South African Wine - Viticulture

Viticulture

Historically vineyards in South Africa were planted with untrellised bush vines planted 1.2 metres (3 ft 11 in) apart at a density of 7,000 vines per hectare (2,800 vines per acre). Following the phylloxera devastation, the focus of viticulture in South Africa was more on quantity rather than quality. Vineyards were planted with high yield varieties, widely spaced to facilitate the use of mechanical harvesting. In the late 20th century more producers began to focus on quality wine production and adopted modern viticultural practices. Vines were planted to an average density of 3,300 per hectare (1,300 per acre) and pruned to keep yields down to 49–56 hl/ha (2.8–3.2 tons/acre). The most common form of trellising found in South Africa is the vertical hedge row system that uses a split cordon supported on a wire kept around 750 millimetres (2.46 ft) off the ground. The grapevine leaves are trained upright on separate wires that allow plenty of sunshine to reach the grapes but provide enough coverage to keep them from being sunburned. The vines are usually pruned to allow four to five spurs each with two to three buds (potential grape clusters) per cordon. Heat is also a concern come harvest time with some wineries harvesting only at night in the cooler temperatures under floodlights.

The lack of precipitation in many wine regions makes irrigation a necessity. Sprinkler and drip irrigation systems are used to provide anywhere from 200–700 millimetres (7.9–28 in) of extra water a year. Modern winemakers are developing new techniques and an understanding of the role that water stress plays in the development of quality wine grape production. Producers who do not irrigate will sometimes use the phrase "dryland" or "dry farmed" on their wine labels as marketing angle. Besides irrigation, an important concern for vineyard owners is the threat of vineyard pests such as mealy bugs and baboons. To combat these hazards, some vineyard owners will utilise Integrated Pest Management (IPM) programs such as the importation of ladybugs, a natural predator of mealy bugs.

While ocean winds keep some fungus and mildew threats at bay, downy mildew and powdery mildew (known regionally as "white rust") can pose an occasional threat during the wet winter season. Near harvest time botrytis can also appear, being a hazard or a welcome visitor depending on whether or not botrytised wine production is the goal. Another threat is diseased and virus-infected rootstock. After the phylloxera devastation, vineyards in South Africa were replanted with American rootstock (nowadays most commonly Richter 99 and Richters 101-14). Some of these rootstocks that were imported were infected with various virus such as corky bark, fanleaf and leafroll, which soon spread to other vineyards. These virus-infected vines have a shortened life span and difficulties with photosynthesis, which can lead to poor ripening of phenolic compounds in the grape and low quality wine. Since the 1980s, efforts have been undertaken by the South Africa wine industry to quarantine and promote healthy virus-free vineyards. Additionally, work has been undertaken in clonal research to identify which grape varieties grow best in which climate and wine region.