A Guide to Grapevine Abnormalities in South Africa - P.G. GOUSSARD

Downy mildew.

PHOTO 36. A typical example where white fungal growth occurs on the undersides of leaves without the characteristic yellow oil spots on top. This phenomenon generally occurs late in the season – usually after the harvest.

PHOTO 37. Downy mildew on leaves late in the season. Note the absence of yellow oil spots.

32 • A Guide to Grapevine Abnormalities in South Africa