Aroma chemical markers of Durello wines from different vintages and origins: a case study

The ripening of grapevine berries encompasses complex morphological and physiological processes, especially at veraison. Berry shrivel (BS) is a ripening physiological disorder affecting grape berries with visible symptoms appearing short after veraison. The main symptoms of BS are a strong reduction in sugar accumulation, inhibited anthocyanin biosynthesis and high pH values. The most popular red grape cultivar in Austria “Blauer Zweigelt” (Vitis vinifera L.) is specifically prone to develop the BS ripening disorder and up to date a no specific cause or causes could be identified. Recently omics approaches have identified and characterized key processes during grapevine ripening. Among them a small subset of genes, called SWITCH, have been described as markers for the onset of the ripening process in fruits.

In Franconia, the northern part of Bavaria in Germany, climate change, visible in earlier bud break, advanced flowering and earlier grape maturity, leads to a decrease of traditionally cultivated early ripening aromatic white wine varieties as Mueller-Thurgau (30 % of the wine growing area) and Bacchus (12 %). With the predicted rise of temperature in all European wine regions the conditions for white wine grape varieties will decline and the grapes themselves will lose a part of their aromatic and fruity expression. Variety change towards the cultivation of later ripening white wine varieties is a very expensive and long-term process, and must be accompanied by special marketing efforts.

Esca, one of the main grapevine trunk diseases, is a complex and poorly understood disease. Phaeoacremonium minimum and Phaeomoniella chlamydospora, two of the main pathogens associated to this disease, are thought to be responsible for the first trunk infections. Little is known concerning grapevine trunk defenses during pathogen infection.

Winter pruning is today the longest operation for hand workers in the vineyard. Over the last years, mechanical pruning practices have become popular in southern France vineyards to respond to competitiveness issue especially for the basic and mid-range wine production. Wine farmers have developed different vineyard management techniques associated with mechanical winter pruning. They sought to be precise or not to control the buds number per vine.

Effects of climate change on viticulture systems and winemaking processes are being felt across the world. The IPCC 6thAssessment Report concluded widespread and rapid changes have occurred, the scale of recent changes being unprecedented over many centuries to many thousands of years. These changes will continue under all emission scenarios considered, including increases in frequency and intensity of hot extremes, heatwaves, heavy precipitation and droughts. Wine companies need tools and models allowing to peer into the future and identify the moment for intervention and measures for mitigation and/or avoidance. Previously, we presented conceptual guidelines for a 5-stage framework for defining adaptation strategies for wine businesses. That framework allows for direct comparison of different solutions to mitigate perceived climate change risks. Recent global climatic evolution and multiple reports of severe events since then (smoke taint, heatwave and droughts, frost, hail and floods, rising sea levels) imply urgency in providing effective tools to tackle the multiple perceived risks. A coordinated drive towards a higher level of resilience is therefore required. Recent publications such as the Australian Wine Future Climate Atlas and results from projects such as H2020 MED-GOLD inform on expected climate change impacts to the wine sector, foreseeing the climate to expect at regional and vineyard scale in coming decades. We present examples of practical application of the Climate Change Adaptation Framework (CCAF) to impacts affecting wine production in two wine regions: Barossa (Australia) and Douro (Portugal). We demonstrate feasibility of the framework for climate adaptation from available data and tools to estimate historical climate-induced profitability loss, to project it in the future and to identify critical moments when disruptions may occur if timely measures are not implemented. Finally, we discuss adaptation measures and respective timeframes for successful mitigation of disruptive risk while enhancing resilience of wine systems.