Occurrence, distribution and epidemiology of Grapevine Yellows in Spain

The main viticultural production areas in Spain were surveyed in 1994, 1995 and 1996 for the occurrence and incidence of Grapevine Yellows diseases as sociated to phytoplasmas. Samples from 300 plants showing symptoms of phyto plasma infection were collected from grapevine fields in the Spanish region s of Aragon, Catalonia and Navarra and analysed by PCR with specific primer s for a non-ribosomal DNA of stolbur/Bois Noir (BN) and of Flavescence dore e (FD) phytoplasma. Nested PCR with universal primers P1/P7 and fU5/rU3 was also used. In the survey conducted in 1994 and 1995 only BN/stolbur phytop lasma was detected. The incidence of symptomatic plants was low in five plo ts of Catalonia from 3% to 18% in 1994 and 1995, respectively, and high in two plots of Navarra, from 60% to 80%. In the survey conducted in 1996 the incidence of symptomatic plants in Catalonia increased (6-80%) due to the p resence of FD in five plots in the Northeastern Catalonia. An epidemiologic al study was carried out in two BN-affected plots of two regions from 1994 to 1997, with the evaluation of potential vectors and of host plants. The s tolbur phytoplasma was found in individuals from different insect species b elonging to the families Cicadellidae and Delphacidae. Some wild plants nat urally infected with stolbur phytoplasma around the infected grapevines wer e: Convolvulus arvensis, Lavandula officinalis, Polygonum convolvulus, Sola num nigrum, and Thymus officinalis. The incidence of the disease in one BN- infected grapevine plot increased from 3.4% in 1994 to 18.40% in 1997.