Effects of Timing and Insecticide on Management of Helicoverpa zea (Lepidoptera: Noctuidae) in Sweet Corn (Poales: Poaceae)

Helicoverpa zea Boddie (Lepidoptera: Noctuidae), the corn earworm, is a key pest of sweet corn (Poales: Poaceae) in many parts of the United States. Integrated pest management (IPM) practices for H. zea in fresh and processing sweet corn use pheromone trap counts of male moths for management decisions. In this study, we examined whether sweet corn could be protected more effectively if insecticides were applied to target the most attractive silking periods for female H. zea oviposition instead of current IPM practices using pheromone trap catches alone. Specifically, we investigated the relationship between insecticide application timing from tassel through silk stages and marketable yield at harvest. We also evaluated the effectiveness of 3 registered insecticide products with different active ingredients (methomyl, chlorantraniliprole, and lambda-cyhalothrin), under various timing scenarios. Results were compared with yields obtained using current IPM recommendations for the northeastern United States. Reduction of H. zea damage in sweet corn among insecticides and timing treatments varied within and between years. In year 1, only interaction effects between insecticide and timing were significant, but in year 2, only main effects of insecticide and timing were significant. Chlorantraniliprole produced inconsistent results in year 1 but had significantly higher percentages of clean sweet corn ears compared with lambda-cyhalothrin in year 2.