South Africa Wine Research Projects 2026

2. VITICULTURE RESEARCH NEW PROJECT

2.6 GRAPEVINE IMPROVEMENT ESTABLISHMENT OF A WIDE PANEL OF GLRAV-3 VARIANTS FOR EVALUATIONS OF RESISTANCE/DETECTION

PATHSOL GP 26-01 Prof Gerhard Pietersen, Patho Solutions Start date: 2026

AIM AND INDUSTRY RELEVANCE: This project addresses the need for durable resistance to grapevine leafroll-associated virus type 3 (GLRaV-3) by identifying and establishing a representative panel of GLRaV-3 strains present in South Africa. Current resistance screening relies on a limited number of pure virus sources that do not reflect the full local diversity of the virus. By characterising and maintaining pure sources of locally relevant GLRaV-3 variants, the project will support more accurate evaluation of grapevine resistance and improve the reliability of virus detection methods. The project aims to assess the resistance of the GLRaV-3 strain through graft inoculation with five pure sources of GLRaV-3 strains representative of those occurring in South Africa, and to use these to assess the durability of resistance in selected grapevine rootstock clones, such as Ramsey. This will ensure that resistance is effective against a wide range of virus variants before resistant material is released to industry. GLRaV-3 is a significant constraint on grapevine productivity and wine quality. Developing grapevine rootstocks with durable, broad-spectrum resistance will significantly reduce long-term disease risk and management costs for growers. The project will provide the industry with more reliable, disease-resistant planting material and strengthen virus detection, thereby supporting vineyard sustainability and biosecurity.

26

SOUTH AFRICA WINE RESEARCH 2026