Figure 2. Corn Earworm
We have seen a significant increase in conventional field corn production in the state this year, and along with that, questions about controlling corn earworm in conventional corn. Attempting to control corn earworm in the ear is challenging. Moths lay their eggs on the silks. Once eggs hatch, the newly hatched larva make their way down the silk and into the ear where they are protected from any insecticide application. Treating for corn earworm infestations in the ear on field corn is generally not economical or necessary. We conducted research several years ago looking at potential yield loss from corn earworm in field corn and could not measure any significant loss in yield from infestations in the ear (Figure 4). The majority of feeding occurs near the tip of the ear which contributes little to yield. This, coupled with the fact that kernels adjacent to those damaged by earworm, often compensate by enlarging and partially filling in the damaged area. Therefore, it is not necessary to treat for corn earworm infestations in the ear, no matter how effective the insecticide may be.
Figure 4. Yield (Bu/A) in Corn Earworm Infested and and Uninfested Hybrids by Trait
“This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006-27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture.”