Corn with Mold: Which Mold is it and How to Handle

The following article was sourced from material developed by Gene McCluer, OSU Extension; Purdue University Professor Richard Stroshine; and the October 12, 2009 CORN Newsletter.

Farmers across Ohio are finding mold on corn in some fields this year. Both Diplodia and Gibberella molds have been reported, and they may cause challenges in grain handling and storage this year.  The cool, wet weather over the past month has prolonged conditions favorable for ear mold growth. At this point in the season, producers should scout remaining fields of corn and take note of areas and hybrids with ear rot problems. If Gibberella is present and the crop is insured, contact your insurance provider before harvesting the field to determine if adjustments are needed.

Generally, it is fairly easy to tell ear rots apart based on the color of the fungal growth on the ear, how the mold develops, and how the moldy kernels are distributed on the ear:

• With Gibberella ear rot, a pinkish mold starting at the tip and progressing toward the base of the ear is very typical of this disease.
• Fusarium ear rot also causes pinkish discoloration of infected kernels, however, with Fusarium ear rot the pink moldy kernels are usually scattered all over the ear. As the disease develops, the infected kernels may become tan or brown or have white streaks.
• Diplodia on the other hand causes a thick white mold to grow on the ear, usually starting from the base and progressing toward the tip. As the disease develops, the entire husk becomes bleached, covered with whitish-gray mold, and glued to the kernels.

There are no mycotoxins known to be associated with Diplodia ear mold, but there is a big concern with Gibberella ear mold. It can produce high levels of the mycotoxin DON (also known as vomitoxin). Early reports indicate that levels in corn grain range from 0.2 to 8 ppm, of this mycotoxin, and that can be a concern if grain is to be used for livestock feed. Zearalenone, also produced by this ear rot fungus, has estrogenic properties, which lead to infertility, abortion, or other livestock breeding problems. As little as 1 to 5 ppm zearalenone in a feed ration may produce an estrogenic effect in swine.

Purdue University professor, Richard Stroshine a said that if farmers try to operate like they normally do during harvest this year, the mold could cause some major problems during the storage of this year’s crop. Stroshine offers tips and advice for farmers in the Eastern Cornbelt who are dealing with Diplodia, Gibberella and other corn ear rots. Farmers who have moldy corn should remove as much of the fine material or broken pieces of corn as possible before storage. Use the combine’s full capabilities to help get rid of the fine material, and utilize high capacity screen cleaners as the corn enters the grain handling system. If fines aren’t removed from the grain, they will reduce airflow (primarily in the center of the bin) and promote the growth of mold within the grain. Proper aeration will help maintain even grain temperatures throughout the grain mass. Plan to dry the grain down to 14 to 14.5 percent moisture, but realize it’s not going to store as well as it has in previous years.

Even though it may slow down harvest, Stroshine recommends drying corn to below 15 percent moisture as soon as possible to help prevent any further mold issues.

Farmers may want to mix the corn with high levels of mold with their good corn, but Stroshine suggests segregating the good corn from the bad for storage. It should be handled separately, then if needed, the producer can blend it later to meet the marketing standards.

For more information on corn ear molds, see the OSU/OARDC Plant Pathology website at:

http://www.oardc.ohio-state.edu/ohiofieldcropdisease/corn/corn2.htm

Also see the Purdue website about Gibberella ear mold at:

http://www.agry.purdue.edu/ext/corn/news/others/2009/Gibberella-1002.pdf

SUMMARY

Gibberella ear rot:

• Pinkish mold starting at the tip and progressing toward the base of the ear
• mycotoxins a concern

Fusarium ear rot:

• Pinkish or tan moldy kernels scattered on the ear.

Diplodia ear rot:

• White mold growth starting at the base and moving up the ear
• Husk glued to kernels
• Lightweight ears
• no mycotoxins

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