Source: H. Willson and B. Eisley, OSU- Extension Entomology.
Symptoms:
Ear feeding by European corn borer (ECB) larvae is not limited to any one area. Kernel chewing injury can be found at both ends and along all sides of the ear. Larvae feeding inside the shank may result in ear drop.
Cause:
European corn borer (Ostrina nubilus).
Management:
Treatment may be warranted if 50% or more of the plants have eggs or early larva. Fields having severe 2nd brood ECB infestations should be harvested early to minimize stalk lodging and ear drop. If significant ECB infestations are detected prior to stalk boring, chemical treatment may be applied. For a list of labeled insecticides, see http://agcrops.osu.edu/sites/agcrops/files/publication-files/545%281%29.pdf. Planting of ECB resistant transgenic Bt-Corn is considered the most effective preventive option. Avoid very early and late planting dates if not planting ECB resistant transgenic Bt-Corn.
References:
Cook, K. 2005. Corn Earworm, European Corn Borer, Fall Armyworm, or Western Bean Cutworm: Which One Is Causing the Injury I’m Finding on My Corn Ears? The University of Illinois IPM The Bulletin No. 23 Article 4/October 7, 2005. Available at http://bulletin.ipm.illinois.edu/article.php?id=415 [URL verified 3/28/2019].
Culman, S.W., A. E. Dorrance, R. B. Hammond, G. A. LaBarge, E. M. Lentz, L. E. Lindsey, M. M. Loux, A. P. Michel, H. E. Ozkan, P. A. Paul, L. H. Rhodes, R. M. Sulc, N. J. Taylor, P. R. Thomison, and H. D. Watters. 2014. Corn, Soybean, Wheat, and Alfalfa Field Guide. Ohio State University Extension Ohio Agricultural Research & Development Center Bulletin 827, Columbus, Ohio. https://extensionpubs.osu.edu/corn-soybean-wheat-and-alfalfa-field-guide-pdf/ [URL verified 3/28/2019].
DiFonzo, C. 2018. Handy Bt Trait Table. Michigan State University. Available at https://aginsects.osu.edu/sites/aginsects/files/imce/BT%20Trait%20Table.pdf [URL verified 3/28/2019].
Vincelli, P. 2013. GMOs and Corn Mycotoxins. Grain Crops Update. University of Kentucky. Available at http://graincrops.blogspot.com/2013/08/gmos-and-corn-mycotoxins.html [URL verified 3/28/2019].