RT Journal Article SR Electronic T1 Control of Grapevine Leafroll Disease Spread at a Commercial Wine Estate in South Africa: A Case Study JF American Journal of Enology and Viticulture JO Am. J. Enol. Vitic. FD American Society for Enology and Viticulture SP ajev.2013.12089 DO 10.5344/ajev.2013.12089 A1 Gerhard Pietersen A1 Nico Spreeth A1 Tobie Oosthuizen A1 André van Rensburg A1 Maritza van Rensburg A1 Dwayne Lottering A1 Neil Rossouw A1 Don Tooth YR 2013 UL http://www.ajevonline.org/content/early/2013/02/20/ajev.2013.12089.abstract AB Grapevine leafroll disease (LR) is a serious disease of grapevine worldwide, associated with a number of viruses. Grapevine leafroll associated virus 3 (GLRaV-3) is the most important virus associated with this disease in South Africa and in spite of a successful virus-elimination strategy within a certification scheme, spreads rapidly in local commercial vineyards. Since 2002 an integrated control strategy was utilised at a commercial wine estate to control LR and serve as a case study for the local and international wine industries to show that control in a commercial setting is possible. This included planting of certified material tested free of detectable viruses, use of herbicide and subsequent removal of infected vine material, fallow periods during which time volunteer hosts were removed, and the use of systemic and contact insecticides, sanitation and horticultural practices to minimize spread of viruliferous mealybugs. LR was reduced from a 100% infection in 2002 on 41.26 ha (111431 vines) planted mainly from 1989 to 1992, to only 58 LR infected vines detected in 2012 on 77.84 ha (209626 vines), an incidence of 0.027%. This was achieved by replacing the fully infected vineyards and roguing 3105 infected vines within young and replaced new vineyards. The control strategies used were successful in curtailing the spread of leafroll disease and have resulted in the removal of the disease from the majority of individual vineyards. Leafroll currently occurs at sufficiently low levels in the remaining vineyards that local eradication may be possible in these. This is in stark contrast to the general situation in the South African industry where the majority of producers do not apply leafroll control strategies and leafroll spread is rampant.