Wheat in many areas of central Kansas is at flag leaf emergence with many fields in the southeastern and south central region at the boot or heading stages of growth.
Monitoring over the past two weeks indicates that leaf rust, stripe rust, and septoria leaf blotch are all active in the state (Figure 1). In most situations, it appears these diseases are still at low levels giving growers some time to evaluate their situation and make final decisions about fungicide applications to help maintain the yield potential of the crop.
Figure 1. Current distribution of leaf and stripe rust on wheat in Kansas
The frequent rainfall and extended periods of high humidity this past week were very conducive for disease development. However, it may take several weeks for the infections occurring now to become visible as disease symptoms. Given the recent weather and the current distribution of disease, growers concerned about leaf rust, stripe rust, and other foliar diseases should be moving ahead with plans to apply fungicides. Growers still have time to gather more information from areas of the state where the diseases are not active and/or the wheat crop has not reached flag leaf emergence.
Erick DeWolf, Extension Plant Pathology