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

Nitrogen toxicity (466); potassium deficiency (467).

PHOTO 466. A characteristic example of nitrogen toxicity in this Shiraz grapevine, with shiny, dark green leaves, and browned edges that tend to curl upwards.

PHOTO 467. Normally potassium deficiencies are manifested as curled leaves during the early part of the growing season – as illustrated by this Sultanina grapevine, where the curling action occurs upwards.

300 • A Guide to Grapevine Abnormalities in South Africa