The resistance of cucumber to downy mildew varies from place to place. It is suggested that one or two of dimethomorph, pyrimethanil, propamocarb hydrochloride, metalaxyl, pyrimethanil, flumorph, oxadiazon, flufenoxamide and oxadiazon be used alternately (in severe cases).

(If it is a protective greenhouse, pay attention to humidity control. It is recommended to use chlorothalonil aerosol to control the disease in rainy days. )

Prevention first, comprehensive prevention (disease prevention, dose reduction by one). Use pesticide ingredients alternately, and don't use the same pesticide ingredients continuously. This is the principle of plant protection.