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

Virus associated phenomenon (1); thickened graft union (2).

PHOTO 1. The visual appearance of this young Pinotage grapevine reveals a typical closterovirus associated phenomenon. Similar situations emphasise the necessity to consistently use certified material for new plantings.

PHOTO 2. A typical thickened graft union (not to be confused with Shiraz decline or crown gall) associated with ineffective graft union healing. As a result of superfluous callus formation from the scion, with little or none of it from the rootstock component, the latter appears to be strangled. In such instances it is most likely that no cambial bridging takes place with a concomitant lack of vascular tissue differentiation and connection, thus causing the grafted combination to die back.

10 • A Guide to Grapevine Abnormalities in South Africa