The Intergovernmental Panel on Climate Change has predicted that climate change could wipe out more than half of the world’s vineyards by 2050.
At an Old Vine Project (OVP) workshop held recently near Stellenbosch, OVP co-founder Rosa Kruger said wine farmers had to be far more strategic and take many more variables into account when planting new vineyards. This was all the more pertinent if they wanted their vineyards to last longer than 35 years in order to be classified as heritage vines.
According to Kruger, the selection of rootstocks and varieties should be based on their ability to withstand climatic shocks, such as floods and droughts, as well as their resilience to disease. One of her suggestions was to choose varieties that ripened earlier in the season, before heatwaves could affect the acidity in the wines.
Vineyard design
In addition, far more attention needed to be paid to the design of vineyards to improve their water-use efficiency and drainage.
For example, planting vineyard rows in a north-west/south-east orientation could prevent sunburn caused by direct sunlight. If the slope dictated a north-south row orientation, a sprawl system would allow for dappled rather than direct sunlight.
Kruger explained that if grapes were exposed to direct sunlight, the temperature in the berries would escalate during a heatwave and have an adverse effect on the juice.
“With temperatures getting higher, we need to ensure that grapes ripen naturally and aren’t ‘cooked’ ripe, as this will have a negative impact on wine quality. Wine grapes need dappled, not direct, sunlight,” she said.
To ensure good drainage and prevent erosion and landslides, farmers either needed to invest in expensive, expertly built drains, or plant along the natural contours of the land.
“The use of contours is actually an old concept; Prof WJ Talbot published a book about it, titled Swartland and Sandveld, in the late 1940s. He listed water conservation, reduced erosion, and the slower movement of water through the soil as only a few of the benefits of [contour farming],” said Kruger.
She opposed the use of terraces, however, as these left vineyards doubly exposed to sunlight, heat and drought, and disturbed the natural layers of the soil.
Vines should be leaner and less vigorous, as vineyards with large leaves, long shoots and bigger berries needed more water and were more sensitive to heatwaves.
Vineyards could be planted at higher altitude, as temperatures could be up to 1°C cooler for every 100m gain in elevation.
Click HERE to read the full article.