Molds and Disease Plague Harvest So Far

What you see depends upon where you live.

Published on: Oct 13, 2009
"The pigeons come home to roost" is a popular phrase these days, particularly in politics. In corn and soybean fields in many parts of the state, it appears that the pigeons are coming home to roost. In other words, the effects of a cool, wet season are resulting in much higher levels of some disease problems than normal in both corn and soybeans. If you seed disease and insect damages, and if so, what king and how much you see, will likely depend upon where you're located within Indiana, and the weather patterns and localized diseased and insect pressures that existed in your area.

White old showed up early in northern Indiana. Traditionally more severe in narrow-row soybeans where less air moves inside the canopy, it's even showing up in some 30-inch rows soybeans this year. The disease is characterized by plants that retain their leaves after dying early. They're typically covered with a cottony, white growth. You'll also find black bodies, resembling rodent feces, on stems. Remedies are in the works from both better genetics and chemical treatments, but it is still a tricky disease to manage, and apparently much worse than normal this year.

Western bean cutworm has devastated some cornfields, especially in sandy ears in northwest Indiana. However, the pest, relatively new to Indiana, has now been identified in 14 Indiana counties, as it spreads to the west, notes John Obermeyer, a Purdue University entomologist. Keep your eyes out for this one. Normal triple-stack hybrids don't phase it. However, either Herculex or new Smart Stax hybrids with the Herculex trait included control it.

The outshoot after the worms leave are riddled ears, subject to all types of molds, from white to pink and all stages in between. Since shucks are compromised, water enters the ear, and some kernels sprout. Others are damaged so that part of the kernels appear to be overheated.

Now comes word that both gray and pink molds are showing up around the state. They are Diplodia and Gibberella ear rots. Charles Woloshuk, an Extension pathologist at Purdue University, says it's worse in the northeast and southeast. If it's in a field, typically anywhere from a few percent to 30% of all ears are infected.

Diplodia usually produces a grayish mold. Gibberella ear rot thrives by producing a pick to reddish mold, beginning at the tip and moving down the ear. It's easy to see on intact ears, but tougher to find in the bin.

Where GIB is involved, there is concern about a vomitoxin, injurious especially to swine. It's known as DON, for short. Diplodia doesn't have that capability, but feeding a high percentage of any type of molded grain is not recommended.

Keep your eyes open. This stretch of cool wet weather will make it worse, not better. Try to harvest these fields as soon as possible.