We are now several days past the severe freezes of March 24 thru 26 and one can clearly see damaged heads in area fields. In a broad and general sense fields which were in the later stages of jointing with the third node visible above ground (early planted, well developed fields), at the time of the freeze were significantly injured. Fields which may have been only in the mid-stages of jointing with only one or two node visible and well watered, thicker planted suffered little injury. However, I examined fields which were in this earlier stage of development, but a thinner stand and may have been very dry which did suffer some injury, up to about 30% of the main/older tillers. Even at 30% of these older tillers being damaged, there may be some compensation by other tillers in seed size and weight. The younger tillers will certainly be more numerous than these older, more developed tillers, and therefore the impact on yield will be less than it appears.
I have had questions about how to know if the head is damaged; in the photo above the left two heads have a very distinctive tan coloration, these are damaged. Compare this to the pearly-green color of a healthy head to the right in the image. To examine these tiny heads one must cut the stem lengthwise and carefully dissect the portion with the head. The head on the leaf in the photo above is about ¼ inch in length.
There is significant leaf injury in many fields. Leaf margins and leaf tips have turned yellow or brown by now, giving fields a tan tint as one looks out across the field. As long as the flag if is not significantly damaged, one should not anticipate a major impact on yield from leaf injury.
Additional tools to aid in that evaluation of wheat freeze injury include the publication “Wheat Growth” and “Freeze Injury on Wheat“.