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NEWS RELEASE No: 134928 APRIL 2010

Forestry Commission and woodland owners join forces to contain ‘new’ tree disease

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Last August, the Forestry Commission discovered that the fungal-like disease, Phytophthora ramorum had moved from its previously known host plant, rhododendron to Japanese larch trees. [1]

Following this discovery of a change in the disease dynamics in the South West of England, the Forestry Commission conducted a rapid survey of the public woodlands it manages across the South West and more widely to evaluate any further spread of the disease. Private woodland owners and their representative bodies in the area have been kept informed of developments - with a number of owners reporting suspicious symptoms for investigation. [2]

As of last month, a total of five sites have been confirmed with infection and consequently had Plant Health notices served on them. Three of these are within woodland managed by the Forestry Commission and two in private ownership. To date, no infections on Japanese larch have been found outside the South West. [3]

When in needle, diseased Japanese larch is a source of very large quantities of infectious spores. Therefore, acting on the best available scientific advice, the Forestry Commission set itself the target of felling all confirmed infected sites ahead of spring bud-burst to minimise risk of further disease spread. [4] That target has been achieved on all three infected sites the Forestry Commission manages in the South West – with the same action being taken on the two sites in private ownership.

Paul Hill-Tout, Director of Forestry Commission England, who is visiting the South West today to inspect affected areas and thank private woodland managers for their prompt action said:

“The Forestry Commission’s overriding objectives are to seek to contain the disease and limit its impact on Britain’s trees, woods and forests.

Felling those confirmed infected trees before they came into bud was a critical deadline to achieve. I want to thank those private woodland owners who recognised the risks this disease could present to UK forestry if left unchecked and who acted selflessly and swiftly to support our efforts to contain it.

But we’re only in the early stages of understanding the change in the dynamics of this disease and the full extent of its spread  – ongoing vigilance and cooperation of private owners is vital in tackling this new threat to our trees.’

Chris Roberts, South West Regional Director of ConFor, the body representing private woodland owners, said:

"It is important that the private and public sector work together to minimise the impacts of this disease on UK forestry. There are hundreds of private woodland owners in the South West alone and I would urge them to report any suspicious symptoms in their trees – especially in Japanese larch.  Prompt action by individual owners will benefit the forestry and woodland sector overall.’

Alongside this action of precautionary felling, the Forestry Commission is extending its disease monitoring programme (using the latest remote sensing and air survey techniques), focusing scientific effort on increasing our understanding of the disease dynamics, and putting in place biosecurity measures on and around affected sites. [5]

Japanese larch is an important, widely planted commercial tree species – occupying about 8% of all woodland in Cornwall, Devon and Somerset.  About 76% of the Japanese larch is growing in privately owned woodlands, widely distributed throughout this region. [6]

Paul Hill-Tout, Director of Forestry Commission England can be contacted via the Press Office.  The Forestry Commission’s District Manager for the SW region, Chris Marrow is also available for comment.
Chris Roberts can be contacted via: Confederation of Forest Industries UK (Ltd) 0131 240 1410

Stuart Burgess, Senior Press Officer, Forestry Commission, tel 0117 372 1073, mobile 07785 748351, email

Chris Johnson, Press Officer, Forestry Commission, tel 01223 346034, mobile 07867580492, email

1.  Phytophthora ramorum had been found on a number of sites across Great Britain previously, but mostly infecting shrubs such as rhododendron and the heathland plant, bilberry. A small number of tree species had also been affected (notably beech), but only when growing in very close proximity to infected rhododendron.
In August 2009, the disease was found on a small sample of dead and dying Japanese larch (Larix kaempferi) in the South West.  This raised levels of concern, because some of the affected trees were not close to infected rhododendron. 

It may be that climatic conditions (warmer, wetter) in the South West favour this change in the dynamics of the disease.

Despite its popular name in America of “Sudden Oak Death”, our native oak species do not appear particularly susceptible to Phytophthora ramorum - although a small number of Sessile oak (Quercus petraea) growing in close association with infected Japanese larch, has been found to have been affected.

Single examples of other commercial conifer species, Western hemlock and Lawson’s cypress, have been found with infection, again when growing in association with Japanese larch.

To date, the disease has not been found on European larch.

2. The Forestry Commission’s initial survey carried out over the past three months covered FC woodlands throughout the western half of the country from the SW to the NW of England and eastwards to the New Forest, focussing on areas where Japanese larch was known to be growing - including but not always in association with rhododendron.

3. Confirmed infections are restricted to Cornwall, Devon and Somerset.  Affected sites managed by the Forestry Commission include Largin Wood in Cornwall, Plym Woods east of Plymouth and Canonteign Woods near Exeter.

4. Infected Japanese larch are the source of high quantities of disease-causing spores during the growing season- significantly higher than those produced by rhododendron. Direct tree-to-tree and air-borne infection are believed to be the key routes in this outbreak.

5. Biosecurity measures to minimise the risk of spread from felling operations include washing down vehicles, footwear etc. to remove mud and infected needles. 

The disease has been isolated on the bark of logs from infected trees, but it does not produce spores from the logs.  Therefore, research is also underway to assess the risks from transporting logs off site for processing.  Until that is complete, no timber will be moved off affected sites.

Access for walkers, horse riders and other forest users will be restricted while felling operations take place – as is routine practice for safety reasons around any site where felling is taking place.

Forest users will be advised by signs on site of additional measures appropriate to each site - e.g. staying on marked hard paths, keeping dogs on leads (to avoid picking up infected needles) and as per tree-felling operators, removing soil and mud from footwear before leaving sites.

NB - This is a disease affecting trees and shrubs, there is no risk to human or animal health.

6. Woodland owners or managers concerned about the health of their trees should in the first instance visit the Forestry Commission’s Plant Health website which is regularly updated and includes detailed descriptions and photographs of the disease.
Go to:  , then click on “Symptoms”

Owners suspecting their woodland is infected or showing any suspicious symptoms should contact: Forestry Commission South West England regional office, Mamhead Castle, Mamhead, Nr Exeter, Devon EX6 8HD. Tel: 01626 890666; fax 01626 891118; email:

At present, the Forestry Commission is primarily concerned about Japanese larch plantations in a forest and woodland environment rather than individual garden, parkland or amenity trees.
Anyone concerned about an individual garden, parkland or amenity tree should contact the Forest Research Tree Health Diagnostic Advisory Service on 01420 23000 or visit

Owners of parks and gardens can also find further information at: