Part of the ear or the entire ear is rotted by a white mold growing between the kernels. Infections generally start at the base of ear and progress to the tip. Later the white mold changes to a grayish-brown growth over the husks and kernels. The entire ear may be shrunken. Infected kernels appear glued to the husks. Although feed quality and palatability may be reduced, Diplodia ear rot is not associated with mycotoxins.
Diplodia ear rot is caused by the fungus Stenocarpella maydis. Infection may occur from late vegetative stages to three weeks after midsilk. It is more common in southern half of Ohio and appears to be associated with continuous corn and reduced tillage. Warm dry weather prior to silking followed by wet conditions following silking favors ear rot.
Planting resistant hybrids is the most effective way to control Diplodia ear rot. Crop rotation and fall tillage can reduce the occurrence of the disease by reducing fungal levels in the field. Dry harvested grain to 15% and below to prevent further mold growth in storage.
Lipps, P.E. and D.R. Mills. 2001. Diplodia Ear Rot of Corn. Ohio State University Plant Pathology Fact Sheet AC-0046-01.
Lipps, P. E., A. E. Dorrance, and Dennis Mills. 2004. Corn Disease Management in Ohio Bulletin 802. Available at https://agcrops.osu.edu/publications/corn-disease-management-ohio-bulletin-804 [URL verified 4/12/2018].
Lipps, P.E., P.Thomison, B.Weiss. 2004. Diplodia Damaged Corn Grain: Assessing Feed Value. C.O.R.N. Newsletter 2004-38. Available at http://agcrops.osu.edu/newsletters/2004/38#4 [URL verified 4/12/2018].
Paul, P., P. Thomison, and D. Mills. 2005. Corn Ear Rot Problems in Ohio. C.O.R.N Newsletter 2005-34 (October 10, 2005 – October 18, 2005). Available at http://agcrops.osu.edu/newsletters/2005/34#1 [URL verified 4/12/2018].