Common ragwort (Senecio jacobaea) is a widespread biennial species native to the British Isles. It contains toxins which are potentially lethal if ingested by grazing animals, and is a specified weed under the Weeds Act 1959. Where no threat is posed to livestock, ragwort forms part of the natural British flora and is a beneficial plant that supports a wide range of insects. During June 2007, plants of S. jacobaea growing in a field in Egham, showed symptoms of little leaf, chlorosis, and proliferation of axillary shoots. Infected plants frequently had fewer stems and reduced numbers of flower heads. The distribution of disease was patchy, with approximately 60% of plants displaying obvious symptoms. DNA sequencing showed that the pathogen had the highest similarity (96%) with the phytoplasma associated with yellows of Festuca arundinacea from Lithuania (GenBank Accession No. DQ640504) of the 16SrI group, 'Candidatus Phytoplasma asteris'. This is thought to be the first record of a phytoplasma infecting S. jacobaea in the UK.
Reeder, R.; Arocha, Y. &#8216;Candidatus Phytoplasma asteris&#8217; identified in Senecio jacobaea in the United Kingdom. Plant Pathology (2008) 57 (4) 769-769. [DOI: 10.1111/j.1365-3059.2008.01849.x]