Which common grape varieties are particularly prone to powdery mildew?

• A. Pinot, Riesling
• B. Chardonnay, Riesling
• C. Chardonnay, Cabernet
• D. Cabernet, Pinot

Answer: (C)

Powdery mildew susceptibility varies by grape variety because growth habits and fruit characteristics create different microclimates and nutrient conditions for the fungus. Chardonnay and Cabernet Sauvignon are two varieties that are commonly cited as particularly prone to powdery mildew. Their vigorous canopies and typical fruiting patterns can create favorable conditions for the fungus to establish on leaves and berries, especially in climates with warm days and humid nights. Because these varieties are widely grown and frequently encountered in vineyards, they often show higher disease pressure, making them classic examples of prone cultivars. While other varieties can be affected as well, Chardonnay and Cabernet Sauvignon are the ones most often highlighted for their susceptibility in practical viticulture.