The days are getting longer, and temperatures are finally warming after what seemed like a long winter season. As hopes for spring rise, many growers start looking at factors that could influence the yield potential of the Kansas wheat crop.
Recent research at Kansas State University shows how weather conditions in Texas appear to play a critical role in the development of regional outbreaks of the disease. Stripe rust often survives the winter in southern Texas, and wet conditions in this region increase the risk of stripe rust problems throughout the Great Plains. Moreover, dry conditions in this region often suppress the risk of outbreaks. The research documents how the timing of this moisture is also important with moisture levels the preceding fall (primarily October to December) and early spring (February) being most influential. Maps of soil moisture conditions in November when the crop is being established throughout the southern Great Plains can help illustrate these findings (Figure 1). The map for 2019 indicates a moderate risk of severe stripe this season.
Figure 1. Soil moisture levels in southern Texas when the wheat crop was established for the 2016-2019 growing seasons. In the low disease years, dry conditions (lightest green colors on the maps) dominate southern Texas. In years with severe stripe rust, moderate or high soil moisture conditions are prevalent in these same regions. These maps show soil moisture levels based on November “Palmer Z-Index” provided by NOAA-National Centers for Environmental Information.
This is consistent with observations from Dr. Amir Ibrahim and Dr. Clark Neely, researchers from Texas A&M University, who reported active stripe rust and leaf rust in Texas this year. The last report (March 18, 2019) indicated that stripe rust was slowing some with lesions caused by the fungus “drying up” in research plots just west of San Antonio. They noted that leaf rust was still very active at this same location. Let’s keep an eye on the disease situation and see what develops this year.
Erick De Wolf, Extension Plant Pathologist