Effects of grapevine cultivar, rootstock and clone on esca disease

Esca is one of the main causes of reduction of production, plant decline and death in vineyards of most viticultural areas of the World. We determined the foliar esca symptoms on a range of grapevine cultivars in three centraleastern Italian vineyards during summer 2008, characterized by conducive conditions for the disease. In vineyard AP1, the incidence of symptomatic plants was recorded for 67 Vitis vinifera cultivars. Among white-berried cultivars, Passerina, Sauvignon blanc, Manzoni bianco, and Riesling, had highest incidence of symptomatic plants (28–35 %), while cvs. Chiapparù, Grechetto, Perdea, Verdicchio, Fiano and Pinot blanc had lowest (0–5 %). Among red-berried cultivars, Rebo had highest incidence of symptomatic plants (>35 %), with lowest for cvs. Lacrima, Brugentile, Sirah, and Limberger (0 %), followed by Gallioppo, Merlot, and Nebbiolo (<5 %). However, mean values of symptomatic plants among red and white cultivars were similar. The six cultivars monitored in vineyard AP2 confirmed this cultivar susceptibility ranking. Furthermore, in vineyard AN1, incidence of esca symptoms on seven cultivars grafted onto different rootstock was recorded. Cvs. Fiano and Sauvignon grafted onto SO4 showed higher disease incidence than combinations with 1103P. This result can be ascribed to the higher drought resistance of 1103P as compared to SO4, supporting the hypothesis that esca symptoms occur mostly in stressed plants. Significant differences in the symptom expression were recorded just among clones of Sauvignon, while they were not found in Chardonnay, Riesling and Pinot blanc. Our data give useful information for growers in planning cultivar/rootstock combination choice for new vineyards, and can provide an idea of possible evolution of esca along time in an already established vineyard.