Stress is a state that humans should strive to avoid but when it comes to vines, stress is a very good thing indeed. Very few South African vineyards are stressed because invariably we don’t leave our vines to their own devices. Albertus Louw, Cellar master at Perdeberg Winery, is at pains to stress how important stress is. “Vines, from which the grapes are grown to produce wines, can grow almost anywhere and, if left to their own natural growing patterns, will produce lots of bunches of grapes but of dubious quality.”
While most ‘old world’ vineyards in Europe are farmed dry land, this isn’t the case in South Africa because we have a shortage of water in summer. So, although a good soaking from winter rains is hoped for, the berry size on a bunch of grapes is determined by the lack of water prevalent in summer. This then has a limiting effect on the vine and forces it to switch from growth mode – when it produces more shoots and leaves – to the reproductive mode which is when the concentration of colour and flavour in the berry bursts forth. This is what one wants – small berries – because they allow for a greater ratio of skin to juice. As most of the flavour and colour in red grapes sit in the skin, small berries are jolly good news.
In the case of white grapes, Sauvignon Blanc, Semillon and to a lesser extent Chenin Blanc have big reserves of flavour just under the skin. This means that the suckering of the vines – the removal of young growth – and the shortage of water effectively ‘tricks’ the vine into producing exactly the kind of grapes that will make better wine. The incidence of disease is then minimized by opening up the vine canopy which means less leaves means the vine needs less water and smaller berries usually come in looser bunches that are less prevalent to diseases such as botrytis.
Interestingly, Dr Markus Keller of Washington State University says not all wine grape varieties are alike in their water use. “Some are pessimists, and their stomata close, stopping transpiration, and the water status in the leaf remains -stable. When there’s just a little water stress, the vine thinks ‘Oh heavens, I’m going to run out of water, and the stomata close and growth declines.” Pessimist varieties include Grenache, Tempranillo, and, to some degree, Cabernet Sauvignon. Optimist varieties – i.e. those that believe more water will come like Chardonnary, Riesling, Syrah, Sangiovese and Merlot – keep their stomata open.
A further impact of prevailing dry land conditions on vines is that the vines over many years understand the importance of handling stressful surrounds. They adapt themselves to become the ultimate survivor; they have an ‘adapt or die’ attitude. Just as we humans are toughened up and improved by some harsh life lessons, dry land vines are strong and robust. They have deep and refined root systems that can suck up all the moisture possible and they work efficiently and sparingly with their lifeblood – water. Even the sceptics will admit that the result of dry land farming impacts positively on the quality of the fruit in terms of packing in the flavour. This then translates to the wine, of course, and makes excellent wines.
What better way to toast nature than by enjoying a glass of wine from the Dry Land Collection. This premium wine range from Perdeberg Winery in the Paardeberg is a fine example of how stressed vines yield their very best – here’s how a rough diamond from the earth can be shaped and cut to perfection.