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Vergelegen Wine Estate in Somerset West is making strategic investments in new Cabernet Sauvignon plantings, and experimenting with an alternative trellis system, as part of its ongoing commitment to expressing its unique terroir. This initiative also supports the renowned estate's focus on sustainable viticulture.

Six hectares of new Cabernet Sauvignon vineyards have been planted near the hilltop cellar. The estate is also using the 'stok-by-paaltjie' trellis system, known as ‘staked vines’ or vine by post, with these new plantings, says estate viticulturist Rudolf Kriel.

This is the first time that Vergelegen has implemented 'stok-by-paaltjie'. The estate has traditionally used the vertical shoot position (VSP) trellis system, whereby vine shoots are trained upward in a vertical, narrow curtain, with the fruiting zone below.

With the 'stok-by-paaltjie' method, each vine grows upward along an individual supportive pole. While this approach is more labour-intensive, it optimises land use with a higher density of vines per hectare.

Kriel says his team have planted 6 500 vines/hectare around the cellar using the new trellis system. This compares to 3 330-3 700 vines/hectare elsewhere at Vergelegen.

Wind is also a major consideration, adds Kriel. Under the previous VSP system, five to six vines were planted between poles. Now, individual poles provide greater support for each vine. This is a bonus as, unlike elsewhere on areas of the estate, these hilltop vineyards are not protected by windbreaks of beefwood trees.

Kriel has planted a ground cover crop of clover and medics around the vines. These should provide optimal coverage in two years’ time. The crop will prevent the need for weedicides and manual under-vine maintenance, and produce a “flower garden for bees”, he says.

Oats have been planted in the working zones between vines, to further protect the young vine shoots against wind.

Vergelegen winemaker Luke O’Cuinneagain anticipates that the new trellis system will help the estate enhance fruit purity and structure. "Vines on VSP trellising tend to grow upwards and sprawl at the top. With the ‘stok-by-paaltjie’ system, the leaf canopy should be less vigorous, requiring less mechanical trimming, and encouraging optimal sun exposure," he explains.

Beefwood windbreaks can cause overshading and reduce water availability in their vicinity. "Agricultural land is at a premium," says O’Cuinneagain. "With fewer windbreaks and more 'stok-by-paaltjie' trellising, we can allocate more land to grapevines."

The new trellis system will be implemented elsewhere at Vergelegen, as vineyards require replanting, if the results are positive. "We are always exploring new viticultural techniques," says O’Cuinneagain.

Cabernet Sauvignon is the most prominent grape variety at Vergelegen. It is grown across diverse sites and soil types, mainly Hutton, Clovelly, Pinedene, and Glenrosa.

"Our goal is to achieve a greater expression of our terroir. It’s about respecting the fruit when it comes in, understanding its aromatic expression, and working with the barrels to highlight those characteristics," says O’Cuinneagain.

The Tim Atkin SA Special Report 2024 scored Vergelegen Cabernet Sauvignon Reserve wines (2020-2022) at 93 points. Vergelegen V, the flagship wine mainly comprising Cabernet Sauvignon, scored 93, 94 and 95 points (2019, 2021 and 2022.)

Trellis system research

Research has shown that the choice of trellis can influence grape composition by affecting factors such as light exposure in the bunch zone, air flow through the leaf canopy, and crop load – and, consequently, the primary metabolites (small molecules produced during the metabolism of living organisms) that contribute to the production of secondary compounds in wine.

This is according to research on Chenin Blanc grape quality, working with six trellis types. Tests were conducted by the Department of Viticulture and Oenology at Stellenbosch University, with results published in 2020.

The study showed that “trellising systems can influence amino acids, yeast assimilable nitrogen, phenolic content and aroma compounds, as well as sensory characteristics.”

Find out more about Vergelegen’s wines at https://vergelegen.co.za/wine-range