hiboy (20 gpa, 2 mph, 40 psi, or 10 gpa, 4 mph, 40 psi) with two D2/23 Tee Jet tips per row. Application interval was adjusted to weather conditions and moth activity. At harvest, 10 days after the last treatment, 25 ears from the middle two rows of each replicate were examined for damage to each ear as “none” (clean), “tip” (kernels eaten), “side”, or “tip and side”. Each ear was assessed for the number of European corn borer and corn earworms in the early, mid, or late instar stage. European corn borer and corn earworm flight activity during the trial was average, based on a 20 year summary. The untreated checks were 81% damaged and 85% infested with an average of 0.8 European corn borer and 0.4 corn earworm per ear.