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RESEARCH PRODUCT

Impact du changement climatique sur l’oïdium de la vigne : cas de la Champagne

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Powdery mildew, one of the most widespread grapevine disease, causes damage to the plant foliage, reduces yields and altersquality of grapes. This fungus development is strongly controlled by climate conditions and viticulture requires in many regionslarge quantities of pesticides for disease control. Projecting the impacts of climate change on these disease and developinga better understanding of future disease risk is crucial, given the increasing societal pressure for pesticide reduction andsustainability. This study focused on (i) the elaboration of an empirical model that establishes links between monthly climate dataand annual powdery mildew pressure in Champagne and (ii) the use of this empirical model to simulate the evolution of diseasepressure using simulated climate data (1976-2100). The disease pressure database represents the powdery mildew observedplots percentage with leaves and grapes symptoms expression at different phenological stages. The data was studied across the2004-2018 period and it included 200 Chardonnay plots in Champagne. Monthly climate indices (temperature and precipitation)were tested using multiple linear regressions in order to explain the vineyard observed pressure at different phenological stages.The best linear multiple regression model simulates the percentage of impacted plots observed on the 1st of July based on April’smean minimum temperatures and May’s cumulated precipitations. The 21st century disease risk was projected with the CMIP5RCP8.5 scenario temperature and rainfall data from 18 GCMs (General Circulation Models) which were statistically downscaledand debiased to match a daily 8 km target resolution over the 1976-2100 period. These data were then used to fed the retainedpressure model. The increase in future climate temperatures and the small decrease in precipitation lead to a low simulatedpowdery mildew pressure over Champagne for the 21st century.