Spread of European stone fruit yellows in Piedmont (northwestern Italy) and presence of Cacopsylla pruni Scopoli in plum and apricot orchards

Abstract: In recent years, high percentages of declining plants showing symptoms ascribable to the European stone fruit yellows (ESFY) disease were recorded in plum and apricot orchards in Piedmont, north western Italy. Since 2006, visual inspections were carried out in dozens of orchards to assess the incidence of symptomatic plants in early spring (premature budbreaks) and late summer (yellowing and leafroll). Surveys with yellow sticky traps and beating tray were carried out from the beginning of March until the beginning of June to monitor the presence of Cacopsylla pruni and other possible vectors in the orchards and in the surroundings on wild Prunus species. The presence of “Candidatus Phytoplasma prunorum” in plum and apricot trees as well as in the insects was ascertained by PCR and RFLP analyses. The very low C. pruni population density recorded and the presence of “Ca. Phytoplasma prunorum” in recently planted orchards (1 year old) suggest an early infection possibly occurring in the nurseries.