Unusually cool summer temps slowing corn development

Cooler-than-normal summer temperatures are slowing corn development across Ohio, and harvest could be delayed if the weather trend continues throughout the growing season.

Peter Thomison, an Ohio State University Extension agronomist, said corn planted in late April or early May would normally be tasseling and silking by now, but because of the cooler temperatures, many cornfields have not reached these growth stages yet.

“We haven’t seen much silking yet, and in some areas, the corn is shorter than normal,” Thomison said. “What we’re looking at is the cool weather causing the slow development and shorter plant height.

“When you have cool weather, cells don’t grow as big so the internodes are shorter and plants are shorter in height. Lack of soil moisture is also contributing to smaller plants in areas short on rain.”

Only 33 percent of the corn crop is silking, which is slightly higher than last year at this time, but behind the five-year average by 17 percent, according to the Ohio Agricultural Statistics Service July 19 report. The report showed there were 119 growing degree days, 47 days below normal.

In addition to the cooler temperatures, a lack of adequate rainfall in some areas of the state is also taking its toll on the crop, but things could be worse, Thomison said.

“There is tremendous variation across the state,” he said. “Areas that have been getting rain, combined with moderate temperatures, have ideal growing conditions for corn.

“In areas lacking rain, the low temperatures are helping limit water stress. Otherwise we would probably be confronted with major drought damage from the lack of rain.”

Cool temperatures have benefits for the corn crop during the upcoming grain-fill period. Thomison said that cooler temperatures slow respiration, contributing to better grain fill, a lengthier grain fill period and potentially higher yields. Cooler temperatures also inhibit disease and insect development.

However, cooler temperatures throughout the growing season could delay harvest.

“The situation reminds many of the 1992 corn crop, when we had phenomenal yields, but we also had corn harvested in January because it was too wet during the fall to enter the fields,” Thomison said. The average state corn yield that year was 143 bushels per acre, the highest acreage recorded to date at that time.

Despite the cooler temperatures, the crop still needs adequate moisture. According to the Ohio Agricultural Statistics Service, as of July 19, rainfall averaged 0.27 inches, 0.53 inches below normal. Topsoil moisture was rated 58 percent short to very short.

“Right now farmers are looking at when the next rain will come,” Thomison said. "Despite the current rains we've had over the last day or two, we still need more."

Corn is reported to be 74 percent in good to excellent condition.

Corn is Ohio's most valuable field crop commodity. According to the Ohio Department of Agriculture, corn production contributes $2.1 billion to agriculture. Feed grain serves as a main component of corn production, but the crop is also becoming an integral source for ethanol.

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