The occurrence of 'Candidatus phytoplasma rhamni' in Rhamnus cathartica L. without symptoms

Common buckthorn, Rhamnus cathartica L., is a small tree or shrub of Eurasian origin that has become invasive in North America. A survey was conducted during 2010 to evaluate occurrence of buckthorn witches' broom (BWB) disease symptoms induced by Candidatus Phytoplasma rhamni' in the native range of R. cathartica. The distribution of phytoplasma-infected trees was identified over a large expanse of Europe, from south-west Switzerland to north-east Serbia. Although 25% of analyzed buckthorn trees were infected with phytoplasma (34 out of 133 plants), all plants were symptomless, indicating a commensal relationship between the phytoplasma and its plant host without negative effects which would lead to disease development