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

PLANT MATERIAL PROBLEMS 1 I n South Africa a very high premium is placed on plant improvement – which entails that all the material, whether from imported or locally developed clones and cultivars, are subject to extremely strictly controlled improvement processes before they are made available to the industry. Currently the SA wine industry has mainly two plant improvement institutions, namely: (i) Vititec and (ii) Ernita Nur- sery (Distell), which continuously strive for a communal goal – based on the issuing of exclusively the best available viticulturally and oenologically selected clone material, which tests free of known harmful viruses and virus-like entities. Based on the fact that tissue culture techniques ( in vitro cultures) represent an essential link with plant material improvement, intensive and comprehensive research on this subject was launched (since 1977) by the Department of Viticulture and Oenology, Stellenbosch University – with specific objectives to develop such techniques for local conditions, to provide for among others the successful elimination of harmful viruses and related entities (Goussard, 1981, 1982, 1984, 1985, 1987). Arising from this pioneering work and later co-operation with abovementioned entities, technology as related to these techniques (Goussard & Wiid, 1989; Goussard et al., 1991; Goussard & Wiid, 1992, 1995) were developed and refined to world standards – and are currently still applied very successfully in plant material improvement processes. In terms of the Plant Improvement Act, the Vine Improvement Association (VIA) is the delegated authority which co-oridinates plant improvement in wine grapes in South Africa and administers the SA Certification Scheme for Wine Grapes. Clones which are developed and of which material has completed the total cycle of plant improvement (clone selection, virus detection and elimination, as well as local evalution in the field of viticulture as well as oenology), are registered with the VIA, after which grafting material is issued from approved sources as ‘SA Certified’.

8 • A Guide to Grapevine Abnormalities in South Africa