Evaluation of Plum Pox Virus sensibility on different stone fruit varieties in Emilia-Romagna region (Italy)

Between 2003 and 2011, about 200 stone fruit varieties were inoculated by chip budding with PPV M strain, grown in a screen house and then surveyed for symptom expression on leaves, flowers and fruits. During the following season in particular 126 peach and nectarine, 45 apricot and 28 plum varieties and seedlings (from breeding programs) under evaluation were assessed in the present work. A large number of varieties showed discoloration and mottling on the young leaves in spring; furthermore all peach and nectarine selections with rosaceous flowers appeared infected by PPV with strong symptoms on petals. Many peach and apricot cultivars and seedlings, but only one plum variety, presented fruit deformations with typical rings and mottling. Only a few accessions (2 peaches and 10 apricots) belonging to “ancient” germplasm or to seedlings did not appear affected by typical symptoms on leaves and fruits, nor were positive to PPV by ELISA and Real Time RT-PCR assays. These experimental data revealed high sensibility of stone fruit germplasm to PPV-M as confirmed by the information gathered in the Emilia-Romagna region, by inspectors of the local Plant Protection Service. In particular during 15 years of orchards surveys 36 varieties of apricot, 37 of plum, 102 of nectarine and 83 of peach (both traditional and promising varieties) were infected, showing typical symptoms, as a result of the natural PPV spread in the field.