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Mold, sprouting hiding in cornfields

Tom J. Bechman ear of corn showing signs of mold and kernel sprouting
UNWELCOME GUESTS: This ear, once embedded inside tight husks, is showing signs of mold and sprouting just prior to black layer.
Corn Watch: Check your fields for ear molds, sprouting and insect damage.

Dave Nanda found good news and bad news when he visited the Corn Watch ’22 field in central Indiana in early September. On the positive side, corn was nearing black layer.

“It wasn’t quite there, perhaps a week away,” Nanda says. “I could find brownish material at the tips of kernels, but it wasn’t black and sealed off yet. The crop wasn’t quite finished. However, it will finish in September, likely well ahead of any frost risk.”

Related: Why 2nd ears on stalk often fall short

There are two hybrids in the field, and both appear to be maturing at a similar pace, notes Nanda, director of genetics for Seed Genetics Direct. This seed company, headquartered in Jeffersonville, Ohio, sponsors Corn Watch ’22.

The second piece of positive news was that large, deep kernels were developing. This location received about 2 inches of total rainfall from June 1 until July 31. Since then, rainfall has totaled around 8 inches.

“It came back in time for grain fill, and temperatures also leveled out,” Nanda says. “The result are large, plump kernels, which will contribute nicely to yield.”

When Nanda checked the field in mid-August, it was still uncertain how many tip kernels might abort. Tip abortion can occur well up into grain fill if plants are stressed.

“With the return of adequate moisture, it appears fewer tip kernels were aborted than might have been otherwise,” he notes.

Flip side

Now for the negative news: Nanda checked yield at two locations, marking off 1/1,000 of an acre at each spot and counting ears. He also inspected ears. Based on his limited inspection, about 1 ear in 3 was already showing whitish to pinkish mold near the tip. Nanda tentatively identified it as Gibberella mold. While this type of mold doesn’t produce aflatoxin, it can produce vomitoxin, a potential issue if the corn is fed to livestock, particularly hogs.

“The ears were very upright, and the husks were tight,” Nanda says. “That, coupled with abundant moisture, likely set the stage for ear mold.”

That wasn’t the only potential problem Nanda discovered. On a few ears, he noticed that a few kernels were sprouting, still inside the husks. And a few ears showed signs of kernel damage within the portion of the ear covered by husks. He didn’t observe any live insects.

Dan Quinn, Purdue Extension corn specialist, has inspected ears in several plots and farm fields during September. He wasn’t finding mold early as Nanda did, but he did find ears with sprouts at the tip and signs of earworm feeding.

“Sometimes ears where the husks open up on the end are more prone to sprouting if it’s wet,” Quinn says. “As far as earworm, you may see the damage, but you may not see the worm itself.”

While Quinn hadn’t encountered moldy ears by press time, he acknowledged that earlier-season stress, primarily from drought, might increase the odds for opportunistic ear molds to appear. Stalk rots could also become a threat in fields that were stressed during the season.

Based on what he’s seen and Nanda’s report of mold in ears, Quinn advises checking corn still in the field carefully. You may want to consider harvesting fields with ear mold, sprouting or other issues as it makes economic sense to do so, based on corn grain moisture content.

TAGS: Crop Disease
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