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Medics cover crop at Boschendal Wine Estate, Franschhoek. (Photo credit: Francois Viljoen).

The South African wine industry is continuously adapting to challenges – from COVID-19 to drought, climate change and shifting consumer trends. This was evident from a series of six regional webinars held by Winetech and Vinpro in May.

Nearly 300 people tuned in for the sessions, which were presented digitally for the first time ever due to COVID-19 restrictions.

Lessons from the drought

Although most vineyards have bounced back from the drought of the previous few years, climate change is still a reality and wine grape producers have learned valuable lessons about optimal water management during the drought.

After the past few dry seasons in the Robertson region, wine grape producers should be mindful of lower reserve levels in the vine. Dr Albert Strever of Stellenbosch University recommended that producers limit over-irrigation and the excessive use of  fertilizer as it can lead to poor shoot ripening and vigorous growth. Strive for balance in leaf management, protect leaf efficacy and prevent too many bud loads.

Drip irrigation systems must be flushed at least once a year to ensure optimal water use. Abie Vorster of Netafim said the first step in any maintenance plan is to do a complete water analysis. Acid is used to remove salt and carbonate deposits in an irrigation system and hydrogen peroxide is used to manage all biological problems.

A long-term water management project was launched in the Olifants River region. Gert Engelbrecht of Vinpro shared the first results and said as more comprehensive results become available, practical demonstrations will be held in commercial vineyards for producers.

A benefit of the drought in the Olifants River region was the fact that the visual and diagnostic incidence of aster yellows disease decreased drastically, which Prof Johan Burger of Stellenbosch University attributed to the absence of alternative host weeds, as well as a decrease in leafhoppers that serve as a vector for the disease.

A study on the effect of climate change confirms that the irrigation and fertilisation of young vines will have to be revised as temperatures and CO2 levels increase. According to research results shared by Dr Hanlé Theron of the Cape University of Technology (CPUT), vines showed good growth as temperature and CO2 levels increased, provided that sufficient water was available.

Soil temperature is a decisive factor when it comes to canopy development, and when it comes to climate change, producers will have to manage this aspect more closely by, among others, sowing cover crops and through tailored irrigation scheduling. According to Prof Alain Deloire of Montpellier SupAgro, there is also a relationship between late pruning and the delayed development of canopies.

Purposeful cover crops

The use of cover crops in the vineyard has now become an indispensable and specialised part of precision wine grape cultivation. “The question is no longer whether or not to plant a cover crop, but rather which one will best suit your goal,” said Hanno van Schalkwyk of Vinpro.

According to Ivan Janse van Rensburg of Barenbrug, a wide range of cover crop species and mixtures are available to achieve specific goals, such as carbon build-up, increasing microbial activity, improving soil aeration, nitrogen binding, weed suppression or the prevention of erosion. The use of a cover crop such as medics on the berm also seems promising in organic cultivation and in cases where wine grape producers want to use less herbicides.

Stoney Steenkamp of Stoney Agricultural Services also suggested that cover crops be planted on the berm under drip irrigation – specifically where intensive irrigation areas experience drought conditions – to ensure good growth. Only 1% of organic matter that is built up due to the cover crops can store between 50 and 75 mm of water and is therefore critical for sustainable farming.

Manage wind and plant spacing

The appearance of wind is one of the most distinctive features of the South African wine industry, and should therefore be a determining factor in vineyard establishment and management. Dr Philip Myburgh of the ARC Infruitec-Nietvoorbij explained that wind causes large-scale evapotranspiration from the soil’s surface, which can be managed by, among others, cover crops, wind breakers, row direction and irrigation scheduling which is continuously reviewed.

Apart from row direction, plant spacing within rows has a significant effect on vine performance, says Dr Kobus Hunter of the ARC Infruitec-Nietvoorbij. An experimental vineyard was established in Robertson showcasing various plant spacing options on high-potential soil. According to Dr Hunter, spacing choices must take a balance between the vine and environmental factors into account.

Eco-friendly practices

Increased demand for biodynamic and organic wines world-wide has led wine grape producers to increasingly adapt their vineyard practices to this movement, including the use of new cover crop species and alternative ways to control weeds, pests and diseases such as trunk diseases.

According to Edo Heyns of AdVini, organic and biodynamic wines provide great market opportunities for those who want to follow this route, and the market is still growing. Although the cultivation of these vineyards presents greater challenges, producers obtain significantly higher price points for organic and biodynamic wines – up to 48% higher in the US compared to conventional wines.

Certain cover crop species can decrease the number of ants in the vineyard, as confirmed by Dr Pia Addison of Stellenbosch University. Research has shown that pathogenic nematodes and fungi hold promise for the control of snout beetles – findings that need to be confirmed under commercial conditions.

Dr Francois Halleen of the ARC-Nietvoorbij explained during a presentation on trunk diseases that dead bearers in Sauvignon Blanc and Cabernet Sauvignon can often be attributed to pathogenic fungi that invade pruning wounds. Pruning wounds can be protected with richoderma, a beneficial fungus.

Wine grape producers from around the world are also looking at greener technologies such as recycling sprays, mechanical weed control devices and partially disease-resistant wine grape varieties. These were some of Conrad Schutte of Vinpro’s technology and research observations during a study tour to Italy in January 2020.

Effect of COVID-19

According to Yvette van der Merwe of the SA Wine Industry Information and Systems (SAWIS), local wine sales were in decline since the end of 2019, in line with international trends. Given an imbalance between supply and demand, partly due to a ban on liquor sales during the COVID-19 restriction, price reductions are expected in the coming year, but are expected to gradually recover in the next two to three years.

In addition to the negative effect on wine sales and prices, the wine tourism sector has also been severely hampered by the COVID-19 restrictions, which contributed to overall cash-flow challenges throughout the wine industry value-chain. Christo Conradie of Vinpro said many wine businesses around the world will not be able to cope. On the plus side, however, there has been an increase in local and international online wine sales and wine industry bodies are constantly working on solutions to mitigate the effect of COVID-19 on businesses and the industry as a whole.

Look out for the next series of Winetech Vinpro Vineyard Webinars to be presented in September this year. Visit www.vinpro.co.za.

MEDIA ENQUIRIES:

Wanda Augustyn
Vinpro Communications Manager
Tel: 021 276 0429
E-mail: wanda@wineland.co.za

 

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