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

Downy mildew.

PHOTO 32. The irregularity in extent and size of the spots (Photo 31) on individual leaves is demonstrated here. This is not to be confused with oidium or herbicide damage.

PHOTO 33. In red juice cultivars such as Alicante Bouschet downy mildew spots turn red rapidly.

30 • A Guide to Grapevine Abnormalities in South Africa