By MARK BUTZOW
VINCENNES, Ind. — An Arctic blast hit the heart of the soft-red winter Wheat Belt last week, putting the dormant crop at risk of winterkill damage in some areas.
Most of the northern Midwest wheat crop was protected from frigid temperatures by snow cover; however, there was a strip across the central United States without snow accumulation mid-week, leaving dormant wheat exposed to winterkill.
Most susceptible were central Missouri, central Illinois, central Indiana and the central and southwestern parts of Ohio, according to weather experts from Radiant Solutions.
On Jan. 30, wind chills dipped to -7 degrees Fahrenheit in Columbia, Mo., -17 in Quincy, Ill., -16 in Springfield, -30 in Kokomo, Ind., and -15 in Dayton, Ohio, according to National Weather Service observations. Air temperatures rose slightly Thursday, but wind speeds were higher, resulting in even lower wind chills – for example, Quincy recorded -22 wind chills and Dayton’s “feels like” number dropped to -20 degrees.
Temperatures were even colder mid-week in the northern Midwest, with lows dropping to -35 in places, but the snow cover was deep enough to prevent crop damage.
Wheat-growing areas to the south, which is a big soft-red wheat country, didn’t get as cold but still may see some reduced stand counts when dormancy breaks.
“We escaped the worst of the cold here in southern Indiana,” said Purdue University extension small grains expert Chuck Mansfield, based in Vincennes. “Soft-red winter wheat varieties adapted to our area are usually winter-hardy down to -5 to -10 Fahrenheit.
“Outside of a few pockets, I don't think it got quite that cold here, at least not for very long. So, we should be good as far as plant survival. We'll probably see superficial tissue injury.”
Unprotected wheat can experience winterkill if temperatures dip below zero for four hours or more, but damage is more likely after an extremely dry autumn such as the Plains and Midwest experienced before last winter. Planting in hard, dry soil might mean the now-dormant crowns were not deep enough, and a lack of rain before the crop goes dormant can retard the growth of secondary roots and tillers.
Those conditions in late 2017 and a deep freeze the first week of January 2018 likely did some damage to last year’s hard-red and soft-red wheat. This year, the odds are there will be less impact on yield, especially since warmer temperatures returned quickly.
“It will probably burn back a little bit of that growth,” said Carl Schwinke, vice president of grain supply for Siemer Milling Co. in Teutopolis, Ill. “There’s no way to know until they do stand counts and see.”
Another factor to consider is fall temperatures. The cold-hardiness of wheat plants is related to how long ground temperatures are below 50 degrees before the wheat seedlings go dormant for the winter, so an autumn that is too warm – or swings between warm and cold spells – could limit seedlings’ acclimation to the cold.
“The process of cold acclimation within a sufficiently developed wheat seedling begins when soil temperatures at crown depth fall below about 50 degrees Fahrenheit,” Kansas State University wheat and forages specialist Romulo Lollato wrote in 2015. “It takes about 4-6 weeks of soil temperatures below 50 degrees at the depth of the crown for winter wheat to fully cold harden.
“The colder the soil at the depth of the crown, the more quickly the plants will develop winter-hardiness.”