Trees felled in fight against fatal disease in Clocaenog Forest

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7 MARCH 2011NEWS RELEASE No: 14473

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An outbreak of Phytophthora ramorum (P. ramorum) was recently found affecting a small number of Japanese larch trees in Clocaenog Forest, Denbigh.

Work is now underway to fell the infected trees to try to prevent the spread of this serious tree disease.

P. ramorum is a fungus-like pathogen that kills many of the trees that it infects. Infected Japanese larch trees produce high numbers of the spores that spread the disease, with the result that a lot of these trees can become infected very quickly.

Steve Cresswell from Forestry Commission Wales, which manages Clocaenog Forest on behalf of the Welsh Assembly Government, said, "Phytophthora ramorum is a fatal tree disease and, by felling infected trees here, we hope to limit the production of the spores that spread the infection and therefore minimise the impact of the outbreak."

Access to small sections of the forest will be restricted to the public while the felling operations are carried out.

P. ramorum is not harmful to humans or animals and, to avoid inadvertently spreading the pathogen, visitors to infected woodlands such as Clocaenog Forest are asked to observe some simple biosecurity precautions. These are explained on signs onsite and include keeping to paths, keeping dogs on leads, cleaning footwear and not taking any plant material away.

There is no evidence to suggest that the presence of P. ramorum in a tree makes its timber unusable and there is no risk of further spread from wood that has been processed.

The contractors harvesting the trees will follow biosecurity precautions when handling the logs and transporting them to saw mills that have been licensed to receive logs from infected forests.

P. ramorum was first discovered on Japanese larch trees in Great Britain in 2009 in South West England. It was then found on larch in public woodlands in South Wales in June 2010, where work to fell the infected trees is underway.

Forestry Commission Wales staff will continue to monitor trees for signs of infection but symptoms may not become evident until later this spring when larch trees – which are deciduous conifers – renew their needles.

Forestry Commission Wales has also asked for the support of private woodland owners in looking out for early signs of P. ramorum infection in their trees. To report suspected infection or to find out about the support available to them, woodland owners should contact Forestry Commission Wales’s Grants & Regulations Office on tel: 0300 068 0300 or email:

Further information about P. ramorum can be found on the Forestry Commission’s website at


  1. Phytophthora ramorum (P. ramorum) is a ‘quarantine’ organism under European Union law and its suspected presence must be notified to the relevant authorities (the Forestry Commission, Fera, the Welsh Assembly Government or the Scottish Government). It was first found in Britain on a viburnum plant in a nursery in 2002.
  2. P. ramorum can kill many of the plants that it infects, but symptoms vary according to the species. On Japanese larch (Larix kaempferi) trees, it causes shoot tips to wilt and needles to turn black and fall prematurely. Cankers that bleed resin can appear on the branches and upper trunk. Infected Japanese larch trees produce particularly high numbers of the spores that spread the disease – five times the level produced on rhododendron - meaning the disease can quickly affect a large number of trees and shrubs.
  3. P. ramorum was first discovered on Japanese larch trees in Great Britain in 2009 in South West England. It was then found on larch in South Wales in June 2010 in public woodlands in the Afan Valley, near Port Talbot, in the Garw Valley, near Bridgend and in the Vale of Glamorgan.
  4. Larch is a durable, versatile timber that tolerates changes between wet and dry conditions very well, and resists rotting when used in the ground. It is therefore in demand for outdoor uses such as fence posts, fence panels, exterior wall cladding, boats, sheds and furniture, as well as indoor uses such as flooring and chipboard. It is easily stained, worked and finished.
  5. About 14 per cent of Wales is covered by woodlands. Of this, 38% (126,000 hectares/311,000 acres) is owned by the Welsh Assembly Government. Forestry Commission Wales is the Welsh Assembly Government’s department of forestry and manages these woodlands on its behalf. Forestry Commission Wales provides advice on forestry policy to the Minister responsible for forestry. It provides grant aid to other woodland owners and regulates forestry by issuing felling licences. It is also part of Forestry Commission GB and contributes to the international forestry agenda. More information on the woodlands of Wales is available on


Mary Galliers, , tel: 0300 068 0057.