Demethylation inhibitor (DMI) fungicides are used to control brown rot in stone fruit worldwide. However, their specific mode of action can select resistant isolates of Monilinia fructicola. Monilinia fructicola resistant to DMI fungicides are associated with a fitness cost in the absence of selective pressure, indicating that the sensitive population can be re‐established when discontinuing the fungicide in the field. This work aimed to build up the sensitive population of M. fructicola after discontinuing the use of tebuconazole for successive crop seasons. The sensitivity of M. fructicola to tebuconazole was assessed in four commercial peach orchards in Paraná and São Paulo States from 2012/13 to 2015/16. Different fungicide programmes were used and DMI fungicides were discontinued from 2013/14. The sensitivity of M. fructicola to tebuconazole was assessed by a mycelial growth assay in vitro and by determining the frequency of the G461S mutation in the MfCYP51 gene. The isolates from Paraná had high sensitivity to the fungicide across all seasons and the frequency of the G461S mutation remained below 5%. The isolates from São Paulo were highly resistant in the 2012/13 season; however, there was a gradual decline until 2015/16. In addition, the G461S mutation frequency in Sao Paulo State was about 80% in the 2012/13 season, but reduced until it was completely undetectable in 2015/16. These results provide evidence that resistance can be managed in orchards with high selective pressure to tebuconazole after discontinuing the use of the fungicide for at least 3 years.

中文翻译：

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在田间停药对戊唑醇可恢复果核果园中念珠菌的敏感性

去甲基化抑制剂（DMI）杀菌剂用于控制全世界核果中的褐腐病。但是，它们的特定作用方式可以选择抗褐腐莫妮菌的菌株。在没有选择压力的情况下，对DMI杀真菌剂有抗药性的念珠菌会增加健身成本，这表明在田间停用杀菌剂时可以重新建立敏感种群。这项工作旨在在连续的作物季节中停止使用戊唑醇后，增加果蝇的敏感种群。毛果分支杆菌的敏感性在2012/13年至2015/16年间，在巴拉那州和圣保罗州的四个商业桃园中对戊唑醇的残留量进行了评估。从2013/14年开始，使用了不同的杀菌剂程序，并且不再使用DMI杀菌剂。的灵敏度M.腐病菌戊唑醇用菌丝体生长测定法评估在体外并且通过确定在所述G461S突变的频率MfCYP51基因。在所有季节中，巴拉那州的分离株对杀菌剂均具有较高的敏感性，G461S突变的频率仍低于5％。来自圣保罗的分离株在2012/13赛季具有很高的抗性。但是，直到2015/16年度才逐渐下降。此外，圣保罗州的G461S突变频率在2012/13年度约为80％，但一直降低到2015/16年度完全检测不到。这些结果提供了证据，表明在停止使用杀真菌剂至少3年后，在具有高选择性压力的果园中对戊唑醇的抗性可以得到控制。