Stalk Rots May Take Corn Down Earlier Than You Think

Stalk Rots May Take Corn Down Earlier Than You Think

Corn Illustrated: Start checking now and plan harvesting strategy.

Someone says it every year – check your fields and plan out which ones to harvest first. If it's become so common you ignore it, maybe you should break the habit. Don't ignore it this year. Dave Nanda says the threat is real.

Nanda, seed consultant for Seed Consultants, Inc., says that foliar diseases took over some fields in late August or early September in the Corn Belt. They were held in check until warm weather in late August let gray leaf spot blossom in areas where it is common. Northern corn leaf blight was already set up by cool weather, and has done a number on hybrids that don't have good resistance to the disease.

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Check fields: Inspect fields now and be ready to harvest if stalk rots are setting in. (Photo courtesy of Bob Nielsen, Purdue University Extension)

Nanda believes anthracnose stalk rot may be an issue. He didn't see much of the foliar phase of the disease, but now that stalks are weakened, anthracnose could invade. Look for black dots along the stalk on the outside. Split one open and find deterioration on the inside.

Stalks were set up for stalk rot in two ways. First, foliar diseases came on late. Any stress such as a disease makes the plant more vulnerable to the pathogens that cause stalk rot. Second, many fields will yield lots of corn.

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In some cases, plants moved sugars and carbohydrates out of the stalk at the last minute to finish filling kernels before black layer, Nanda says. Those stalks are also weaker, and subject to lodging from winds, and also more subject to stalk rot due to stress.

Visit your fields and do pinch tests or push tests. Check 100 stalks in a row at various locations. Different hybrids should be tested separately. Plan to harvest the fields with the highest amount of stalk rot, or the least ability to withstand high winds first. That may mean drying wetter corn than you normally like to dry.

The alternative could be much higher field losses. It isn't a big crop until it is in the bin, he concludes.

For more corn news, corn crop scouting information and corn diseases to watch for, follow Tom Bechman's column, Corn Illustrated Weekly, published every Tuesday.

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