COLUMBUS – An old corn disease has re-emerged in Ohio fields, raising concerns of potential problems it may cause if not controlled.
Northern corn leaf blight, a fungal disease that can cause significant yield losses under wet weather conditions, has been found in cornfields throughout southern Ohio this season. The disease was last seen in Ohio in the early 1990s.
Pat Lipps, an Ohio State University plant pathologist, said the disease could cause serious problems.
“The cases we’ve been finding in Ohio are not severe enough to be a major epidemic, but it’s enough to give us a warning sign that we need to pay attention to this,” he said.
Why now? Plant pathologists speculate the disease has returned because some corn hybrids planted lacked resistance.
“The best way to control the disease is through resistance,” Lipps said. “It’s cheap and effective.”
Northern corn leaf blight is more common in fields throughout southern Ohio because of the ample rainfall the region received during the growing season. A number of fields with higher disease levels are experiencing 10 percent to 20 percent yield losses, Lipps said.
Symptoms. The telltale sign of northern corn leaf blight is 1- to 6-inch cigar-shaped, gray-green to tan-colored lesions on the lower leaves.
As the disease develops, the lesions spread to all leafy areas, including the husks. Lesions may become so numerous that the leaves are eventually destroyed, causing major reductions in yield due to carbohydrate deficiencies available to fill the grain.
Yield losses can reach as high as 50 percent if the disease establishes itself before tasseling.
Two types of resistant hybrids are available to farmers to control northern corn leaf blight. Partial resistant hybrids are the most common and protect against the four known races of the fungus. Race-specific resistant hybrids protect against a specific race.
A 1- to 2-year rotation away from corn and destruction of old corn residues by tillage may be helpful in controlling the disease if susceptible hybrids must be grown.
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