OCCURRENCE AND DISTRIBUTION OF PLUM POX VIRUS IN CROATIA

In effort to determine the incidence and distribution of Plum pox virus (PPV) in stone fruit orchards throughout the country, a preliminary survey was carried out in the year 2004. After visual inspections, 367 samples, mostly from trees showing sharka symptoms, were taken for ELISA testing by using universal and specific (PPV-D and PPV-M) antibodies. Over forty percent (44%) of these samples were PPV positive in initial screening (about 70% of symptomatic and 21% of symptomless). Fifty samples were retested using IC-RT-PCR, and in total, 46% was positive (58% symptomatic and 24% symptomless). PPV is present in all Croatian stone fruit growing regions, with the exception of some isolated zones in the central part of the country; however, its incidence varies with respect to tested Prunus species. The majority of positive samples were found infected by M strain. These included 9 plum, 1 spontaneous P. myrabolana, 5 peach, 1 nectarine and 2 sweet cherry samples distributed all over the country. D-strain was characterized in 1 peach sample and 4 plums clustered exclusively in the far eastern and western parts of Croatia. Two of these plums harbored both PPV strains.