A guide to late season corn stalk and ear rot diseases
Steps you can take to minimize losses due to ear rot diseases and grain molds:
- Remove old grain from empty bins because it harbors fungi that can infect new grain.
- Avoid further damage to kernels during harvest and handling.
- When possible, avoid storing grain from fields with a high incidence of ear rot diseases, or at least avoid mixing affected grain with healthy grain.
- If storage is necessary, store for a minimum amount of time.
- Cool grain as quickly as possible after harvest.
- Dry grain to less than 15% moisture within 48 hours of harvest to slow further growth of fungi, especially with longer term storage.
- Continue to stir and aerate grain bins during storage to prevent the development of hot spots.
Aspergillus Ear Rot
Aflatoxin is the best known mycotoxin in Nebraska and is produced by the fungus that causes Aspergillus ear rot. At this time there have not been any reports of aflatoxin in the 2013 crop. Hot, dry weather during the latter half of the growing season after pollination especially favors aflatoxin production. Drought-stressed corn, such as that in non-irrigated fields and non-irrigated pivot corners, is especially vulnerable to the accumulation of aflatoxin. Aflatoxin is toxic and carcinogenic to humans and livestock. The FDA has suggested action levels for aflatoxin concentrations, ranging from 0.5-300 parts per billion (ppb), depending on its end use.
Fusarium Ear Rot
Fusarium ear rot is a common disease in hail-damaged corn. Fusarium may infect any part of the ear and take advantage of wounds created by insects or hail. The species that cause this disease also can secrete a mycotoxin called fumonisin into the grain. This mycotoxin is carcinogenic, but is not measured at concentrations as low as that of aflatoxin (up to 50 ppm). Fusarium ear rot is favored by a wide range of environmental conditions and can be recognized by its scattered tufts of mold on the ears that may be white to pink in color and may be accompanied by starburst patterns on the kernels.
Diplodia Ear Rot
Diplodia (also called Stenocarpella) ear rot is a common disease in the Corn Belt. The fungus that causes this disease does not usually produce a mycotoxin in the United States, but can significantly reduce grain quality. Extensive fungal growth usually begins at the base of the ear and can overtake the entire ear, creating a lightweight mummified ear. In addition to these symptoms, it produces small raised, black fungal reproductive structures on infected kernels and stalks that give it a rough feeling when touched, similar to sandpaper.
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