Efficacy of common azoles and mefentrifluconazole against septoria, brown rust and yellow rust in wheat across Europe

Septoria tritici blotch – STB (Zymoseptoria tritici) is the most serious leaf disease of wheat in Northern Europe. Problems with fungicide resistance in the populations of Z. tritici have caused concerns for future control options. During two seasons (2017 and 2018), a common protocol was applied for testing the field performance of six azoles across Europe, including a new azole, mefentrifluconazole. In total, 26 trials were carried out in 11 countries with a focus on the control of STB. As has previously been reported, the control level of STB from currently registered azoles in different countries has been reducing but is also highly variable across Europe. This variation is linked to intensity of use and the specific azole resistance situation in the Z. tritici population. The new azole mefentrifluconazole performed superior compared to currently authorised azoles for control of STB.