By Jennifer Stewart
May 10, 2012
A late-April freeze damaged some of northern Indiana's early progressing winter wheat crop, leaving growers to decide whether to let the crop yield or tear it up altogether.
While most of the crop survived near-freezing nighttime temperatures in April, it was the last freeze of the month that occurred while wheat was close to heading that caused the most damage.
"Indiana has experienced several weeks of cooler weather and nights that were near freezing in mid-April. Fortunately, most of our wheat was jointing at this time and the damage was only leaf tip burn," said Shaun Casteel, Purdue Extension agronomist. "We thought we were out of the woods, then temperatures on April 26 dipped below freezing again. Hard freezes were noted in many areas in the northern third of the state, so wheat fields should be scouted now."
The most severe freeze damage to wheat comes when the crop is in growth stages between boot and flowering. The crop was in the boot to heading stages when the last freeze hit - prime time for problems.
According to Casteel, that means growers need to be out in the fields getting a close look at the condition of their crops. Scouting from the driver's seat won't be enough.
"Windshield scouting is not suggested because many of the flag leaves were not burned with the recent freeze, so a drive-by will not always show the effects of the damage from the road," he said. "Younger wheat, prior to boot, will need to be split to determine if the growing point is dead. The leaves may still be green, but the developing head is dead."
If the growing point, or developing head, is dead it will be brown to black. If the emerged and emerging heads are white, the tissue is dead. Pale green portions of the head, however, are what Casteel calls "questionable" and will need to be monitored a little bit longer.
Growers who scout and find damage have a few options. Because crop development is so far ahead of schedule, Casteel said fields with marginal damage could be left to yield, and there still should be an opportunity to plant a second crop.
"Wheat is advanced for the time of year, and assuming harvest will be earlier, there will be greater opportunities for double-cropping soybeans further north than I typically recommend," he said.
Severely damaged fields could be cut for hay or wheatlage, or the crop could be mowed down, tilled up or killed with herbicides. Then, corn or soybeans could be planted in its place.
"It is early May, and we have plenty of time to establish a good crop of soybeans or corn in these fields," Casteel said. "The main point is to provide the best opportunity to establish a good stand and not rush into planting into wheat stubble or a mat of wheat residue without the proper planting equipment."
More information about winter wheat freeze damage, as well as using the crop as a forage, can be found in the May 4 issue of Purdue Extension's Pest and Crop Newsletter at http://extension.entm.purdue.edu/pestcrop/2012/issue6/index.html