Incidence of viruses infecting grapevine varieties in Istria (Croatia)

The incidence of viruses infecting local grapevine (Vitis vinifera L.) varieties, including six widespread cultivated and 12 endangered varieties in Istria (Croatia), was determined. A total of 781 samples of 18 autochthonous varieties, collected on 41 locations throughout the Istrian Peninsula, were tested by double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) for the presence of four grapevine viruses. Infection with nepoviruses Arabis mosaic virus (ArMV) and Grapevine fanleaf virus (GFLV), and closteroviruses Grapevine leafroll-associated viruses 1 and 3 (GLRaV-1 and GLRaV-3) were surveyed over four years (2003-2006). Viruses GFLV, GLRaV-1 and GLRaV-3 were found at almost all investigated Istrian locations, and most varieties were infected. A total of 82.2% of ELISA-tested vines were infected, thereof 69.0% with one and 31.0% with more viruses. GLRaV-3 was the most prevalent virus (69.1%) followed by GFLV (23.9%) and GLRaV-1 (17.2%). ArMV was not detected. The incidence of detected viruses at locations in the area of intensive viticulture production (91.8%) was higher than at geographically isolated locations with extensive viticulture production (48.3%). A high virus incidence (66.1-95.8%) was observed among widespread cultivated varieties, whereas 47 out of 76 tested samples of endangered varieties were infected. Results of this extensive grapevine virus survey in Istrian region of Croatia demand the establishment of efficient virus control strategy.