A deadly plant disease previously unknown in England has been found in Devon killing Lawson Cypress trees that are commonly found in parks and gardens.
Forestry Commission scientists have confirmed that Phytophthora lateralis, a fungus-like pathogen that kills trees’ roots, has infected several trees in a shelter hedge on an industrial estate.
The disease is very infectious to Lawson Cypress and some other trees, but harmless to people, animals and most other plants. 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.
John Morgan, Head of Plant Health for the Forestry Commission 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.”
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 the either Forestry Commission’s Disease Diagnostic & Advisory Service.
Tel: 01420 23000
ddas.ah@forestry.gsi.gov.uk