LELIENFONTEIN DISEASE RESISTANCE EVALUATION STUDY
Our aim: To provide the South African wine industry with disease resistant alternatives of new hybrid species to supplement grape production from existing, conventional clones.
Gieliam Botma, Plant Manager at Bosman Adama Vine Nursery, has also been managing this project. Between 2019 and 2021, 15 new varietals were imported from Germany and Italy for their disease resistant qualities.
The same equation applies as in the previous project:
Disease resistance = less chemical sprays + less tractor diesel + less erosion from tractor tyres + less wear on the tractor
8-12 Vines of each species were planted out in a trial block.
These vines were managed conventionally, except they were only sprayed once a year for downy and powdery mildew, rather than the usual 6-8 sprays per year.
They were assessed on the following: colour, visual diseases, compactness of bunch, yield, growth potential, vigour and ripening period. While the focus was on disease resistance, earlier ripening varietals require significantly less water therefore making them even more environmentally friendly.
After 4 years, the grapes were harvested and vinified separately at the University of Stellenbosch. Between 10 and 30 bottles of each grape cultivar were made. A group of around 45 independent winemakers and viticulturists were invited to a technical tasting of all of these wines and they were asked to taste and evaluate them.
The tasting data was collated along with the data that Gieliam had already collected in terms of performance and the 15 cultivars were whittled down to the 5 best:
- Helios
- Monarch
- Muscaris
- Solaris
- Souvignier Gris
A few vines of the first 4 cultivars were sold to a small group of interested wine growers, who have each planted a test block.
Bosman Adama has planted out 1 500 vines of Souvignier Gris. These vines were planted closer together than conventional varietals because their disease resistance means they are less susceptible to downy and powdery. So therefore, the yield will be higher than a conventional vineyard and/or by cultivating a smaller piece of land, the carbon footprint is smaller.
As these cultivars are unknown to the market, initially we do not expect them to be vinified and bottled on their own as they are unknown to wine consumers. However, these wine grapes can be blended with other better-known cultivars. These disease resistant cultivars can be added in to increase production volume and potentially improve the wine without changing the label on the bottle. For example, Souvignier Gris is very similar to Pinot Gris which is currently a very popular wine.
This is the only such project taking place in South Africa.
What does this mean for Bosman Family Vineyards wines?
Having generated the research, we can propagate and plant these vines and produce wine, providing assurance to our consumers of the quality and sustainability of our wines as well as their provenance.
What does this mean for the wider supply chain?
Wine farmers will now be able to reduce their own carbon footprint by planting these more resilient grape cultivars, reducing their carbon footprint and ultimately, that of the Cape wine industry as a whole.
