Last week’s cold temperatures will long be remembered, especially the ice-covered highways. But crops may have been damaged as well.
Preliminary reports indicate that crops responded differently, as some canola that was in bloom could have been damaged, and some spring safflower is showing damage. Wheat for the most part is subjected to adverse weather conditions during much of its annual growing period. However, the abnormally cold temperatures of last week are not normal. Wheat in the tillering stage will begin to be injured when temperatures remain around 12 degrees Fahrenheit for more than two hours.
Freeze damage symptoms include leaf chlorosis, leaf tip burn, silage odor, and a blue cast to fields. This damage will result in slight to moderate yield reductions.
If wheat was to the jointing stage (the beginning of the reproductive stage with hollow stem at base of plant), which usually does not occur until March, the cold temperatures would have a more significant impact. In fact, at the jointing stage, temperatures of 24 degrees Fahrenheit for more than two hours can result in moderate to severe yield reductions.
Symptoms of freeze injury at this stage will include death of growing points, leaf yellowing, lesions, splitting or bending of lower stem and odor.