Chilean Wine - Viticulture

Viticulture

Chile's natural boundaries (Pacific Ocean, Andes Mountain, Atacama Desert to the north and Antarctica to the south) has left it relatively isolated from other parts of the world and has served to be beneficial in keeping the phylloxera louse at bay. Because of this many Chilean vineyards do not have to graft their rootstock and incur that added cost of planting. Chilean wineries have stated that this "purity" of their vines is a positive element that can be tasted in the wine but most wine experts agree that the most apparent benefit is the financial aspect. The one wine region that is the exception to this freedom from grafting is Casablanca Valley whose vines are susceptible to attack by nematodes. While phylloxera is not a problem, winemakers do have to worry about other grape diseases and hazards such as downy mildew, which was spread easily by El Niño influences and severely affected the 1997-1998 vintages. Powdery mildew and verticillium wilt can also cause trouble.

There is not much vintage variation due to the reliability of favorable weather with little risk of summer time frost or harvest time rains. The main exception, again, is Casablanca due in part to its closer proximately to the Pacific. For the Chilean wine regions in the Valle Central, the Andes and Coastal Ranges create a rain shadow effect which traps the warm arid air in the region. At night, cool air comes into the area from the Andes which dramatically drops the temperature. This help maintain high levels of acidity to go with the ripe fruit that grapes develop with the long hours of uninterrupted sunshine that they get during the day. The result is a unique profile of flavonoids in the wine which some Chilean wineries claim make Chilean wines higher in resveratrol and antioxidants. Harvest typically begins at the end of February for varieties like Chardonnay with some red wine varieties like Cabernet Sauvignon being picked in April and Carmenère sometimes staying on the vine into May.

The Andes also provide a ready source of irrigation which was historically done in flood plain style. Chilean vineyard owners would dig canals throughout their vineyards and then flood the entire surface area with water allowing some to seep into the ground and the run off to be funnel away through the canals. This encouraged excessive irrigation and high yields which had a negative effect on quality. During the wine renaissance of the 1980s & 1990s more vineyards converted to drip irrigation system which allowed greater control and helped reduce yields. The soil composition of Chile's vineyards varies from the clay dominated landscapes of Colchagua, which is thus heavily planted with the clay-loving Merlot, to the mixture of loam, limestone and sand found in other regions. In the southern Rapel and parts of Maule, tuffeau soil is present with volcanic soil being found in parts of Curico and Bio-Bio.