Septoria tritici blotch (STB; Zymoseptoria tritici) is the most important leaf disease of wheat in Northern and Western Europe. The problem of fungicide resistance in Z. tritici populations is challenging future control options. In order to investigate differences in azole performances against STB, 55 field trials were carried out during four seasons (2015-2018). These trials were undertaken in ten different countries across Europe covering a diversity of climatic zones and agricultural practices. During all four seasons, four single azoles (epoxiconazole, prothioconazole, tebuconazole and metconazole) were tested. Increasing variability in the performances of these azoles against STB was observed across Europe. The efficacy of the tested azoles varied considerably across the continent and between countries. The shifts in disease control from these commonly used azoles were confirmed by increasing EC 50 values for epoxiconazole, prothioconazole-desthio and metconazole. The sensitivity towards tebuconazole remained relatively low across the four years. The frequencies of CYP51 mutations varied substantially across Europe, with a clear pattern of significantly decreasing frequencies of D134G, V136A and S524T in the local Z. tritici populations from west to east. In contrast, no major differences were seen for CYP51 mutations V136C, A379 and I381V. The four azoles showed different levels of cross-resistance, which again depended on specific CYP51 mutations. Across the four seasons, the single azoles increased the yields between 9 and 11% on average.

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BACKGROUND The aim was to determine the influence of harvesting time and meteorological conditions on the occurrence of Fusarium spp. and mycotoxins in the grain of spring cereals. A field experiment was performed in 2016–2018 with spring oat (Avena sativa L.) and spring triticale (× Triticosecale Wittm.) plots. Grain samples of oat and triticale were analysed for Fusarium infection and co‐contamination with mycotoxins deoxynivalenol (DON), zearalenone (ZEA) and T‐2 toxin (T‐2). RESULTS Results from the three‐year study showed that the occurrence of Fusarium spp. fungi and mycotoxins produced by them in spring oat and triticale grain was most influenced by the meteorological conditions at harvesting time and crop species. CONCLUSIONS It was found that in all experimental years, F. poae, F. tricinctum and F. sporotrichioides predominated in oat grains and F. graminearum, F. sporotrichioides and F. avenaceum predominated in spring triticale; as a result, oat grains were more contaminated with T‐2 and triticale grains with DON and ZEA. Due to the rainy harvesting period in 2017, the contamination level of Fusarium fungi of grain of both crop species was 100%, and the concentrations of DON and ZEA in the samples of spring triticale were several times higher than those set forth in the EU regulation. Co‐occurrence of all three mycotoxins analysed (DON, ZEA and T‐2) was identified in these samples. © 2020 Society of Chemical Industry

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