CHICAGO, March 21 (Reuters) – A cold snap this weekend likely hurt hard red winter wheat in a portion of the southern U.S. Plains, but the extent of any damage will not be known for several days or more, meteorologists and crop experts said on Monday.
Temperatures dropped into the teens Fahrenheit (minus 10.5 to minus 7.2 Celsius) in portions of the Plains for several hours on Saturday and Sunday, colder than forecasters had expected.
“We didn’t have any models that were showing anything so cold,” said Joel Widenor, a meteorologist with the Commodity Weather Group.
Wheat was most vulnerable to damage in about 20 percent of the HRW belt, he said, including southwest Kansas, southeast Colorado, and the “panhandle” region of western Oklahoma. Dry conditions have also been building in this region.
Wheat sheds its ability to withstand cold as it develops in the spring, and warm weather in early March had bolstered spring growth.
The U.S. Department of Agriculture said 10 percent of the Oklahoma winter wheat crop and six percent of the Kansas crop by March 13 had reached the “jointing” stage of growth, when it can be harmed by temperatures falling to 24 degrees Fahrenheit or below, for two hours or more.
“Anywhere that was solidly into the jointing period, there would have been some damage,” Widenor said.
A sharp warm-up is under way in the region, with highs expected Monday near 80 F (27 C) in southwest Kansas, and the change may help expose any freeze injury.
“Symptoms may start to appear later this week and will likely be clearly identifiable by the end of this week … Damaged wheat heads will be bleached, yellow, or brown and will easily break when pushed against,” Jeff Edwards, an Oklahoma State University agronomist, said on Monday in a blog post.
Winter wheat plants still have time to recover by producing new tillers, or stems, that could produce grain, limiting yield loss.
“It’s early enough for damaged tillers to be replaced with new ones,” said Arlan Suderman, chief commodities economist with INTL FCStone, “but dryness may prevent that from happening.”
The USDA released updated crop progress and condition ratings after the market closed.
The wheat crop condition as of Sunday in Kansas was almost unchanged.
Winter wheat condition rated one percent very poor (one percent last week), six percent poor (six percent last week), 36 fair (37 last week), 51 good (50 last week) and six excellent (six percent last week.
As of Sunday winter wheat jointed was 20 percent, ahead of three percent last year and the five-year average of seven percent.
In Oklahoma the winter wheat crop was one percent very poor, two percent poor, 34 percent fair, 52 percent good and 11 percent excellent.
Winter wheat jointing reached 38 percent, up five points from the previous year and unchanged from normal.
