Role of wild Prunus species in the epidemiology of European stone fruit yellows

Several uncultivated trees of the species Prunus spinosa , P. cerasifera and P. domestica , sampled both adjacent to European stone fruit yellows (ESFY)‐infected orchards and in isolation from cultivated stone fruit plants, were found to be infected by ESFY phytoplasma. These species were also colonized by Cacopsylla pruni , vector of the ESFY agent. In contrast, uncultivated species of Prunus avium , P. cerasus and P. mahaleb hosted neither the pathogen nor the vector. Insect‐ and graft‐transmission trials of ESFY phytoplasma conducted under controlled conditions confirmed the data obtained in the field. The role played by the wild Prunus species is discussed and appears to be fundamental in the epidemic cycle of the disease.