sealPurdue News

October 1999

Curious corn problem puzzles Purdue experts

WEST LAFAYETTE, Ind. – Purdue University corn specialist Bob Nielsen have been getting a rash of reports about an odd grain-filling problem that he and Purdue Plant and Pest Diagnostic Laboratory director Peggy Sellers are calling translucent kernel syndrome.

"The initial symptoms of this oddity are the appearance of plump, translucent, liquid-filled kernels scattered randomly among already-dented kernels throughout an otherwise normal-looking ear," Nielsen says. "The abnormal kernels subsequently shrivel dramatically as the kernel matures, resulting in a shriveled kernel appearance not unlike mature sweet corn kernels."

Nielsen and Sellers say that as many as half an ear's kernels can be affected by the oddity. But they add that the number of plants affected in a field is more difficult to determine. Usually when the syndrome is seen in one ear, it is found throughout a field.

So far this year, the phenomenon has been reported mainly in northwest Indiana. "Initially, there appeared to be a common planting date link of the first week of May," Nielsen says, "but subsequent reports have indicated a wider range of planting dates. There is some evidence of a common corn inbred link, but we are still investigating that detail." Beyond those, there are few other common threads that connect the reports.

Nielsen says it's tempting to conclude at first glance that these kernels have aborted due to excessive heat or drought conditions that occurred shortly after pollination. And he points out that, in fact, typical kernel abortion symptoms are showing up in fields throughout Indiana this year.

"However," he says, "the pattern of typical kernel abortion usually involves those kernels at the tip end of the cob and rarely includes a random scattering of aborted kernels throughout the ear."

He also says that kernel abortion typically happens during the blister and early milk stages – not grain fill – and usually results in very small, shriveled kernels.

Nielsen and Sellers say that ears they've seen have not exhibited significant kernel abortion at the ear tips. Additionally, the shriveled kernels are nearly full size, not the usual small, aborted size, and the cobs are normal in size and do not show any other stress symptoms. Plants in the affected fields also appear normal.

Another initial reaction to the random pattern of affected kernels is to blame Fusarium infection, Nielsen and Sellers say. But tests done by Purdue's Plant and Pest Diagnostic lab have shown Fusarium in some – but not all – of the symptomatic kernels. Sellers and her colleague in the lab, Gail Ruhl, say that these results indicate that Fusarium likely is not the main cause of the translucent kernels.

CONTACTS: Nielsen, (765) 494-4802,; Sellars and Ruhl, (765) 494-7071

Compiled by Chris Sigurdson, (765) 494-8415,

Purdue News Service: (765) 494-2096;

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