Grapevine dieback is a wasting syndrome characterized by a decline in grape production, sometimes leading to premature death ot the wine stock. It does not have a unique cause, but several factors are know to be possibly causing and/or facilitating it (biological pressure from pests and annual diseases, climatic and nutritional stresses, technical management, socio-economical constraints). It is frequently, but not always associated with wood diseases, but it remains unclear whether these diseases are responsible for the dieback or act as opportunistic parasites. Viticulture is the most valuable French agricultural sector, producing 4.7 billion liters wine every year, i.e. 16% of the global production. Grapevine dieback causes a loss of 4.6 hL of wine par ha every year in French vineyards. French National Agency of Sea and Agricultural Products (France AgriMer) together with actors of the french wine sector built a plan to understand grapevine dieback and investigate solutions through four main actions (www. plan-deperissement-vigne.fr). One of them is dedicated to research on this syndrome, in interaction with the wine sector. TraDeVi is one of the nine research projects supported by this plan in 2018. Project outline: Previous studies on dieback mainly took into account wood diseases, and lead to the conclusion that this was not sufficient to understand the dieback occurence and dynamics. This three-year project aims at understanding the facilitating and decisive factors leading a vineyard to dieback. To understand how and why a vineyard undergoes dieback, we study the history and present state of normally producing vs declining vineyards. The studied parameters include physical and biological soil parameters, vine physiological variables such as water and nutrients uptake and partitioning, yield and yield components dynamics and technical management. We will test the feasibility of using forestry tools such as dendrochronology to reconstruct the growth history of wine stocks and elucidate the initiation of growth decline. The indicators and hypotheses proposed will be tested in producing vineyards of different locations in south of France.