When temperatures dipped well below freezing the night of April 6-7, it may have caused moderate to significant damage to wheat in parts of Kansas (as well as Oklahoma and Texas), says Kansas State University Agronomist Jim Shroyer.

"Wheat that has either one or two joints can be injured by several hours of temperatures in the low 20s or lower," he says. "Even wheat that is not yet jointed will probably have some damage to the leaves, but this is just cosmetic injury that will not affect yields."
However, producers should not make any quick decisions about the condition of their wheat crop.

"It will take several days of warm weather following the freezes to evaluate the condition of the crop and its yield potential," says Shroyer. "Even if some of the main tillers are injured or killed, producers should wait to see if enough other tillers have survived to compensate for the lost yield potential."

If areas of a field lodge shortly after the freeze, that may indicate damage to the lower stems. "Producers should keep an eye on this wheat over the next week or so, and examine the lower stems," says Shroyer. "Damage may not be immediately evident. If there are darkened or water soaked lesions near the base of the stems, or if the stems are split, those tillers are damaged and will die.”

For more information read this .pdf.