Sensitivity of Pseudoperonospora cubensis to dimethomorph, metalaxyl and fosetyl-aluminium in Shanxi of China

► This study introduced the concept of fungicide resistance index to describe fungicide resistance levels. ► Our study reports high resistance of Pseudoperonospora cubensis to metalaxyl in Shanxi Province. ► We show that low resistant of P. cubensis to dimethomorph occurred in Shanxi Province. ► No cross-resistance was found among Metalaxyl, Dimethomorph and Fosetyl-aluminium.