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

Shiraz disease.

PHOTO 236. The anatomical composition of a basal shoot section in the context of Shiraz disease in an infected grapevine. Characteristics include the wavy cambium, poorly developed primary phloem and the absence of secondary phloem fibres, as well as a phellogen (cork cambium) (April 2005).

PHOTO 237. Differentiation of abnormally large amounts of phloem tissue at the expense of xylem in peduncles of infected grapevines (March 2005).

154 • A Guide to Grapevine Abnormalities in South Africa