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From staff reports
Recent cool temperatures in Western Nebraska have farmers worried about what will happen to the wheat. Winter wheat in that growing region is in the late boot to early heading stage, but with the abnormally cool weather, University of Nebraska extension agents are encouraging producers to scout fields for damages that could lead to yield reductions. Injury to wheat can occur not only by the low temperatures but also by the duration of low temperatures. Once the wheat is headed, producers should be able to see injury. It is recommended that producers split a plant lengthwise with a sharp knife. If the color is white or brown, there is most likely freeze damage. Uninjured plants are bright yellow-green. In addition, frozen damaged wheat may have none to small tillers, nodes and/or twisted leaves. Wheat with leaf damage can still produce new tillers and leaves regrow with warmer weather. Stem injury could cause plants falling over or lodging, which, if at near maturity, can mean decreased yield and harvest slow down with wind and hard rain.
If the head is not exposed, wheat may not be as affected as the microclimate in the wheat canopy may not be as low as it is above ground and as a matter of fact the microclimate of the crop may be warmer, which helps protect the wheat underground. According to a press release from UNL, if topsoil moisture is good, it helps to protect wheat against temperature changes versus dry soil.
As for freeze injury, extension points out that the wheat has to be subjected to freeze for over two hours before it hampers growth if it is in the growth stage and the extent of freeze damage is also based on field elevation. For more information, go to: https://cropwatch.unl.edu/assessing-freeze-injury-wheat