Yellow wheat caused by low temperatures
* Can the plants be pulled easily from the soil? If so, the root system is stunted and could be at least one cause of the yellowing.
* What herbicides had been applied to the previous crop? If atrazine had been applied to the previous crop, check on the rate used and the environmental conditions since the application. If soils have been drier than normal after the atrazine was applied, this would increase the chances for atrazine carryover into the wheat crop.
* What did the most recent soil test show? Are there nutrient deficiencies or lime requirements that haven’t yet been corrected?
* Is there a difference between early-planted and late-planted fields? Earlier planting usually results in bigger plants when going into winter, which can sometimes result in more cold temperature injury to the leaves over the winter. Later-planted wheat often has less root development going into winter, which can make the plants more susceptible to nitrogen and other nutrient deficiencies. Plants will grow out of the yellowing from either of these causes if growing conditions are good in late winter and early spring.
In the current situation, the likely cause of yellowing in most cases is cold temperature injury. I say that because: (1) the plants in most cases are showing yellowing or burning on upper leaves and leaf tips; (2) the symptoms are occurring over a wide region, especially in southern Kansas; (3) the symptoms are mostly on earlier-planted wheat with more leaf area exposed; and (4) the weather had been mild for much of December and January, and plants were green, followed by a period of cold temperatures recently.
Yellowing due to cold weather injury at this time of year is temporary, and should not cause any yield loss. Expect the wheat to return to a healthy green color when stem elongation begins if growing conditions are good -- unless another problem crops up.