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

Manganese deficiency (478); boron toxicity (479).

PHOTO 478. An increase in intensity of interveinal chlorosis in leaves (compare Photo 477) that may be ascribed to manganese deficiencies.

PHOTO 479. Boron toxicities are associated with, inter alia, shattering of berries; onset of necrotic blemishes in older leaves; shortened internodia with a ‘zig-zag’ appearance and growth arrest in apical leaf edges – thereby contributing to smooth edges and knobbly surfaces on leaves.

306 • A Guide to Grapevine Abnormalities in South Africa