A severe outbreak of flavescence doree on Sangiovese in vineyards in Valtenesi (Lombardy)

During 1997 a few cases of grapevine yellows were observed in Sangiovese vineyards in Valtenesi, located on the south-western coast of Lake Garda, Lombardy, Italy. The disease became more frequent during 1998 and 1999, causing severe economic damage. Samples were taken for analysis in September and October 1999. The results indicated that the symptoms were typical for red grape cultivars, with frequent cluster drying off; disease incidence varied from 60 to 90%; in all the examined vineyards, high numbers of Scaphoideus titanus insects were found; and molecular analysis (PCR and RFLP) of leaf samples taken from diseased grapevines showed the presence of the flavescence doree phytoplasma (group 16SrV-C) in most cases. The Bois Noir phytoplasma (group 16SRXII-A) was rarely found.