Bioactivity and Resistance Risk of Fluxapyroxad, a Novel SDHI Fungicide, in Didymella bryoniae

作者：Xuewei Mao, Zhiwen Wu, Feifei Zhao, Xin Yang, Mingguo Zhou, Yiping Hou · 发表于：Plant Disease · 年份：2023 · DOI：10.1094/pdis-07-23-1374-re · 被引用次数：6 · 研究领域：Fungal Plant Pathogen Control、Plant Pathogens and Fungal Diseases、Entomopathogenic Microorganisms in Pest Control

Gummy stem blight, caused by Didymella bryoniae, is an important disease in watermelon in China. Fluxapyroxad, a new succinate dehydrogenase inhibitor fungicide, shows strong inhibition of the mycelia growth of D. bryoniae. However, its resistance risk in D. bryoniae is unclear. In this research, the sensitivities of 60 D. bryoniae strains to fluxapyroxad were investigated. The average EC 50 value and MIC values of 60 D. bryoniae strains against fluxapyroxad were 0.022 ± 0.003 μg/ml and ≤0.1 μg/ml for mycelial growth, respectively. Eight fluxapyroxad-resistant mutants with medium resistance levels were acquired from three wild-type parental strains. The mycelial growth and dry weight of mycelia of most mutants were significantly lower than those of their parental strains. However, four resistant mutants showed a similar phenotype in pathogenicity compared with their parental strains. The above results demonstrated that there was a medium resistance risk for fluxapyroxad in D. bryoniae. The cross-resistance assay showed that there was positive cross-resistance between fluxapyroxad and pydiflumetofen, thifluzamide, and boscalid, but there was no cross-resistance between fluxapyroxad and tebuconazole and mepronil. These results will contribute to evaluating the resistance risk of fluxapyroxad for managing diseases caused by D. bryoniae and further increase our understanding about the mode of action of fluxapyroxad.