South Africa Wine Technical Yearbook 2025

Long-term sustainability – a call to action Looking ahead, Gladstones (2011) calls for the wine industry to embrace long-term planning and sustainability. He advocates for adopting organic, biodynamic and regenerative agriculture practices, which could mitigate environmental impact and enhance economic stability in the face of a changing climate. Collaboration and information sharing within the industry are also vital in ensuring winemakers stay ahead of climate risks. By working together, the industry can develop innovative solutions and policies to protect the vineyards and the winemaking legacy (Gladstones, 2011). Cultivar and nutrient dynamics in a changing climate Beyond climate, the soil – rich in nutrients and microorganisms – plays an equally vital role in shaping wine quality. Healthy soils provide essential macronutrients like nitrogen, phosphorus and potassium, which are crucial for vine growth. A study by Maathuis (2009) highlights the importance of these nutrients in supporting photosynthesis and fruit development. However, micronutrients like zinc, copper and iron are equally essential, although required in smaller amounts. Sharma et al . (2024) and other authors say these micronutrients boost plant productivity and resilience. Research by Gobbi et al . (2023) and other authors further emphasises the importance of microbial communities in soil, showing how microorganisms like Rhizobia and Bacillus contribute to nutrient cycling, influencing grapevine health and wine quality. These microbes help fix atmospheric nitrogen and make phosphorus more accessible to the vines, highlighting the intricate connection between soil biology and terroir (Gobbi et al ., 2023). Understanding the impact of terroir on wine quality – a look at soil, climate and microbial influence The concept of “terroir” in winemaking goes beyond just geography. Terroir encompasses a range of environmental factors – including climate, soil, topography and even microbial life – that influence the growth of grapevines and ultimately determine the quality of the wine produced. According to Seguin (1986, 1988), these elements combine to form a unique ecosystem that shapes the characteristics of grapes and, by extension, the wine made from them. The microbial influence on terroir Recent research has highlighted the role of microorganisms – such as bacteria, yeasts and fungi – in contributing to the unique character of a vineyard’s terroir. These microbes affect everything from nutrient availability in the soil to the fermentation process that turns grape juice into wine (Gilbert et al ., 2014). In fact, different regions have distinct microbial communities that can influence wine flavour and aroma, adding another layer of complexity to terroir (Knight et al ., 2015). Microbes like Proteobacteria and Acidobacteria dominate vineyard soils, while fungi such as Cryptococcus are also

Rising temperatures and their impact on grapes As global temperatures continue to climb, the effect on grape ripening is unmistakable. With warmer temperatures, grapes mature faster, leading to earlier harvests. While this might sound like a good thing, it can drastically alter the balance of sugars, acids and tannins in the fruit. Warmer climates may increase the sugar content, boosting alcohol levels in wine, but potentially reducing the complexity of its flavours, particularly in cooler regions like Burgundy or parts of Germany. The nuanced flavour profiles that define some of the world’s most famous wines could be at risk (Gladstones, 2011). Water woes – droughts and excess rainfall Changes in precipitation patterns present another challenge. In key wine-growing regions like Southern Europe, California, South Africa and Australia, prolonged droughts are becoming more frequent. This means that vineyards might have to rely more heavily on irrigation. However, in areas where water resources are already scarce, disputes over water rights could become more common, and winemakers may be forced to adopt water-saving practices like dry farming or alter their vine training techniques to conserve moisture. Conversely, some regions may experience excess rainfall, especially during the critical harvest period. Too much rain increases the risk of diseases like mildew and rot, potentially devastating vineyards. Additionally, it can dilute the grapes, weaken flavours and reduce the quality of the final product (Gladstones, 2011). Extreme weather – frost, hail and heatwaves More extreme weather events, from hailstorms to frost and heatwaves, add to winemaking’s unpredictability. Late frosts in spring can destroy delicate buds and emerging shoots, while hailstorms can wipe out entire vineyards in minutes. Heatwaves present another severe threat. Vines exposed to excessive heat may experience stress, leading to early ripening and fruit shrivelling. This has led many winemakers to adjust their vineyard practices, using techniques like canopy management to provide more shade or moving vineyards to more excellent areas at higher altitudes to mitigate heat risks (Gladstones, 2011). Adaptation strategies in the face of climate change The wine industry is developing several strategies to cope with these climate-induced challenges. One approach is shifting grape varieties. For instance, warmer regions might begin planting more heat-resistant varieties like Grenache, Mourvèdre, or Syrah, which can thrive in higher temperatures while still producing high-quality wines. Vineyard management practices are also evolving. Growers can reduce the impact of rising temperatures by changing planting density, adjusting the direction of vineyard rows and altering pruning methods. Technological innovations, such as smart irrigation systems and climate forecasting tools, are helping winemakers adapt to changing conditions (Gladstones, 2011).

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TECHNICAL YEARBOOK 2025