Epidemiological surveys on esca disease in Umbria

During 2006 and 2007 surveys were carried out in a 25-year-old experimental vineyard of the University of Perugia (Umbria) in order to determine the incidence of esca on ten grapevine cultivas (Caberbet sauvignon, Grechetto, Sangiovese, Trebbiano toscano, Pinot bianbco, Trebbiano spoletino, Ciliegiolo, Montepulciano, Chardonnay and Merlot) growing in the same conditions, to identify the pathogens associated with the disease in Central Italy and to verify under what climatic conditions they release spores. Visual examination showed that all the cultivars were susceptible to esca; the incidence of the disease increased during summer, reaching the highest values in the end of August. In both years the ncidence of the disease was higher on Cabernet sauvignon, Sangiovese and Trebbiano toscano ehile it was lower on Montepulciano. Only Phaeomoniella chlamydospora (Pch) was isolated from vines sampled in the filed. Isolation carried out on different cross-sections of the plants showed that there were no signifincant differances among the frequencies of Pch isolation form rootstock, bottom, centre and apex. Moreover, frequency of isolation was not significantly different from plants that showed esca symptoms and plants that did not show symptoms. From asymptomatic vines, there were no significant differences on the frequency of isolation from plants harvested close to vines that showed externalò esca symptoms and apparently healthy plants. among the fungal agents of esca only spores of Pch were captured. The airborne spores were obtained from March to December 2007. Spore release was influenced by climatic parameters (rain and temperature).