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Plum pox virus (PPV) isolates from stone-fruit trees (plums, myrobalans, apricots and peaches) from orchards and gardens were characterized. To characterize their biological properties, several PPV isolates were transmitted by chip budding to GF 305 seedlings and mechanically to selected herbaceous test plants. The isolates differed in severity of infection, host range and symptomatology. A subgroup differentiation of 43 isolates from 22 localities of western and middle Slovakia was accomplished using reverse transcription-polymerase chain reaction (RT-PCR), immunocapture RT-PCR (IC-RT-PCR) and restriction analysis. These assays confirmed the presence of isolates belonging to PPV-M and PPV-D subgroups. PPV-M and PPV-D isolates were almost equally represented in tested samples. Tests of subgroup variability of PPV isolates from infected tolerant plum cultivars showed great predominance of PPV-M isolates.

In this report, the plum pox virus (PPV) spread from the point of view of agroclimatical conditions on the territory of Slovakia is analysed. The worst condition for the PPV spread was found in a warm macroregion. The air temperature sum in this macroregion during vegetative period ranged from 2400 to 3100 degrees C. The worst condition for the PPV spread was found in dry subregions of the macroregion. These were defined by differences between potential evapotranspiration and rainfall sums which ranged from 50 to 150 mm during summer months (from June to August). The decrease in air temperature sums and the increase of moisture in the environment as well as the severity of winter period was found to support the occurrence and spread of PPV.

Leaf tissues of stone fruit trees (plum, apricot, peach and myrobalan) carrying symptoms of plum pox virus (PPV) infection and of peach GF 305 seedlings and Nicotiana benthamiana infected experimentally with PPV were assayed for PPV by polymerase chain reaction (PCR). The expected 243 bp PCR products were subjected to restriction fragment length polymorphism (RFLP) analysis with restriction endonucleases AluI and RsaI. All of the PCR products contained the AluI site. The RsaI restriction profiles of the PCR products demonstrated the prevalence of PPV-M subgroup in the tested samples from western Slovakia.