We all know the old adage, “Rain makes grain.” Unfortunately, some of this year’s rainfall induced growth of nasty ear rots caused by Gibberella and Diplodia fungi.

Gibberella ear rot is the most common of the ear rots this year, however, we have also received reports of Diplodia ear rot in some fields. Diplodia causes a thick white mass of mold to grow on the ear, usually initiating from the base of the ear and growing toward the ear tip.

Diplodia infections can begin before tassel emergence up to silking. With Gibberella ear rot, the fungus enters the ear tips through the silk channel.

A visible white to pink mold covering the ear tip or more of the ears is characteristic of this disease.

Gibberella ear rot is generally most severe when rain and wet weather is prevalent during the 7-10 days after silking.

Dr. Pierce Paul and Dennis Mills, Ohio State University Extension Plant Pathologists, note that the Gibberella ear rot fungus produces mycotoxins that are harmful to animals. These include deoxynivalenol (Vomitoxin) and zearalenone and T-2 toxin, all of which may cause health problems in livestock.

Therefore, suspect grain should be tested for these mycotoxins by chemical analysis before being fed to animals. As a general rule do not feed any grain with 5 percent or more Gibberella moldy kernels. Gestating and young animals, as well as hogs, are particularly sensitive to these mycotoxins.

Diplodia ear rot is less of a concern from a mycotoxin standpoint. There have been no reports of Diplodia producing mycotoxins that are harmful to animals in Ohio, but animals do refuse to eat grain with high levels of Diplodia-damaged kernels. Additionally, severely affected grain has low nutritional value.

Certain hybrids are more susceptible to one or more ear rots than others. Examine ears to determine the presence of ear molds. Make a note of which ear rots are present and hybrids that are most affected. Make future hybrid choices based on this information.

Farmers are advised to follow certain harvest and storage guidelines to minimize problems associated with kernel rots and mycotoxin contamination:

•Harvest at the correct moisture and adjust harvest equipment to minimize damage to kernels. Mold and mycotoxins tend to be higher in (machine or insect) damaged kernels.

•Dry harvested grain to 15 percent moisture and below to prevent further mold development in storage.

•Store dried grain at cool temperatures (36 to 44 F.) in clean, dry bins. Moderate to high temperatures are favorable for fungal growth and toxin production.

•Periodically check grain for mold, insects, and temperature.
•If mold is found, send a grain sample for a mycotoxin analysis to determine if toxins are present and at what level.

For more on moldy grain, mycotoxins, and mycotoxins sampling and analysis visit www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/mycopage default.htm

The views and opinions expressed in this column are those of the author and not necessarily those of Farm World.

Published on Oct. 7, 2009