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University of Nebraska–Lincoln

Panhandle Research and Extension Center

Know how. Know now.

Corn Ear Rots and Grain Molds

Tamra Jackson, Extension Plant Pathologist, Dept. Plant Pathology, Lincoln
Michael Carlson, Diagnostic Toxicologist/Analytical Chemist, UNL Veterinary Diagnostic Center
and Robert Harveson, Extension Plant Pathologist, Panhandle REC, Scottsbluff

Cooler and wetter conditions this summer and fall in western Nebraska have delayed harvest and slowed grain drying, leading to increased ear rot diseases and grain molds. Several distinct ear rot diseases have developed throughout Nebraska’s production fields this year, including those caused by Diplodia, Fusarium, Gibberella, and Penecillium.

We often see several of these diseases to some extent each year, but because of the unusual environmental conditions in the Panhandle this year, they are much worse than normal. These diseases may additionally require more unaccustomed management actions to prevent further losses through grain quality reductions and potential mycotoxin accumulations.

Several methods of management may be attempted right now, including scouting fields and drying grain prior to storage. Scouting is recommended to determine the extent of ear rot damage prior to harvest so action can be taken to minimize its impact on grain quality.
Ear rot pathogens may continue to grow during storage and lead to grain mold that can seriously reduce grain quality and lead to major deductions at the elevator. Even under the best growing conditions, grain molds will usually continue to grow and, in some cases, may take over the entire bin. Thus, drying grain prior to storage will slow the growth of fungi in the bin that can seriously reduce grain quality and accumulate mycotoxins.

Specific method to minimize losses due to grain molds:

  • Avoid further damage to kernels during harvest and handling.
  • When possible, avoid storing grain from fields with a high incidence of ear rot diseases.
  • If storage is necessary, store for a minimum amount of time.
  • Dry grain to less than 15% moisture within 48 hours of harvest to slow further growth of fungi.
  • Remove old grain from empty bins because it harbors fungi that can infect new grain.
  • Stir and aerate grain bins during storage to prevent the development of hot spots.

Accumulation of mycotxins in grain is another issue that may need addressing. Mycotoxins are compounds produced by certain fungi as metabolites or by-products of their growth. The best known mycotoxin in Nebraska is called aflatoxin, produced by the fungus Aspergillus flavus.

An aflatoxin problem is not expected to occur this year in Nebraska. Higher than usual aflatoxin concentrations in Nebraska corn are associated with hot, dry weather, which is just the opposite of what has been observed this fall. However, there is more concern about three other potential mycotoxins in the corn crop: vomitoxin, zearalenone, and fumonisin, which are produced by various species of Fusarium and Gibberella.

The presence or absence of visible mold growth does not necessarily mean that mycotoxins are either present or absent. The presence of mycotoxins depends upon several variables, including the specific mold growing on the corn, kernel moisture content and damage, humidity, and temperature. The best way to determine if mycotoxins are present in corn is to have samples analyzed.

Laboratory Analysis

Several of the Nebraska laboratories that conduct mycotoxin analyses are listed below. Before submitting a sample, it's recommended that you contact the laboratory for specific details on how to properly collect and submit samples as well as associated testing fees.

  • Fremont Grain Inspection Department (402) 721-1270
  • Hastings Grain Inspection (402) 462-4254
  • Lincoln Inspection Service (402) 435-4386
  • Omaha Grain Inspection Service (402) 641-6739

For questions related to how mycotoxins affect livestock feed, contact the UNL Veterinary Diagnostic Center at (402) 472-1434.

Additional Resources

Several additional sources of information concerning ear rot diseases in general can be found at http://cropwatch.unl.edu, and http://marketjournal.unl.edu.

More information about mycotoxins: