Flavescenza dorata in cv Barbera e Nebbiolo: incidenza, risanamento e suscettibilità al patogeno

During the period 2008-2010 two vineyards, one of cv Barbera and the other of cv Nebbiolo, were inspected for Flavescence Dorée (FD) presence and incidence. During the surveys, leaf samples were taken at the end of May, July and September from vines with phytoplasma symptoms, and further analysed by PCR. FD was by far the most important phytoplasma associated to the disease (only few vines were double-infected with Bois Noirphytoplasma). Fifty-one vines in 2008 and 130 in 2010 (out of 8000) were infected in the Barbera vineyard. Twenty-six in 2008 and 30 in 2010 (out of 1250) were infected by FD in the Nebbiolo vineyard. More than half of the 51 FD-Barbera vines in 2008 stably recovered in the following two years, while only one third of the 26 FD-Nebbiolo vines recovered in the same time frame. When the FD titer was measured by quantitative real Time PCR in both varieties over the season, a higher titer of FD was estimated in Barbera compared to Nebbiolo. Consistently, the symptoms associated to the disease were more serious on Barbera, especially at the beginning of the growing season when Barbera displayed a dramatic dwarfing of the shoots. We conclude that Barbera is more susceptible compared to Nebbiolo, but it shows a higher attitude to recover from the disease