Phytophthora ramorum has been found in a tree in the same country park in Scotland where Phytophthora lateralis was confirmed in Lawson’s cypress trees late in 2010.
It was the first time that P. lateralis had ever been identified in Britain, and now Forestry Commission plant pathologists have also confirmed the presence of its close relative, Phytophthora ramorum, in a Lawson’s cypress tree and rhododendron at the same site.
The site is Balloch Castle Country Park on Loch Lomondside in West Dunbartonshire, and P. ramorum has also been confirmed in rhododendron at the park.
The park is only the second site in Scotland where P. ramorum has been found in trees, although it has previously been found in other plants in Scotland. However, P. ramorum infection has been the cause of the emergency felling of more than 2 million Japanese larch trees in South-West England, Wales and Northern Ireland, as well as some in the Republic of Ireland, in an effort to prevent the pathogen from spreading further afield.
The Commission’s Forest Research agency was first alerted late in 2010 when about 80 Lawson’s cypress trees and 27 common yew trees at the park showed signs of decline and ’dieback’ and appeared to be dying. Their investigations confirmed that P. lateralis was involved in at least some of the cypress trees’ condition.
Then further investigations revealed that at least one of the cypress trees and a rhododendron bush are infected with P. ramorum.
Both pathogens are ’quarantine’ organisms, meaning that plant health authorities such as the Forestry Commission are required by law to take statutory measures to contain or eradicate them.
Roddie Burgess, Head of the Forestry Commission’s Plant Health Service, said,
"These are very worrying developments, because both of these pathogens cause serious plant and tree diseases.
"We are working closely with the park’s owner, West Dunbartonshire Council, on measures to reduce the risk of the pathogens being spread into the wider environment. Unfortunately this means that a significant number of trees have to be felled, because P. ramorum spores in particular can be spread considerable distances in mists and moist air currents. Sadly, the only way to prevent this is to destroy the living plant material on which it depends to produce the spores.
"Anyone who has any species of cypress, larch or rhododendron on properties in the area is asked to check them carefully for signs of dying foliage and to report suspicious symptoms to us. We are also carrying out our own surveys in the area."
