Long term analysis of the link between practices and vineyard decline in relation to abiotic factors

Vineyard decline is one of the main challenges viticulture now faces, especially in the current context of climate change. While decline is often attributed to grapevine trunk diseases and climate change, it also involves a myriad of other interconnected factors, including agricultural practices, whose role in decline remains unclear. This study explored for the first time how various planting conditions and agricultural practices implemented over an extended period of time affect the intensity and dynamics of decline. We analysed a large dataset obtained from 107 plots in the Cognac wine-growing region in western France from 1988 to 2018. The dataset included data on soil and climate conditions, genetic material at planting, annual agricultural practices, and information on annual mortality and yield. This study comprised six steps: dataset building, characterisation of decline categories, selection of explanatory variables to be studied, creation of plot trajectories based on agricultural practices, linking of decline categories and plot trajectories, and analysis of plot characteristics and practices. Using data from 43 plots and 58 variables, we showed that vineyard plots can be classified into three stages of decline depending on the dynamics and intensity of mortality and yield dynamics. We then established 11 trajectories over the plot lifespans (16 to 30 years). A detailed analysis of these trajectories revealed that plots associated with certain trajectories were more subject to decline, which helped us identify strategies that could limit or even prevent decline. We concluded that preventing decline requires adopting an integrated approach from planting to grubbing up, finding the right match between genetic material and soil–climate conditions, ensuring optimal water management, and managing potentially competing vegetation, like cover cropping. By identifying key practices over the vineyard lifespan, this study opens up new avenues for preventing decline by putting the focus on vigour management, water and mineral status of the plant.