It is said that 'quality wine is created in the vineyard'. Except for the usual concept of 'terroir', very little is written about the role that viticulture plays in wine quality. It's a huge topic, but what better place to start, than with the vine itself.
It is a little known fact that the majority of vines planted world-wide use the roots of another vine to extract the water and nutrients they need. When you visit a vineyard; the vines you see above ground, whether they be; Sauvignon, Chardonnay or Syrah, actually belong to the European vine species, 'Vitis vinifera'. However below ground, the roots of these vines belong to another species altogether.
The roots of 'Vitis vinifera' are acutely prone to two devastating soil borne pests; the dreaded louse, 'Phylloxera' and the lesser-known but far more widespread microscopic worm 'Nematodes'. European winemakers found this out with devastating effect in the 1860's when Phylloxera, native of the United States, was unintentionally introduced. It resulted in the death of millions of vines across Europe.
A solution was found, as many of the wild vine species native to the US had built up a natural resistance to Phylloxera. These obscure relations to the European grapevine are in fact scrawny, sprawling vines. However, by grafting the wine grape Vitis vinifera onto the roots of these species (or their crosses), it was found that the resulting vine could withstand the damage of phylloxera.
Later it was found that vines grafted onto various rootstocks grew better in saline, acidic, clay, limestone or drought prone soils, and most produced much higher grape yields compared with vines grown on their own roots. Some people claim that they can taste the difference between ungrafted grapes and grafted grapes.
So next time you visit a winery, as well as asking what oak they use, also ask if their vines are on rootstock and if so, which? It's a good question as the rootstock on which the grapes grow, have at least as much impact on the wine you are drinking.