Despite the resistance problems in Monilinia fructicola, demethylation inhibitor fungicides (DMIs) are still effective for the disease management of brown rot in commercial stone fruit orchards in Brazil. This study aims to investigate the sensitivity of M. fructicola isolates and efficiency of DMIs to reduce brown rot. A set of 93 isolates collected from Brazilian commercial orchards were tested for their sensitivities to tebuconazole, propiconazole, prothioconazole, and myclobutanil. The isolates were analyzed separately according to the presence or absence of the G461S mutation in MfCYP51 gene, determined by allele-specific test. The mean EC₅₀ values for G461S mutants and wild-type isolates were respectively 8.443 and 1.13 µg/ml for myclobutanil, 0.236 and 0.026 µg/ml for propiconazole, 0.115 and 0.002 µg/ml for prothioconazole, and 1.482 and 0.096 µg/ml for tebuconazole. The density distribution curves of DMI sensitivity for both genotypes showed that myclobutanil and prothioconazole curves were mostly shifted toward resistance and sensitivity, respectively. Incomplete cross-resistance was detected among propiconazole and tebuconazole in both wild-type (r = 0.45) and G461S (r = 0.38) populations. No cross-sensitivity was observed among wild-type isolates to prothioconazole and the others DMIs tested. Fungicide treatments on detached fruit inoculated with M. fructicola genotypes showed significant DMI efficacy differences when fruit were inoculated with wild-type and G461S isolates. Protective applications with prothioconazole were more effective for control of both G461S and wild-type isolates compared with tebuconazole. Curative applications with tebuconazole were most effective in reducing the incidence and lesion size of G461S isolates. Sporulation occurred only for G461S isolates treated with tebuconazole under curative and preventative treatments. The differences found among the performance of triazoles against M. fructicola isolates will form the basis for recommendations of rational DMI usage to control brown rot in Brazil.

尽管在性问题褐腐病菌，去甲基化抑制剂杀菌剂（DMIS）仍然是有效的褐腐病在巴西商业石果园的疾病管理。这项研究旨在调查M. fructicola分离株的敏感性和DMI减少褐腐的效率。测试了一组从巴西商业果园收集的93株分离物对戊丁康唑，丙环唑，丙硫唑和噻菌灵的敏感性。根据等位基因特异性测试确定MfCYP51基因中是否存在G461S突变，分别对分离株进行分析。平均EC ₅₀Myclobutanil的G461S突变体和野生型分离物的值分别为8.443和1.13 µg / ml，丙环唑为0.236和0.026 µg / ml，丙硫康唑为0.115和0.002 µg / ml，戊唑醇为1.482和0.096 µg / ml。两种基因型的DMI敏感性的密度分布曲线表明，霉菌丁腈和原硫代康唑曲线分别分别向耐药性和敏感性转移。在野生型（r = 0.45）和G461S（r = 0.38）人群中，丙环唑和戊唑醇之间检测不到不完全的交叉抗性。在野生型分离株中对原硫代康唑和其他DMI均未观察到交叉敏感性。毛果分支杆菌接种对离体水果的杀菌剂处理。当用野生型和G461S分离株接种水果时，基因型显示出显着的DMI功效差异。与戊唑醇相比，使用Prothioconazole进行保护性应用对控制G461S和野生型分离株更为有效。戊唑醇的治疗性应用最有效地减少了G461S分离物的发生率和病灶大小。仅在治疗性和预防性处理下，用戊唑醇处理的G461S分离株才发生孢子形成。在三唑类对果蝇分支杆菌的分离性能之间发现的差异，将为建议合理使用DMI来控制巴西褐腐病提供依据。