WINETECH Technical Yearbook 2019

A potential threat to vineyards and an unexplored, fascinating subject for scientific study. Grapevine species Vitis vinifera is planted on about 7.4 million hectares, being one of the most economically important crops worldwide (Anonym, 2018A). At the end of the nineteenth century, vineyards in Europe and South Africa were devastated by a tiny sap-sucking insect known as phylloxera ( Dactulosphaira vitifoliae ), which feeds on leaves and roots of grapevines. The insect was introduced to Europe from North America and was spreading fast in vineyards as it could not be controlled with chemicals. The grapevine industry was rescued with the introduction of grafting Vitis vinifera onto native American Vitis species, usually hybrids created from V. berlanderi , V. riparia and V. rupestris , which are naturally resistant to phylloxera (Anonym, 2019). Since then grafting has become a common practice in viticulture. DARIUSZ GOSZCZYNSKI: Plant Health and Protection, Agricultural Research Council, Pretoria KEYWORDS: Rugose wood diseases, associated viruses, corky bark disease on LN33 indicator. NOVEMBER 2019 RUGOSE WOOD DISEASES AND ASSOCIATED VIRUSES

A B PHOTO 1. Canes of LN33, which are (A) disease-free and (B) exhibit severe symptoms of CBD.