The occurrence of bakanae disease of rice caused by the fungus Fusarium fujikuroi in Zhejiang Province has become increasingly aggravated in recent years, concomitant with the development of resistance to the widely applied fungicides, prochloraz and phenamacril. In this study, the activity of a novel succinate dehydrogenase inhibitor (SDHI) fungicide, penflufen, against different fungi was evaluated in addition to the potential of penflufen in controlling F. fujikuroi infections. Penflufen exhibited good bioactivity against F. fujikuroi, but weak activity against Fusarium spp. and other investigated plant-pathogenic fungi including Colletotrichum spp. In addition to inhibiting mycelial growth, penflufen effectively inhibited F. fujikuroi conidium production. For germination, penflufen could effectively inhibit that of small conidia, but only delay the germination of large conidia. In addition, the sensitivity to penflufen among 100 F. fujikuroi isolates that were collected in areas that were never exposed to SDHIs was determined based on mycelium growth. Sensitivities surprisingly exhibited bimodal distributions, indicating the presence of natural resistance. Cross-resistance was not observed between penflufen in F. fujikuroi and two fungicides that have been extensively applied in field including prochloraz (a DMI) and phenamacril (a 2-cyanoacrylate fungicide), nor with the three SDHIs, fluopyram, benzovindiflupyr, and pydiflumetofen. Additional analysis identified five different point mutations in SDH-A (i.e., at residues 46, 225, 283, 430, and 586) of naturally resistant isolates. These results inform the potential application of the new SDHI fungicide penflufen for managing crop diseases and understanding possible resistance mechanisms among pathogens.

近年来，随着对广泛应用的杀菌剂丙氯胺和苯那克林产生抗药性，浙江省由藤黑镰刀菌引起的水稻稻瘟病的发生日趋严重。在这项研究中，除了苯氟丙胺控制F. fujikuroi感染的潜力外，还评估了新型琥珀酸脱氢酶抑制剂 (SDHI) 杀真菌剂苯氟丙胺对不同真菌的活性。Penflufen对F. fujikuroi表现出良好的生物活性，但对Fusarium spp的活性较弱。和其他研究的植物病原真菌，包括炭疽菌属 除了抑制菌丝体生长外，penflufen 还有效地抑制了F. fujikuroi分生孢子的产生。在萌发方面，戊氟芬能有效抑制小分生孢子的萌发，但只能延缓大分生孢子的萌发。此外，在从未接触过SDHI 的区域收集的100 株F. fujikuroi分离株对 Penflufen 的敏感性是根据菌丝体生长确定的。敏感性出人意料地表现出双峰分布，表明存在自然电阻。在藤黑梭菌中未观察到戊氟芬之间的交叉耐药性以及已广泛应用于田间的两种杀菌剂包括丙氯灵（一种DMI）和苯那克林（一种2-氰基丙烯酸酯杀菌剂），也没有与三种SDHI，即氟吡菌酰胺、苯并氟啶虫脒和吡氟甲醚一起使用。额外的分析鉴定了天然抗性分离株的 SDH-A 中的五个不同点突变（即，在第 46、225、283、430 和 586 位残基处）。这些结果为新型 SDHI 杀菌剂 Penflufen 的潜在应用提供了信息，可用于管理作物病害和了解病原体之间可能的抗性机制。