The risk of severe leaf diseases remains low throughout Kansas. My own scouting and reports from K-State agronomists indicate that leaf rust and stripe rust are not present in the state. Tan spot, septoria leaf blotch, and powdery mildew were absent in most fields; however, we did find a small number of fields with low levels of tan spot in Saline, McPherson, and Sedgwick counties. These fields all had wheat residue from previous crops on the soil surface. This residue is important because it often harbors the fungus that causes tan spot.
Drought stress was evident in most fields and the dry conditions are holding disease in check for now. Recent rains have brought some temporary relief to the dry conditions in a few areas of the state. We will continue monitoring the disease situation as this moisture may stimulate some disease. The symptoms of any new infections would not become evident for 7-10 days. The current risk of severe disease in Kansas and the need for foliar fungicides is low.
Summary of disease conditions in other states:
Texas has reported some stripe rust activity just south of Dallas but warm temperatures have slowed the progress of that disease. Bob Bowden, USDA Plant Pathologist, reports that leaf rust remains active in research plots near San Antonio, Texas. However, the disease remains at low levels in commercial fields according to Tom Isakeit, Extension Plant Pathologist for Texas A&M. Wheat fields in southern Texas are nearly ready for harvest. The trace levels of rust reported in central Texas have not advanced to cause problems in that area according to Ron French, Extension Plant Pathologist for Texas A&M. Rust has not spread into key wheat production areas of northern Texas.
In Oklahoma, Bob Hunger, Extension Plant Pathologist for OSU indicates that leaf rust and stripe rust have not been found in Oklahoma yet this season. Conditions remain dry in Oklahoma and they are currently evaluating fields for evidence of freeze injury that occurred on April 15.
Erick De Wolf, Extension Plant Pathology