Source: P. Lipps, OSU Plant Pathology
Symptoms:
Gibberella is characterized by pinkish to reddish mold that starts on or near the ear tip and progresses toward the base of the ear.
Cause:
Corn is infected by wind-borne spores of the fungus Gibberella zeae (same fungus causes Gibberella stalk rot). The fungus survives in soil on crop residues. Cool temperatures (average daily temperatures below 72 degrees F) and 7 or more days of rain during the 3-week period after silking favors Gibberella ear rot. This ear rot is associated with several mycotoxins that are lethal to livestock.
Management:
Corn hybrids differ in susceptibility to Gibberella ear rot. Some plant pathologists recommend selecting hybrids with ears that dry in declined position and those well covered with husks. Hybrids with extremely tight husks may be more vulnerable to damage than hybrids with loose husks. Hybrids with Bt resistance to European corn borer may limit ear rot by preventing feeding by borers that may create entry points for fungal infection. Crop rotation and fall tillage can limit the occurrence of the disease by reducing fungal levels in the field.
References:
Ciampitti, I. 2014. Abnormal Corn Ears. Available at https://www.agronomy.k-state.edu/extension/documents/crop-production/Abnormal_Corn_Ears.pdf [URL verified 3/28/2019]. Kansas State University.
Willyerd,W.T., P.A. Paul and P. Thomison. 2016. Gibberella Ear Rot and Mycotoxins in Corn: Sampling, Testing, and Storage. AGNR Fact Sheet PLPATH-CER-04. Ohio State University. Available at https://ohioline.osu.edu/factsheet/plpath-cer-04 [URL verified 1/16/2019].
Lipps, P. E., A. E. Dorrance, and Dennis Mills. 2004. Corn Disease Management in Ohio Bulletin 802.
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].