April 18, 2007 | By: Laura Skillman

The recent cold snap damaged early-planted corn that had emerged and, by lowering the soil temperature, delayed emergence of other planted fields. As a result, farmers will have to replant some acres.

While the freeze is costly for farmers facing replanting, this year’s corn crop can still be planted in a timely, efficient manner. Prior to the cold snap, an estimated 26 percent of Kentucky’s 1.31 million acres of corn was planted. It’s unclear how much of that was damaged and needs to be replanted.

Generally in a single freeze event, the growing point of young corn plants is protected beneath the surface, said Jim Herbek, grains crop specialist with the University of Kentucky College of Agriculture.

“However, on this go-around we had at least three nights in a row of temperatures in the low 20s. This was something different than usually occurs so we were expecting more damage, and it looks like there is quite a bit,” he said. “Three nights in a row allowed the ground-level temperatures to drop tremendously and damage the growing point.”

It’s been more than a week since the freeze damage occurred, so farmers should be able to tell if their corn survived. To make the determination, Herbek said farmers should dig some up, and if the growing point is yellowish white and firm it should be OK. If the growing point is brown and mushy or rotted, it is gone because the growing point is dead and won’t come back.

Corn that had not emerged before the freeze should be OK. He noted that emerged corn planted shallow (1 inch or less) is more damaged than those planted 1.5 to 2 inches. 

For those needing to replant, finding additional seed may be a challenge because of the large corn crop expected to be planted across the country this year. An additional 190,000 acres of corn is expected to be planted in Kentucky this year compared to 2006.

But there’s still time for farmers to plant Kentucky’s corn crop in a timely manner and have good yields. Planting date plays an important role in yield potential, but it is only one player in the crop’s final outcome. Management practices, such as pest control and fertility, as well as weather conditions throughout the growing season also play important roles in determining final yields.

“In western Kentucky, if we can get the corn planted by at least the first few days of May, we should be OK in terms of yield potential,” Herbek said. 

Results of a six-year study conducted by UK College of Agriculture scientists determined that Kentucky farmers have an optimum window for planting that varies somewhat across the state.

Over the long term, planting between April 10 and April 30 should achieve the best results. To avoid substantial yield losses, farmers in far west Kentucky should be finished by May 1; in west-central Kentucky by May 5 to May 10 and in eastern Kentucky by May 10 to May 15. While these windows rapidly are closing, the equipment most farmers have today should enable them to make rapid progress once they return to the fields.

Farmers who are opting to destroy their freeze-damaged wheat crop and to plant corn need to be aware of certain label restrictions on chemicals that have been applied to wheat. Be sure to read and follow the label directions when making any replanting decisions. Producers also can assume about 50 percent of the nitrogen they applied to their wheat will be available to corn.

Additionally, farmers who decide to switch to soybeans in their damaged corn fields need to be aware of certain label restrictions as well, if chemicals have already been applied to the corn, and to follow label directions.


Jim Herbek, 270-365-7541, ext. 205