OCCURRENCE AND DISTRIBUTION OF PLUM POX VIRUS IN CROATIA

Abstract

In effort to determine the incidence and distribution of plum pox virus (PPV) in stone fruit orchards throughout the country, a survey was carried out in the year 2004. Solitary Prunus trees found as a part of spontaneous vegetation were also included in this study. After visual inspections, samples were taken mostly from trees showing sharka symptoms. Total of 367 samples were ELISA tested by using universal and specific (PPV-D, PPV-M, PPV-EA and PPV-Ch) antibodies. Over fifty percent (54, 49%) of these samples were PPV positive. The incidence of PPV in 253 symptomatic samples was 69, 56% while reaching 21, 05% in symptomless ones. Fifty samples (33 symptomatic and 17 symptomless) were retested using IC/RT-PCR and, in total, 60% was positive (78, 78% symptomatic and 23, 52% symptomless). PPV is present in every Croatian stone fruit growing region, with the exception of some isolated zones in the central part of the country (Lika). However, its incidence varies with respect to tested Prunus species. In continental northeastern part of Croatia, plum is widely infected, while infected peach samples can be found only in very restricted part of this region. Infected sweet cherry trees are mainly present in the northern part of the country. Apricots that harbor PPV, on the other hand, have been found only along the Adriatic cost. The presence of PPV-M strain has been confirmed by using serological and IC/RT-PCR/RFLP assays in all geographical regions. PPV-D strain has been confirmed only in Istra (northern coastal part) and Međimurje (northern continental part). PPV-M strain has been found in plum, peach, nectarine, sweet cherry and in spontaneous P. myrabolana trees. PPV-D strain has been confirmed only in peach and P. myrabolana. These findings, in conjunction with aphid populations monitoring, will be used in devising protection measures and strategies for PPV control.