Sponsored By
Farm Progress

Heads up for stalk rot in cornfieldsHeads up for stalk rot in cornfields

Fields where stalk rot is present should be identified and harvested early to minimize grain losses.

Rod Swoboda 1

October 2, 2016

4 Min Read

“It seems like I have written an article on stalk rot about every year for the last five or six seasons,” says Iowa State University Extension agronomist Clarke McGrath. “Luckily for the most part the last few years it was a ‘heads up’ about a relatively small amount of fields that were having lodging issues. This year, however, it sure seems like stalk integrity issues are a lot more prevalent across the state than they have been in years.”


So, should you harvest soybeans first or corn? The short version is yes, “we have to get these beans out while the getting is good,” says McGrath. “But when we get caught up with soybean harvest and can get into the corn, we should prioritize harvesting the areas of cornfields where the stalks are weak.”

It’s risky to try to let corn “field dry” in fields with weak stalks

This year, 2016, is one of those growing seasons when it might not be a question of if you’ll have stalk rot, but rather where and how much. “While we like to take advantage of as much field drying of corn as possible,” he says, “I’ve been in quite a few fields already this fall, and have had calls on many others, where it would be pretty risky to leave the corn out there in the field very long.”

ISU Extension plant pathologist Alison Robertson recommends the following procedure to assess your fields before harvest. If you are scouting for stalk rot, look for lower stalk discoloration, and check stalk firmness by pinching the lower internodes.

Give stalks to “pinch test” now to prioritize fields for harvesting

Simply pinch the stalk between your thumb and fingers. Healthy stalks are firm and won’t compress easily; if a node can be “squished” or if it otherwise feels soft, that means stalk rot has set in and risk of lodging goes up. Instead of this “pinch test,” some agronomists and farmers prefer using the “push” test, but either way works fine. Check at least 100 plants per field; 20 plants in five spots.

“Better yet, try to test each of your hybrids, with special attention given to any that have low stalk rot or standability scores,” says McGrath. “So far I have seen hybrids that varied from maybe 2% to 4% of the stalks being soft to some hybrids that were well over 50% of the stalks being soft. To complicate the issue, often individual hybrids are varying quite a bit across a field.”

Be especially cautious about fields that showed stress first

This has McGrath recommending that growers try to sample the different “management areas” they have in a field and assess them separately: various tillage systems, crop rotations, drainage issues and fertility histories.

McGrath is telling farmers: “Prioritize your scouting toward fields that showed stress first, especially if they’ve had foliar diseases this summer. Also, scout first in areas of fields where there was excess water on and off through the season. If about 10% or greater of the stalks have issues, do your best to get those hybrids harvested first to reduce the risk of significant lodging.”

Also, you should scout fields now for corn ear rots

Warm, wet conditions as grain is drying down in the field favors the development of ear rots, and we had that kind of weather this year, notes McGrath. In the eastern Corn Belt, university plant pathologists report that diplodia ear rot is prevalent (read the C.O.R.N. NewsletterThe Bulletin; and the Pest and Crop Newsletter). In Illinois, there are reports of grain being turned away from elevators because of poor quality due to diplodia ear rot. 

It is important to scout fields to determine if ear rots are a problem. If greater than 10% of the ears are moldy, fields should be scheduled for an early harvest to prevent further deterioration of grain. ISU grain quality expert Charlie Hurburgh has some tips for grain handling and storage. Publications and training modules are available for folks who would like to learn more. The Crop Protection Network recently posted publications on corn ear rots and mycotoxins that are available for download. Moreover, the Iowa Grain Quality Initiative has a training module describing mycotoxin development.

About the Author(s)

Rod Swoboda 1

Editor, Wallaces Farmer

Rod, who has been a member of the editorial staff of Wallaces Farmer magazine since 1976, was appointed editor of the magazine in April 2003. He is widely recognized around the state, especially for his articles on crop production and soil conservation topics, and has won several writing awards, in addition to honors from farm, commodity and conservation organizations.

"As only the tenth person to hold the position of Wallaces Farmer editor in the past 100 years, I take seriously my responsibility to provide readers with timely articles useful to them in their farming operations," Rod says.

Raised on a farm that is still owned and operated by his family, Rod enjoys writing and interviewing farmers and others involved in agriculture, as well as planning and editing the magazine. You can also find Rod at other Farm Progress Company activities where he has responsibilities associated with the magazine, including hosting the Farm Progress Show, Farm Progress Hay Expo and the Iowa Master Farmer program.

A University of Illinois grad with a Bachelors of Science degree in agriculture (ag journalism major), Rod joined Wallaces Farmer after working several years in Washington D.C. as a writer for Farm Business Incorporated.

Subscribe to receive top agriculture news
Be informed daily with these free e-newsletters

You May Also Like