The cold, wet winter that most wine grape growing regions have experienced so far is good news for producers, who are already preparing vineyards for the 2021 wine grape harvest.
“The frequent cold fronts that have occurred in the Western Cape, characterised by low temperatures, rain and snow, are very positive in terms of wine grape cultivation,” says Vinpro viticulturist Etienne Terblanche. Along the Orange River, below-average minimum temperatures were also recorded, which bodes well for the producers in the area.
According to Etienne, low temperatures are also optimal in terms of vine physiology. “Vineyards need a good build-up of cold units during winter to ensure even budding later in the season. The cold weather is beneficial as it allows the plant to remain dormant during winter. At consistent low temperatures the vines are able to go into an optimal state of rest, avoiding the use of important reserves they will need for new growth when the weather warms up during spring.”
Apart from good penetrating rainfall that fills soil profiles and increases to run-off to dams, snow makes a big contribution to soil water levels. “The fact that it melts slowly ensures deep and proper soil penetration. As it melts, the snow on the mountains also move in between crags and boulders to replenish some of the underground water reserves which were extracted through boreholes during the previous drought period,” says Etienne.
Due to the hot and dry seasons the industry experienced in recent years, soils in warmer and drier regions became increasingly brackish. The frequent rain – especially in the form of proper downpours – flushed these salts from the root zone, which is very beneficial to soil and vine health.
Wine grape producers are also now hard at work pruning, in preparation for the 2021 wine grape harvest. According to Conrad Schutte, manager of Vinpro’s viticultural consultation service, the pruning period usually extends from mid-June for earlier cultivars to mid-September for late cultivars such as Cabernet Sauvignon, depending on the amount of hectares that a producer has to prune.
“The rule of thumb is ‘prune early, prune wood; prune late, prune fruit’. If you prune early, you stimulate vegetative growth, and if you prune late, you greatly stimulate the crop load. This helps us to determine the most effective time to prune,” Conrad says.
As part of a regular Wingerddinge column in WineLand magazine, Vinpro shares the following tips:
- The ideal time to prune is three to four weeks before the date on which vines are expected to start budding, and pruning should be clean and blunt in one action. In frost-sensitive areas, this can be done during bud swelling.
- Where budding stimulants are applied three to five weeks before budding, a good synergistic effect is obtained if the pruning (in one action) and application of budding stimulants are timed together as closely as possible.
- Use wound sealants such as Trichoderma in high rainfall areas, as well as on cultivars such as Sauvignon Blanc, which are more sensitive to Eutypa-dieback.
- Manage weeds on the berm with a product depending on the type and status of the weeds.
- Under dry winter conditions and in dryland vineyards, cover crops should preferably be sprayed before budding and flattened to ensure the best preservation of dry material.
- Apply the correct planting techniques, especially when making planting holes. This will ensure successful establishment, as well as the lifespan of a vineyard.
- Apply irrigation system maintenance.
- Plan the spring herbicide programmes, as well as fertiliser and spraying programmes, in collaboration with chemical representatives and order the necessary products.
- Always keep the IPW guidelines in mind.
- Calibrate spraying pumps and fertiliser spreaders.