Later Harvest, Greater Yield Loss

Growers waiting to harvest their corn most likely won’t see a significant decrease in grain moisture, but run the risk of increased stalk lodging, moldy ears, and yield losses the longer corn sits in the fields.

Peter Thomison, an Ohio State University Extension corn agronomist, said that unfavorable weather might be keeping growers out of their fields, but they should harvest as promptly as possible.

“We have a fantastic crop out there with yields averaging above 200 bushels per acre in many fields. Why let that crop go down the tube waiting on grain to dry down, which is questionable at this late date?” says Thomison, who also holds an appointment with the Ohio Agricultural Research and Development Center. “Right now in many areas we have a crop that is standing well, exhibiting good plant integrity with stalks looking good and intact ear shanks. But there’s only one direction that plant health is going to go and that’s down. Is a farmer willing to let those yields decrease or accept higher drying costs?”

Thomison points to research he and his colleagues conducted a few years ago, evaluating the state of corn hybrids the longer they stayed in the field. What the researchers found was that the longer corn was left in the field, the more yield loss was experienced — an average of 11 percent between mid-November and mid-December.

“The results of the research suggest that corn can tolerate a harvest delay until mid-November without major yield losses, but after that is when things start falling apart,” Thomison says. “After mid-November harvest delays begin to exact a toll on corn left standing in the field. In some years, our data showed yield losses as low as 5 percent, but in other cases it was as high as 24 percent ”

Thomison says that yield losses are closely associated with stalk lodging, especially with hybrids that are sensitive to stalk rots. Another major concern with leaving corn in the field too long is grain quality. Ears subjected to prolonged wet conditions can turn moldy, potentially contaminating grain with mycotoxins that are harmful to livestock.

“In extreme situations, kernels can start sprouting,” Thomison says, “which adversely affects marketability of the grain.”

According to the Ohio Agricultural Statistics Service, 76 percent of Ohio’s corn crop has been harvested, behind last year as well as the five-year average. Thomison says that farmers either can’t harvest their corn because of unfavorable field conditions or are waiting for the corn to dry down further.

“Perhaps the most striking finding about the research we conducted was that we didn’t see a significant decrease in grain moisture after mid-November," he says. "We saw grain moisture decrease 6.3 percent between mid-October and mid-December, but only 0.5 percent of that dry-down occurred after mid-November. If a grower is expecting to see a big jump in grain moisture change between now and mid-December, our studies would suggest otherwise. We even left corn in the field as late as March and didn’t see a drastic decrease in grain moisture.”

Thomison says that in recent years farmers have experienced good growing conditions that have allowed them to leave corn in the field longer than they probably should.

“But this is probably not the year to do be doing that,” Thomison says.

The last time growers faced delayed harvest issues on this scale was in 1992, when cool, wet conditions in the fall kept some growers out of their fields until that winter.
 

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