Corn showed resilience to cold temps

May 26, 2020

The temperature dropped to 27 degrees early Saturday morning, May 9, in the area where the Corn Watch ’20 field is located. The Corn Watch ’20 field wasn’t planted yet, but the same operator did have other fields planted. In fact, the Corn Watch ’20 crew began flagging when plants emerged on one of the operator’s fields, which was planted on April 20. It was a trial run for doing the same thing on the Corn Watch ’20 plot later. Plants which emerged the same day were marked with a flag of a specific color.

The first plants emerged 14 days after planting and the last ones emerged 21 days after planting. The freeze occurred at day 20, when most plants had broken the surface. Since it had been cool and wet, most were yellow to pale-green and they hadn’t yet unfurled.

The freeze may have affected their color somewhat, but 10 days later, it was obvious they were on their way to becoming full-fledged corn plants.

“We saw a few with some curled leaves here and there in the field, but it looks like about a 95 percent stand,” the operator observed on May 19. “It’s definitely a keeper.”

Dave Nanda, director of genetics for Seed Genetics Direct, which sponsors Corn Watch ’20, isn’t surprised that the plants survived.

“As long as the growing point below ground didn’t freeze, we knew plants would recover,” Nanda said. “The growing point is the key.”

When the freeze was predicted but had not yet occurred, Bob Nielsen, Purdue University Extension corn specialist, noted that the key would be the growing point — it might be possible for a 28-degree freeze lasting up to two hours to kill the growing point below the soil surface. It would be more likely to occur if the soil was dry.

However, based on Nielsen’s observations several days after the freeze, it appeared that in most cases, the growing point below the surface wasn’t affected. Even with corn plants which were larger, and which had leaves unfurled, the leaves may have been frosted away, but the plant remained alive.

“It’s always important to wait three-to-five days to see if corn will recover after damage caused by an event like a frost, freeze or hail,” Nielsen noted. “You may need to wait longer if it is cool after the event, which it was in this case. However, within a few days, there was evidence of regrowth in most fields.”

The Corn Watch ’20 field was planted on May 13, after the freeze. By then, temperatures warmed up considerably, although there were still some days with the high temp hitting below normal. Early indications are that the later-planted corn is emerging faster than the corn planted April 20.

Emergence day-by-day will be flagged in the Corn Watch field as well. In fact, there are two hybrids planted in the field and the goal is to track emergence for both. Look for these reports soon.

The Corn Watch ’20 field is sponsored by Seed Genetics Direct. Reports on the field’s progress are provided all season (#CornWatch20); read the latest Corn Watch ’20 articles here. Stories are written by Tom Bechman.