Maturity becomes a concern as harvest approaches

AMES, Iowa – Prepare for a long harvest season.

Planting delays in Iowa last spring could prevent a significant portion of this year’s corn crop from maturing on time, said Iowa State University agriculture experts. That means farmers may still have corn to harvest deep into November as they attempt to give their corn fields as much time to dry down as possible.

An early freeze could stop a portion of the corn crop from reaching maturity, and farmers will watch temperatures closely in the coming weeks, the ISU experts said.

Farmers across the state struggled to get their crops planted last spring due to cold and wet weather, said Mark Licht, an assistant professor of agronomy. Iowa farmers made the most of a few short stretches in April and May during which field conditions improved enough to plant their crops, but around 20% of Iowa’s corn crop was planted after June 2, Licht said. Soybeans, which require a shorter growing season than corn, largely have caught up this summer, but much of Iowa’s corn crop remains about two weeks behind an average year, Licht said.

“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.

Dennis Todey, director of the U.S. Department of Agriculture’s Midwest Climate Hub, said it’s likely some percentage of Iowa’s corn will not reach proper maturity by the time farmers have to harvest their crops, but it remains to be seen how big of a percentage that will be. Warm temperatures the next few weeks could accelerate maturation for much of the corn in question, Todey said, but extended forecasts are predicting slightly lower temperatures than average in early September.
Todey said when the first freeze occurs also could impact the maturation of this year’s corn crop. A hard freeze during which temperatures fall below 28 degrees Fahrenheit essentially shuts the plants down and prevents them from maturing any further. Northern counties in Iowa usually experience the first freeze in early October, while southern counties typically experience the initial freeze later, often around the third week of October. A particularly early freeze could prevent a significant portion of Iowa’s corn crop from reaching maturity, Todey said.

Sotirios Archontoulis, an associate professor of agronomy, said the slow spring planting and prevailing cool weather could affect the quality of the corn crop, even in fields that reach full maturity. The delay in the start of the grain-fill period by two weeks this year means the 2019 crop experienced less daylight and soaked up less solar radiation, which drives photosynthesis and yield. That can lead to suboptimal growth in the plants, causing small kernels and lower test weight, even if overall yields look good, Archontoulis said.

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