This was the crux of the Winetech Vinpro regional information sessions that were attended virtually and physically by around 200 attendees during May.
“These sessions enable producers, viticulturists, winemakers, students, service providers, cellar managers and boards to obtain region-specific information in an easily digestible format, as well as to provide feedback on research needs in their region,” says Conrad Schutte, manager of Vinpro’s consultation service. “The digital platform lends itself to more effective time management and facilitates the distribution of regional information over a wider geographic area.”
Control vineyard growth
After the 2021 harvest season, post-harvest fertilisation is the next important step in the vineyard. Charus du Plessis of Atlantic Fertilizers encourages producers to monitor their vines closely and especially support high-yielding blocks and those that show predominantly poor growth with canopy spray programmes early on in the season.
In the run-up to the next wine grape harvest, it is essential to look at the factors that contribute to optimal ripening. According to Dr Albert Strever of Stellenbosch University, producers should strive for moderate growth, minimal regrowth or no shoot growth until just before veráison. Throughout the season, it is important that leaves and bunches receive optimal sunlight exposure by pruning at the right time, limiting bud loads, suckering well and protecting young leaves by not topping too much or removing branch shoots.
Research by Dr Etienne Terblanche of Vinpro indicates that the ripeness level of Pinotage grapes has a major effect on the fullness and flavour profiles of these wines. Grapes harvested at 23°B lead to a light wine style, 25°B to a medium style and 27°B to a full wine style. In contrast, Pinotage grapes harvested at 29°B lost a lot of weight and led to poor quality wines.
Soil texture influences water strategy
Water management remains one of the most important management aspects in the vineyard, especially within the context of climate change. According to Willem Botha of Netafim, a water management strategy must take into account various aspects, including the soil type, block size and irrigation infrastructure.
First, it is important to determine how water moves in specific soils, which will depend on the soil preparation, type and texture. Many soils will be suitable for either the 2.3- or 4-liter per hour dripper system, but soils with a heavier texture may lead to problems with the infiltration rate. The same applies to coarse sandy soils, where gravitational force can lead to water being irrigated beyond the root zone.
Ward off vineyard diseases
The wine industry has experienced problems with the occurrence of powdery mildew during the past season. According to Pieter le Roux of Villacrop, many vineyards had active powdery mildew on their leaves in the post-harvest period, which can be carried over to the next season, and therefore needs to be treated.
Dirk van Eeden of InteliGro’s advice to wine grape producers is to start spraying for powdery mildew early, use the correct spray intervals and make sure that the dose per hectare is sufficient to ensure good coverage. Also alternate the chemical groups and do not neglect the use of sulphur.
The fight against the leafroll virus continues. Apart from the fact that leafroll-infected vineyards have lower yields, Dr Erna Blancquaert of Stellenbosch University says sensory analyses by winemaker panels indicate that the leafroll virus can have a negative effect on the quality, taste and aroma profiles of wine.
Prof Gerhard Pietersen from Stellenbosch University challenges producers to fight this disease more intensively if they want to get the most out of the long-term investment they have made in their vineyards. According to Pierre-André Rabie of Vinpro, producers who apply complete leafroll control over the long term could achieve a return on investment of up to 17%, compared to producers who do not apply leafroll control and could potentially obtain a negative return on investment.
An integrated approach is required, which includes the removal of leafroll-infected vines, as well as the use of biological and chemical aids. Vaughn Walton of Oregon State University proposed mating disruption of mealybugs (vectors of the leafroll virus) as one biological control strategy, however he suggests that it be used in conjunction with the use of predators and chemical control to combat leafroll.
PathoSolutions has introduced a new app that allows producers to easily mark their virus-infected vines and thereby closely monitor and manage the extent of the virus at vineyard block and even vine level.
The Winetech Vinpro regional information sessions are presented bi-annually in May and September, thanks to the support of the wine industry body for research, technology and innovation Winetech.
“Winetech believes that communicating new knowledge, together with industry partner Vinpro, can stimulate innovative thinking amongst producers,” says Gerard Martin, executive manager of Winetech. “Such thinking can lead to the improvement of processes that can render the producer more profitable and thus more sustainable.”