First report of ‘Candidatus Phytoplasma ulmi’ in the United Kingdom
The NPPO of the United Kingdom recently informed the EPPO Secretariat of the first record of ‘Candidatus Phytoplasma ulmi’ (EPPO A1 List, initially listed as ‘Elm phloem necrosis’*) on its territory. Ulmus hybrid plants (Ulmus chenmoui x [(Ulmus glabra x Ulmus minor) x Ulmus minor] clone Morfeo) showing unusual symptoms (dwarf shoots) were noticed by the grower. Samples were taken and ‘Ca. Phytoplasma ulmi’ was detected and identified by sequencing in January 2014. These infected plants were derived from 10 mother plants which had been imported from Italy in 2010/2011. Investigations showed that more than 500 trees had been propagated from the original 10 mother plants, and these potentially infected plants are now being traced and destroyed. As of February 2014, 4 locations having received these plants have been identified in the Central and Southern parts of the UK.
The pest status of ‘Candidatus Phytoplasma ulmi’ in the United Kingdom is officially declared as: Transient, actionable, under eradication.
* Note: Although phytoplasma diseases observed in elms in North America (elm phloem necrosis) and in several European countries (elm yellows) have different symptomatologies, the phytoplasmas associated with them are very closely related if not belonging to the same species ‘Ca. Phytoplasma ulmi’. Therefore the inclusion of this pathogen on the A1 List (absent from the EPPO region) might need to be reconsidered (see also EPPO RS 2009/217).
NPPO of the United Kingdom (2014-02).