COLUMBUS, Ohio - While some growers may choose to let corn dry in the field, the longer the corn sits, the greater potential it has for yield loss, according to a field crop expert with Ohio State University's College of Food, Agricultural, and Environmental Sciences.
In fact, delaying harvest beyond early to mid- November can result in yield losses from stalk lodging, ear drop and ear rot, said Peter Thomison, Ohio State University Extension agronomist. OSU Extension is the outreach arm of the college.
Letting corn dry in the field exposes the crop to unfavorable weather conditions as well as to wildlife damage, he said. Although delaying harvest has little to no effect on grain quality traits such as oil, protein, starch and kernel breakage, it may result in more moldy grain, Thomison said.
"The potential for bad things happening increases considerably as we delay harvest beyond Nov. 1," he said. "While unfavorable weather might have kept some growers out of their fields, they should harvest as soon as possible.
"If we get into a wet period, a lot of our corn can weather rapidly. The drying benefits we get from delays decrease considerably with very cool temperatures."
As of Oct. 27, 47 percent of Ohio corn had been harvested, compared to 62 percent that was harvested at the same time last year, according to the Ohio Agricultural Statistics Service. The five-year average for harvested corn during this period is 47 percent, the agency said.
Thomison said farmers likely haven't harvested their corn because of unfavorable field conditions or are waiting for the corn to dry down further.
But according to research he conducted evaluating the state of corn hybrids, the longer corn was left in the field, the more yield loss was experienced, with an average of 11 percent between mid-November and mid-December.
Thomison's study was conducted at three locations statewide over a three-year period. It looked at the effects of four plant populations, including 24,000, 30,000, 36,000, and 42,000 plants per acre, at three different harvest dates, including early to mid-October, November and December, on the agronomic performance of four hybrids in varying maturity and stalk quality.
The study found that:
* Nearly 90 percent of the yield loss associated with delayed corn harvest occurred when delays extended beyond mid-November.
* Grain moisture decreased nearly six percent between harvest dates in October and November. But delaying harvest after early to mid-November achieved almost no additional grain drying.
* The greatest increase in stalk rot incidence came between harvest dates in October and November. In contrast, stalk lodging increased the most after early to mid-November.
Some growers have experienced rain delays that have slowed their harvest, while others had planting delays earlier in the season, Thomison said.
"A crop with weak plant integrity is more vulnerable to yield losses from stalk lodging and ear drop when weathering conditions occur," he said. "The widespread root lodging that occurred as a result of wind storms in July is also contributing to plant integrity issues problem.
"We encourage growers to harvest now to lessen the impact of these weathering problems. A lot of people are letting corn dry in fields as long as it can, but we encourage people to harvest promptly because we typically don't see significant decreases in grain moisture after early to mid-November."