First Paragraph: Powdery mildew is one of the most important and widely distributed diseases of grapevines in California vineyards. This fungus disease occurs in all of the grape-growing regions of the state, develops and spreads very rapidly under favorable weather conditions, and can destroy entire crops in any season. However, sulfur treatments can prevent powdery mildew, and drenching the diseased vine with water and wetting agent can eradicate it.
