Forestry Commission scientists have confirmed that Phytophthora lateralis, a pathogen that kills trees’ roots, has infected several trees in a shelter hedge on an industrial estate. The commission would not confirm the precise location while it deals with the disease.
The trees will be felled and disposed of safely and the site is subject to biosecurity measures to prevent spreading the disease particularly in contaminated soil, felling equipment and other tools.
Until recently, P. lateralis was mostly known in the western states of the USA and Canada, but outbreaks have also been recorded recently in Scotland, Northern Ireland, France and The Netherlands. The pathogen has also been reported recently from Taiwan on yellow cedar.
Forestry Commission plant health head John Morgan said:
"It is very worrying to find this destructive tree pathogen so far from previous cases in Scotland and we are working hard with colleagues in Fera to contain the disease quickly and try and trace where it came from. Our surveillance teams are actively looking for signs of the disease during helicopter surveys.
"Its main victim is Lawson cypress, not a very significant forestry tree, but very popular in parks, gardens, churchyards and crematoria. We are asking people working around trees, particularly arboriculturists and those who manage parks and gardens to be particularly vigilant for signs of the disease. If they are called to examine or fell a dead or dying Lawson cypress and are suspicious of the causes, we ask they follow biosecurity guidance published on our website.
"Experience in Scotland and Northern Ireland leads us to anticipate more findings in England. If the disease becomes established it could also be very serious for the ornamental plant industry because Lawson cypress - and its various colourful varieties - is one of the most important conifers in the ornamental plant trade."
Yesterday, Environment Secretary Caroline Spelman launched The Tree Health and Plant Biosecurity Action Plan, a new Government drive to combat the exotic pests and diseases threatening the health of trees in this country.
Symptoms of P. lateralis infection on Lawson’s cypress include the foliage initially appearing a lighter olive-grey in colour than that of healthy trees, then withering and turning reddish-brown as foliage dies. Also, as the infection extends from the roots and root collar up the stem, it kills the inner bark and the entire tree dies as the stem is girdled.
Anyone concerned that their Lawson cypress trees might have the infection should contact either:
Forestry Commission’s Disease Diagnostic & Advisory Service
Tel: 01420 23000
By post to Disease Diagnostic & Advisory Service, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH
Fera Plant Health and Seeds Inspectorate
Tel.: 01904 465625
Notifications should include as precise a description of the location as possible – an Ordnance Survey or GIS reference is ideal, otherwise a full postcode is helpful.
Photographs clearly showing the symptoms are also welcome to aid diagnosis.