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Northern Corn Leaf Blight becoming a 'concerning' disease issue

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Written Thursday, October 06, 2011  

The continued incidence of Northern Corn Leaf Blight in Ohio fields is increasingly concerning to plant pathologists at the Ohio Agricultural Research and Development Center.

"In the past, we've seen leaf blight show up and not cause much of a problem," said Ohio State University Extension plant pathologist Pierce Paul. "Every single year since 2001 it has shown up in some form or another, which concerns me now because the levels are increasing, and it's showing up in more fields every year."

Paul said the continued and increasing incidence of the disease indicates farmers are still planting corn varieties susceptible to leaf blight. He recommended farmers take stock of fields and varieties that are affected by blight this year, and plant resistant varieties in those fields next year.

He said by continuing to plant susceptible varieties, farmers are in essence ignoring the problem, and allowing the disease to further stress plants in the future.

"If we continue to plant susceptible varieties, at some point we'll build up enough stock of the disease that we're going to see a significant outbreak," he said. "The fungus survives in crop residue, in other words the corn stalks left in the field, and it just builds year over year."

In addition to planting varieties resistant to the fungus, Paul recommends using other management practices to mitigate the amount of fungus left in the field after harvest.

He said farmers can "break the cycle" of the fungus by following a traditional corn-soybean crop rotation. Fields planted corn on corn are more likely to be affected by the disease. He also noted that if tillage is an option, that is another way of reducing the amount of fungus left in a field.

Paul said the biggest problem caused by Northern Corn Leaf Blight is a reduction in the surface area of the leaf available to convert sunlight into plant energy.

"If you have reduced leaf area, the plant will not be able to produce enough sugars for grain development and grain fill," he said. "The plant will redirect sugars from the stalk into those functions, which could pose issues for stalk lodging later in the season. You might think of it as cannibalization of the plant, taking nutrients from one area of the plant to make up for a lack of photosynthetic area."


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