Jack Frost is nipping at their ears

Bob Hensel displays the inside of a cob of corn he picked last week north of Princeton. Hensel said the dark yellow needs to come all the way to the base of each kernel before the corn is mature and ready for harvest. (BCR photo/Barb Kromphardt)

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Area farmers were relieved when a “Frost Advisory” was canceled Wednesday morning, but they’ve got a long way to go before they’re out of the woods.

A late spring planting season and a cool summer have combined to produce a corn crop that’s running considerably behind schedule this year. As of Monday, only 24 percent of Illinois’ corn crop was rated mature as opposed to an 84 percent average during the past five years. In addition, only 2 percent was harvested, a fraction of the 28 percent that’s usually been harvested by this time during the past five years.

“See that dark line there?” said Bob Hensel, breaking an ear of corn in two. “That should be clear to the bottom of the kernel. That’s got to be clear to the cob.”

Instead, the dark line in the corn, which Hensel picked just north of Princeton last week, was only about one-third of the way down the kernel.

According to Bob Frazee, University of Illinois Natural Resources Educator, physiological maturity is the term used to describe the point of grain development at which the kernels have maximum dry weight and the plant is safe from yield loss by frost. The formation of the black layer is the signal of full kernel maturity.

Once the black layer appears, the corn can no longer increase in weight and will begin a gradual reduction in moisture content during the drying period before harvest. Kernel moisture is usually around 30 to 35 percent at physiological maturity.

The Bureau County corn wasn’t anywhere close to that figure.

“If you took that right now, that is approximately 45 percent,” Hensel said. “It’s got miles to go.”

The cause of the problem was twofold. First was the rainy spring.

“April 16 was the first day you could get out there,” Hensel said.

Hensel, who farms in the rural Walnut area, was able to get out that day, and said that field is well-matured and safe from any frost. He planted another farm on May 7, and that farm is close to black layer, but a third farm wasn’t planted until May 11.

“A lot of it’s not a whole lot more mature than this,” he said, gesturing with the corn in his hand.

The other problem was the cool temperatures. July 2009 ranks as the coldest July in the statewide records with an average statewide high temperature of 70.4 degrees. Those temperatures slowed the maturity rate, and now that it’s October, it’s not getting any warmer.

“If we’d happen to get a frost sometime in the near future, we’d be in awfully bad trouble because this corn will weigh maybe 45 or 50 pounds to the bushel, and it would take quite a spell for it to mature enough to run it through a combine without chewing it up,” Hensel said.

Fully matured corn should weigh 55 to 60 pounds, but Hensel said immature corn weighs less because the unripe portion of each kernel is basically just dried milk.

So now it’s a race against the calendar. Hensel said the corn crop isn’t hurt yet, but the first serious frost will bring any additional maturing to an end. According to University of Illinois research, if a corn crop is prematurely killed 10 to 14 days before black-layer maturity, a 4 to 5 percent grain yield reduction can be expected. If the corn crop is killed three weeks before physiologically mature, the yield loss may approach 10 to 20 percent with considerable reduction in grain quality.

Corn harvest shouldn’t begin until physiological maturity, but Hensel said some producers won’t have a choice pretty soon.

“A lot of them are going to wait as long as they can, but some of them are going to get going because there’s some large farmers around that have a lot of work to do yet this fall,” he said.

For northern Illinois, the first frost usually occurs during the first week of October, and Hensel said he recorded last year’s first frost on Sept. 30.

“It wasn’t a great big killing frost, but we had frost,” he said.

And as for this year?

“It doesn’t look good,” he said. “It looks like it’s going to be an early winter, I would say.”

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