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

Aster Yellows.

PHOTO 265. In conjunction with hardening and crackling of leaves (Photos 263 & 264) yellowing of leaves in white grape cultivars is common.

PHOTO 266. In red grape cultivars, reddening of leaves is induced by Aster Yellows disease. Note that this phenomenon goes hand-in-hand with a coppery reddening and should therefore not be confused with leafroll.

172 • A Guide to Grapevine Abnormalities in South Africa