Résumé
The Grand Est region is the leading region for the production of damson (Prunus domestica subsp. insititia) andmirabelle (Prunus domestica subsp. syriaca) plums. Damson production is threatened by sharka, caused by the plum pox virus (PPV), which is spreading in this region and controlled by visual inspection of the orchards and removal of symptomatic trees. In contrast, only very few symptoms have been reported on mirabelle leaves and fruits. Therefore, sharka is not surveyed on this species, despite the lack of scientific evidence on its susceptibility to the main PPV strains and on its potential role in sharka epidemics.We combined orchard surveys with experimental assays under controlled conditions (i) to estimate the prevalence of PPV in mirabelle orchards and (ii) to evaluate the susceptibility of two mirabelle cultivars (P1725 and P1510) to PPV-M, PPV-D and PPV-Rec isolates after graft- and aphid-inoculation in comparison with a susceptible damson cultivar (P3066). The presence of PPV was assessed by DAS-ELISA in 7102 leaf samples collected from 4481 trees in 53 mirabelle orchards. PPV was detected in 15% of the orchards, but the overall prevalence was very low (1.7%). The virus was detected mainly in rootstock suckers (2.6% among tested suckers) and occasionally in mirabelle leaves (0.25% of all mirabelle samples tested), on which no symptoms of sharka were observed. Experiments showed that both of the tested mirabelle cultivars were susceptible to the three PPV strains regardless of the inoculation method, with typical PPV symptoms on the leaves. Key parameters of the infection cycle (transmission rate to test plants, incubation period, viral load, and retransmission rates by aphids from PPVinfected plants) showed that the susceptibility of the mirabelle cultivars is lower than that of the damson cultivar and depends on the PPV strain. Apparent discrepancies between survey and experimental results are discussed.