Nation & World

Early hard freeze could reduce corn crop

Late planting will require more warm weather

Corn dries in the field in southwest Cedar Rapids. (Liz Martin/The Gazette)
Corn dries in the field in southwest Cedar Rapids. (Liz Martin/The Gazette)

Iowa farmers are hoping the first hard freeze will occur later than normal this fall, allowing more time for the state’s corn crop to reach maturity.

Almost 20 percent of Iowa’s corn crop was planted after June 2 as farmers struggled with cold and wet weather in the spring. That means farmers still may have corn to harvest deep into November as they attempt to give their cornfields as much time to dry as possible.

Mark Licht, an assistant professor of agronomy. at Iowa State University, said farmers made the most of a few short stretches in April and May during which field conditions improved enough to plant their crops.

“Things are so delayed that unless we have a very late first freeze, some crops will be damaged somewhat this year for harvest,” Licht said.

A hard freeze with temperatures falling below 28 degrees essentially shuts the corn plants down and prevents them from maturing any further.

Northern Iowa counties usually experience the first freeze in early October, while southern counties typically experience the initial freeze later, often around the third week of October.

Soybeans, which require a shorter growing season than corn, have caught up this summer for the most part. But much of Iowa’s corn crop remains about two weeks behind an average year, Licht said.

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Dennis Todey, director of the U.S. Department of Agriculture’s Midwest Climate Hub, said warm temperatures over the next few weeks could accelerate maturation for much of the late-planted corn. Extended forecasts, however, are predicting slightly lower-than-average temperatures in early September.

The late spring planting and cooler-than-normal weather also could affect the quality of the corn crop that will be fully mature, according to Sotirios Archontoulis, an associate professor of agronomy at ISU.

He said the delay in the start of the grain-fill period by two weeks means the 2019 has crop received less daylight and soaked up less solar radiation, which drives photosynthesis and yield.

That can lead to smaller kernels and lower test weight. Higher-than-normal moisture content also will require more drying with propane before the crop can be stored in a grain bin.

“We’re two weeks behind with cool weather on the way,” Archontoulis said. “There’s some concern growing.”

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