By JEFF BURBRINK
Extension Educator, Purdue Extension Elkhart County
There have been some scattered reports of ear rots coming in from around the state and Midwest. Warm, wet conditions as grain dries down could favor the development of ear rots. In Indiana, corn pathologists and agronomists have reported scattered Diplodia ear rot. In Illinois, there are reports of grain being turned away from elevators because of poor quality due to Diplodia ear rot. The Iowa State University Grain Quality Lab also reports a variety of ear rot fungi, and some individual ears display symptoms of multiple types of fungi.
Some ear rot diseases are capable of producing mycotoxins, which can result in marketing restrictions for affected grain or make the grain undesirable to feed livestock. The risk at this point is not 100 percent clear – fumonisins, deoxynivalenol (vomitoxin), aflatoxin, and zearalenone are all potentially out there somewhere in the state.
Diplodia ear rot is common in wet conditions following silking. Diplodia doesn’t result in mycotoxin production that could make livestock sick, but will still affect the quality and test weight of the grain being sold. Feed quality and palatability for livestock may be reduced. Diplodia is usually a white to grayish-brown mold which starts at the base of the ear and works its way towards the tip. Infected ears are lightweight.
Cooler and wetter weather around silking time also favors Gibberella and Fusarium ear rots.
Gibberella is the most feared because it can produce a couple different mycotoxins including DON (deoxynivalenol) which can be harmful to livestock, especially swine. Gibberella will appear as a pink to reddish color mold usually beginning at the tip of the ear. It will work its way towards the base of the ear and will be matted in between the kernels. Silks and husks may seem glued to the ear.
It is important to scout fields to determine if ear rots are a problem. If greater than 10 percent of the ears are moldy, fields should be scheduled for an early harvest to prevent further deterioration of grain. Special precautions may need to be taken to protect your lungs while handling moldy grain.
Literature with good color photos on ear rots and mycotoxins is available on the internet.