Weather's effect on winter wheat

By: Dave Pike and Drake Robards

 
 

The winter is certainly not over, but there are already some concerns about the survival of winter wheat. As our staff meteorologist, Eric Snograss, mentioned in his January 9th weather video, the average temperature for the weekend across the United States was 11 degrees Fahrenheit. Wheat growers must start thinking soon about the possibility of replacing severely damaged stands. 

Winter wheat survival through winter depends on several factors including crown depth in the soil and time of planting. Shallow seed depth can put the growing point near the soil surface where repetitive warming and cooling of the soil can have negative effects on cell components. A rough soil surface or planting in loose soil exacerbates the warming and cooling, and compounds the problem for a shallow seeded crop. 

Additionally, if wheat is planted late in the fall, there is little chance for the wheat to be tillered. Wheat with two or more tillers is more hardy than smaller plants. A big factor is the variety of wheat selected as some are much better than others in surviving adverse winters. 

Although exposed wheat plants can survive temperatures of -5 to -10 F, it is often not the cold temperature by itself that kills or injures wheat. Perhaps the most damaging weather factor is an extended period of favorable temperatures followed by a rapid onset of very cold weather. Temperatures which gradually get colder give the plant an opportunity to adjust, which promotes winter hardiness. 

Other weather factors are those that result in a dry soil. Wet soils lose and gain heat slower, and therefore are more resistant to the damaging temperature changes. The dehydration of the growing point of wheat from a combination of cold temps and dry soils is often the culprit in winter kill and injury. 

Of course, snow is a good insulator, and when covering the soil at depths of 3 to 5 inches will moderate temperature changes at the soil surface and keep the soil surface moist. This will decrease the impact of cold weather on wheat dehydration and death. 

So what effect will the recent widespread ice storm have had on the wheat crop? The majority of the wheat in the Midwest was dormant at the time of the storm, so it is unlikely there will be much damage from the ice. It is also doubtful that the ice persisted long enough to cause harm to actively growing wheat, except in some of the worst hit locations. 

While it's too early to tell if your crop has been damaged beyond saving, scouting the crop will be a priority when the crop greens-up. Watch for plants that fail to produce a green leaf, and look for large spots where growing plants are unlikely to "fill-in" for ones that have failed to survive the winter.