First report of Phytophthora lateralis in the United Kingdom
The NPPO of the United Kindgom recently informed the EPPO Secretariat of the first record of Phytophthora lateralis (EPPO A1 List) in Scotland. In October 2010, dieback and mortality of Chamaecyparis lawsoniana trees was noticed at the Balloch Castle Country Park. This park is an important historical site located within the Loch Lomond and Trossachs National Park. Affected trees were predominantly mature (approximately 70-80 year old) and showed symptoms which varied from foliage dieback of discrete patches of the crown to mortality. Some of the declining Chamaecyparis trees were also showing resin bleeding on the stems and branches, which apparently originated at branch junctions or wounds. Root and stem samples were taken from 4 trees and tested. Laboratory tests (lateral flow device for Phytophthora spp., PCR and sequencing, morphology) confirmed the presence of P. lateralis.
During winter, further investigations on the site were hampered by bad weather conditions (heavy snow). However, by February 2011 a total of 90 symptomatic, including 10 confirmed positively by laboratory tests, infected C. lawsoniana had been identified and these were all felled and destroyed by burning by 23 February. A single C. lawsoniana was confirmed as infected by P. ramorum (EPPO Alert List), only the second specimen of this species found infected with P. ramorum in the UK. A Rhododendron plant was found positive for P. ramorum and has been destroyed. P. cinnamomi was also found infecting Taxus baccata on the site. These infected plants have also been voluntarily destroyed. Investigations are continuing at the site and surveys of all C. lawsoniana within 3 km of the park will be carried out in the spring, in order to determine future management measures. For the moment, it has not been possible to identify the source of introduction of P. lateralis into Scotland but it is suspected that the pathogen may have been present in this park for 5 to 10 years. Precautions are being taken to prevent any further spread of the pathogen (i.e. prohibition to move plant material from the infected site including composted material, disinfection of all machinery and equipment used for tree destruction, warning notices for visitors and disinfectant foot mats at all exit points of the park).
The pest status of Phytophthora lateralis in the United Kingdom is officially declared as: Present, under eradication.
Sources
NPPO of the United Kingdom (2011-03).