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Urban tree disease found in England

forestry com

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.”

“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.

1. P. lateralis is thought to have originated in Asia before being introduced to North America, where it has caused the collapse of the Lawson cypress nursery industry in western states of the USA.

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 on; tel: 01420 23000; or by post to Disease Diagnostic & Advisory Service, Forest Research, Alice Holt Lodge, Farnham, Surrey GU10 4LH or the Fera Plant Health and Seeds Inspectorate Tel.: 01904 465625 Email: Web: 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.

Further information about P. lateralis, including frequently asked questions, is available from the pests and diseases section of the Forestry Commission website at and Fera has recently published a factsheet on P. lateralis.

Hygiene precautions can be found on the Forestry Commission website [PDF]

2. Lawson Cypress (Chamaecyparis lawsoniana) is not an important forestry tree (around 2,200ha in England) although it is highly valued ornamental tree. P. lateralis can also infect other Chamaecyparis species and Pacific yew (Taxus brevifolia), a close relative of Britain’s native yew (Taxus baccata).

3. We do not intend to release the specific site location while we tackle the finding and investigate its source.

4. The Tree Health & Plant Biosecurity Action Plan brings together all sectors concerned with the management of woods and forests. The text of the Action Plan for Tree Health and Plant Biosecurity is available from

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