Wood discoloration and decay in grapevines with esca proper and their relationship with foliar symptoms

From two Italian vineyards affected with esca proper, vineyard A (Borghi, FC, Emilia-Romagna) and vineyard B (Controguerra, TE, Abruzzo), located in different wine-growing areas and with different cultivars, 165 vines were collected that had shown the leaf symptoms of esca proper in the years before. Each vine was inspected and the cubic volume of the main symptoms in the trunk was measured: discoloration, including the various forms of dark necrosis, and decay. In each vine of both vineyards the extent of wood deterioration was compared with the severity of the leaf symptoms recorded in the years before the vines were cut down. The existence of a correlation between discoloration and decay in the wood colonisation process was explored. No correlation was found between the severity of the wood deterioration and the severity of the leaf symptoms. The typical leaf symptoms were found also on vines that had only wood discoloration without any decay. There was no correlation between wood discoloration and decay in vineyard A in which the vine wood was more degraded, with a greater incidence of decay. In vineyard B, however, in which the incidence of decay was less, a correlation between decay and discoloration was potentially found.