Zymoseptoria tritici causes septoria tritici blotch (STB), the predominant fungal disease in wheat in Denmark and Sweden. Disease control is highly reliant on fungicides in the group of demethylation inhibitors (DMI). The use of DMIs has increased steadily since their introduction in the 1970s. Epoxiconazole and prothioconazole were the most widely used active ingredients in the last ten years. The goal of this investigation was to survey the resistance development of Z. tritici towards these two compounds. In total, EC₅₀ values were determined for 3472 Z. tritici isolates from 2012 to 2019. Also, the field performance of the most used DMI compounds was tested in field trials. EC₅₀ values of epoxiconazole and prothioconazole increased in the testing period. A significant shift was observed for epoxiconazole in 2016 and again 2018 with average EC₅₀ values >1 ppm in Denmark. In Sweden, average EC₅₀ values for epoxiconazole reached 1 ppm in 2017. The sensitivity towards prothioconazole remained stable at a high level. Following the decline in sensitivity in vitro, field efficacies of epoxiconazole and prothioconazole decreased from 80 - 90% to 30 - 40% in Denmark and Sweden. Currently, the Danish and Swedish Z. tritici populations are highly adapted to epoxiconazole and prothioconazole. At the same time, a recovery in the sensitivity of tebuconazole and metconazole is observed. Our studies reinforce the view that the principles of anti-resistance management should be applied upon the launch of a new active ingredient to prolong the effective life of both the old and new products.

小麦链霉菌（Zymoseptoria tritici）引起小麦链霉菌斑点病（STB），这是丹麦和瑞典小麦的主要真菌病。疾病控制高度依赖于去甲基化抑制剂（DMI）组中的杀菌剂。自从1970年代引入DMI以来，DMI的使用稳步增长。在过去的十年中，环氧环康唑和原硫代康唑是使用最广泛的活性成分。这项研究的目的是调查Z. tritici对这两种化合物的抗药性。总体而言，从2012年到2019年，共测定了3472株Z. tritici分离株的EC ₅₀值。此外，在田间试验中测试了最常用的DMI化合物的现场性能。EC ₅₀在试验期间，环氧环康唑和原硫代康唑的值增加。在2016年和2018年，环氧环唑出现了显着变化，丹麦的平均EC ₅₀值> 1 ppm。在瑞典，2017年环氧康唑的平均EC ₅₀值达到1 ppm。对原硫代康唑的敏感性保持较高水平。随着体外敏感性的下降，在丹麦和瑞典，环氧环康唑和原硫代康唑的田间药效从80％到90％降低到30％到40％。目前，丹麦和瑞典的Z. tritici人群高度适应环氧环康唑和原硫代康唑。同时，观察到戊唑醇和甲康唑的敏感性有所恢复。我们的研究强化了这样的观点，即在新的活性成分投放市场时应应用抗药性管理原则，以延长新旧产品的有效寿命。