Corn disease spreading; experts expect it here

A bacterial infection of corn called Goss’s wilt has been confirmed in four northeast Louisiana parishes — the farthest south it has been found, the LSU AgCenter says. And though it hasn’t yet shown up in Mississippi and Arkansas, experts there say it’s sure to happen.

The disease creates circular patches of dead and wilting corn, said AgCenter plant pathologist Clayton Hollier.

If leaves are infected, watery brown patches with dark water-soaked “freckles” near their edges will follow a wavy path along the veins. The bacteria also exude liquid that glistens when wet and dries to a shellac-like appearance. If it infects the system that carries moisture and nutrients throughout the plant, the stalk rots and becomes slimy, agriscientists say.

Since it was first identified in 1969 in Lexington, Neb., Goss’s wilt has been found in Kansas, Colorado, Wyoming, South Dakota, Iowa, Illinois and Wisconsin, according to an article on the University of Nebraska-Lexington website. “Until recent years the disease has not been a serious problem, but has re-emerged, particularly in the tri-state region of western Nebraska, northeast Colorado, and southeast Wyoming,” plant pathologist Tamra Jackson wrote.

Hollier said confirmation of the disease “was a surprise to us because there’s a big gap between that historically developed area of the Midwest with Goss’s wilt and where we are.” Louisiana also grows far less corn. According to USDA statistics, Nebraska planted about 10.2 million acres this year and Kansas about 4.5 million. Arkansas planted 1 million, Mississippi 950,000 and Louisiana 750,000, according to the National Agricultural Statistics Service.

Since June 18, Hollier said, infections have been found in Madison, Tensas, and East and West Carroll parishes.

He said the bacteria can spread either through seed corn or by being blown from place to place. “How it got here I don’t know,” he said.

It hasn’t shown up in Arkansas or Mississippi, but with infections so close it’s just a matter of time, said Jason Kelley, extension wheat and feed grains agronomist for the University of Arkansas System Division of Agriculture, and Tom Allen, a plant pathologist at Mississippi State University’s Delta Research and Extension Center in Stoneville, Miss.

Although several Mississippi farmers thought their corn was infected this year, lab tests didn’t bear it out, Allen said.

He noted that, just as many human diseases have flu-like symptoms, many diseases and problems — including drought stress — share the signs of Goss’s wilt.

And, oddly enough, pivot irrigation can leave a sheen that looks like bacterial exudate, Allen said. “There are several other things that could do something pretty similar,” he said.

Even when the disease is identified, there’s nothing much farmers can do to keep it from hurting their yield that season, he said.

Farmers whose corn has been infected by Goss’s wilt should bury the stalks and leaves left in the field to try to cut their chances of a widespread outbreak next year, Hollier said. Rotating out of corn into other crops could help, too, he said.

Hollier said many farmers are burning their fields after the harvest. Burning isn’t legal everywhere, and even those who burn the corn leaves and stalks should bury them afterward to speed decomposition, he said.

Weed control may also be important, because the bacteria can live in green foxtail, shatter cane and barnyard grass, he said.

 

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