The potential of cultivar mixtures to reduce disease severity and increase yields in cereals across the globe is well established. The effect of cultivar mixtures on the selection for pathogen strains resistant to specific fungicides has, however, not previously been investigated. In this study, the case of the pathogen Zymoseptoria tritici causing Septoria tritici blotch in wheat (Triticum aestivum) and resistance development to azole fungicides by single mutations in CYP51 was explored. Cultivar mixtures composed of a range of resistant and susceptible winter wheat cultivars were grown across a total of seven field trial sites and three growing seasons. The treatments consisted of untreated plots and plots with one, two, or three fungicide applications. From the trials, the economically optimal fungicide input was calculated and the level of fungicide resistance was measured as the frequency of key CYP51 mutations. The study demonstrates for the first time how cultivar mixtures can reduce the selection for fungicide resistance and can reduce the need for fungicide input. Based on four trial sites in two growing seasons, the majority of cultivar mixtures reduced the frequency of a CYP51 mutation compared with the component cultivars in pure stand. The highest significant reduction in mutation frequency by a cultivar mixture was 73%. Conditions with high fungicide input and low disease severity resulted in the most pronounced reductions in mutation frequency by cultivar mixtures. The economical need for using fungicides was also impacted by cultivar mixtures when compared with pure stand. Based on six trial sites across two growing seasons, the majority (67%) of cultivar mixtures had the potential to reduce the number of fungicide applications compared with their pure stand counterparts. These findings could have notable implications for intensive crop production. Within-field diversity can reduce the threat from diseases that have become resistant to fungicides and contribute to creating a more sustainable production where lower chemical inputs can sustain high yields.

中文翻译：

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栽培品种混合物减少杀真菌剂输入并减轻杀真菌剂抗性发展的潜力

品种混合物在全球范围内降低疾病严重程度和增加谷物产量的潜力已得到广泛认可。品种混合物对选择对特定杀真菌剂具有抗性的病原体菌株的影响尚未得到研究。在这项研究中，病原体小麦枯萎病菌引起小麦小麦枯萎病的病例（小麦）），并探索了通过CYP51的单突变对吡咯类杀菌剂的抗性发展。在七个七个田间试验场和三个生长季节中，分别种植了由一系列抗性和易感冬小麦品种组成的品种混合物。处理包括未经处理的地块和施用一种，两种或三种杀菌剂的地块。从试验中，计算出经济上最佳的杀菌剂输入量，并以关键的CYP51突变的频率测量杀菌剂的抗性水平。该研究首次证明了栽培品种混合物如何减少抗真菌剂的选择并减少对杀真菌剂的需求。根据两个生长季节中的四个试验地点，与纯种中的组成品种相比，大多数品种混合物降低了CYP51突变的频率。品种混合物对突变频率的最高显着降低是73％。高杀真菌剂输入和低疾病严重度的条件导致品种混合物的突变频率降低最明显。与纯林相比，使用杀菌剂的经济需求也受到品种混合物的影响。根据两个生长季节的六个试验点，与纯林分品种相比，大多数品种混合物（67％）具有减少杀真菌剂施用数量的潜力。这些发现可能对集约化作物生产产生显着影响。