Wheat has been covered with ice and snow for several weeks in much of Kansas. For the most part, the snow cover is welcome, says Jim Shroyer, Kansas State University Research and Extension crop production specialist. Snow provides protection from extremely low temperatures and will help topsoil moisture conditions when it melts.
Ice cover can also provide moisture and protection from the cold, but it can also be a potential problem for wheat, he says.
"Whether prolonged ice cover will damage wheat on a given field is hard to predict. Research has shown that damage is possible after 10 to 40 days of ice cover, depending on the physiological status of the wheat and the microclimate at the soil surface," Shroyer says.
Ice cover can cut off the oxygen supply to wheat, creating anaerobic respiration, he explained. The byproducts of anaerobic respiration, ethanol and carbon dioxide, and eventually kill the plants.
"Whether this actually occurs depends on a few key factors, such as the microclimate at the soil surface," says Shroyer. "If there was a layer of snow or loosely packed sleet, or even loosely packed crop residue, covering the wheat before the ice storm occurred, there may be enough trapped oxygen for the wheat to survive. On the other hand, if the wheat was covered by a solid sheet of ice with very few air pockets, the ice cover poses more of a threat."
If the wheat was dormant when it was covered by ice, it can remain healthy longer than if the wheat was actively growing at the time – possibly as long as 20 days or longer, depending on the microclimate conditions, he adds.
There is no way to predict with certainty how any given field of wheat will respond to the ice and snow this winter.
"Producers should not assume anything at this point, even if their wheat has been under ice for several weeks. The wheat may be fine, or the stand may be thinned. Some plants may lose part or all of their tillers. In the most severe cases, entire plants may die," Shroyer says.
Spring greenup will tell the story, he adds.
"If there are areas within a field that do not green up and start growing when
temperatures warm up in late winter or early spring, then producers should think back to what happened during December and January. If the problem area was under ice for several weeks, that could well be the cause of the problem," the crop specialist says.
If a field that had been under ice does not seem to be greening up normally, producers should proceed cautiously because the field may need to be replanted with a row crop.
"They should avoid applying any herbicides with a residual period that would prevent them from destroying the stand and planting a row crop this spring, if necessary," Shroyer says.