Identification of Triazole Fungicide-Resistant Strains of Zymoseptoria Tritici and Parastagonospora Nodorum in Kentucky

Two different fungal pathogens cause the “leaf blotch disease complex” on wheat in Kentucky, which cause symptoms that often are indistinguishable to the naked eye. Parastagonospora nodorum (formerly known as Stagonospora nodorum) causes both Stagonospora leaf blotch and glume blotch, and Zymoseptoria tritici (formerly known as Septoria tritici) causes Septoria leaf blotch. In general, wheat farmers tend to manage both diseases primarily by spraying foliar fungicides. Most observations of these two diseases suggest that Septoria leaf blotch tends to be an early-season disease, that may be one of the first diseases to appear on the lowest leaves after greenup, whereas, Stagonospora leaf blotch tends to occur later in the season, at flag leaf emergence and after.