No abstract

Athelia rolfsii is a devastating soil-borne pathogen that causes stem rot of peanut and severely constrains the peanut production. The new generation of succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr has been registered in United States and Brazil for managing multiple plant diseases. However, it is not registered in China to control peanut stem rot. In this study, 246 isolates obtained from major peanut production areas in Shandong, Henan and Hebei Province of China were used to determine the baseline sensitivity of A. rolfsii to benzovindiflupyr. The frequency of EC50 values of benzovindiflupyr was unimodally distributed with an average EC50 of 0.12 mg/L and a range of 0.01-0.57 mg/L. Benzovindiflupyr can also strongly inhibit the germination of sclerotia, with an average EC50 of 2.38 mg/L (N= 23). In addition, benzovindiflupyr exhibited great in vivo efficacy against A. rolfsii, that the protective or curative efficacy (89.87%, 20.39%) of benzovindiflupyr at a concentration of 50 mg/L was equivalent to that of the control fungicide thifluzamide at 100 mg/L (86.39%, 16.21%). At the same concentration (e.g., 100 mg/L), the protective efficacy (93.99%) of benzovindiflupyr was more than twice as high as the curative efficacy (45.07%). A positive correlation was existed between benzovindiflupyr and isopyrazam or mefentrifluconazole, which was possibly resulted from similar chemical structures or the damage of cell membrane. Our findings provided valuable information for the application of benzovindiflupyr, and the established baseline sensitivity could facilitate the monitoring and assessment of benzovindiflupyr resistance risk.