In the May 11 Wheat Disease Update, it was stated that yellow areas in a wheat field in Nuckolls County were due to nitrogen deficiency. The pattern of symptoms, however, suggests sulfur deficiency which is easily confused with nitrogen deficiency.

Sulfur deficiency is more common in soils that lack or have little organic matter, such as sandy soils or areas in fields such as slopes (Figure 1) that are prone to soil erosion, leading to little accumulation of organic matter. Therefore, symptoms of yellowing limited to certain areas in a wheat field are more typical of sulfur than nitrogen deficiency. In addition, symptoms of sulfur deficiency are more conspicuous when soil temperatures are cold as in early spring because there is less mineralization of organic matter (which releases plant available sulfur) in cold than in warm soils.

On individual plants, sulfur deficiency causes general yellowing and stunting of the entire plant, with yellowing more apparent on the younger leaves whereas with nitrogen deficiency yellowing is more apparent on older leaves. On older plants deficient in nitrogen, the lower leaves yellow and die whereas they remain pale green on plants deficient in sulfur. This is because nitrogen is redistributed to the younger leaves due to its mobility in the plant, resulting in severe yellowing on the lower leaves. On the other hand, sulfur is not as mobile and therefore symptoms of yellowing are milder on the lower leaves and more severe on the upper leaves. See the resources listed below that include information on management of sulfur deficiency.

Resources

Compendium of Wheat Diseases and Pests Third Edition. W.W. Bockus et al. (Eds). The American Phytopathological Society, 2010, St. Paul, MN.

Sulfur Deficiency Symptoms in Wheat. Farm Journal’s AgPro, 2011.

Sulfur Deficiency in Wheat. Randy Pryor, Nebraska Extension, Saline County, 2012.