Unusually mild and wet conditions in December and early January caused wheat to green up and created concern about whether the wheat is more susceptible to cold injury if temperatures were to drop sharply, said Jim Shroyer, K-State Research and Extension crop production specialist. For now, at least, there is no reason for concern.
"Although the wheat is green, and may even have been growing a bit in the more southern areas of Kansas during December and early January, that does not mean it will have lost all of its winter hardiness," Shroyer said. "As long as nighttime temperatures are below freezing most days, wheat will retain a sufficient level of winter hardiness."
An occasional period of one to three days where nighttime temperatures do not get below freezing will not cause significant loss of winter hardiness, he said. It is when nighttime temperatures consistently stay above freezing for a week or so that there may be some loss of winter hardiness.
The process of gaining and losing winter hardiness in winter wheat is a gradual one, he said.
Temperatures fluctuate most years as winter begins and ends, and wheat's winter hardiness tends to ratchet up and down with the temperatures. After a warm spell in winter, wheat will lose some winter hardiness – but it will regain it as temperatures get cold again, he added.
"Every time this happens, however, the wheat will lose some winter hardiness. The peak level of winter hardiness in wheat occurs when temperatures get cold and stay cold all winter. Wheat that greens up and then goes back into dormancy will not have quite the same level of winter hardiness as wheat that remains dormant all winter," he said.
The bigger concern for wheat in general is that subsoils are still dry in most areas of Kansas, Shroyer said.
December rainfall in most areas of Kansas helped improve topsoil moisture conditions, and there is more reason for optimism about this year's wheat crop than there was at planting time, he said. But subsoils remain dry, which could be a problem later this spring.
"Wheat conditions have improved, but we're not out of the woods yet," he said.