A dynamic economic threshold for corn earworm (Helicoverpa zea) in sweet corn

For several decades, corn earworms in sweet corn have been effectively managed by applying insecticides when the crop had green silks present and 10 or more moths/night were captured in pheromone traps. This threshold was developed through the experience of pest managers and was primarily used for sweet corn for processing. Recent studies have shown that the rate of oviposition in sweet corn fields is higher relative to pheromone trap catch when the neighboring field corn has not yet reached the reproductive stage or is senescing. This study compared the use of the standard 10 moths/night threshold versus a threshold of 1 moth/night versus calendar sprays in multiple plantings during three growing seasons in Indiana. Results showed that the use of a dynamic threshold which changes based on the stage of development of the neighboring sweet corn resulted lower levels of damage than using a single threshold and fewer insecticide applications compared to calendar based sprays.