First case of tree disease found in private woodland in Wales

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25 AUGUST 2010NEWS RELEASE No: 13966

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An outbreak of Phytophthora ramorum (P. ramorum) infection has been discovered for the first time in Wales on trees in a privately-owned woodland.

Staff from Forestry Commission Wales and Fera (the Food & Environment Research Agency) have visited the owner of the woodland in Denbighshire and a notice has been served to fell the infected Japanese larch trees. Only a small number of trees are infected, and the owner will use the timber on site.

P. ramorum is a fungus-like pathogen that kills many of the trees that it infects. It was first found on Japanese larch trees in Wales in June this year in public woodlands in the Afan Valley, near Port Talbot, in the Garw Valley, near Bridgend and in the Vale of Glamorgan.

The outbreak in South Wales was the first time P. ramorum has been encountered on larch elsewhere in Great Britain since it was first discovered on larch in South West England in 2009.

Richard Siddons, Head of Grants and Regulations for Forestry Commission Wales which manages the public woodlands on behalf of the Welsh Assembly Government, said, "Forestry Commission Wales is determined to minimise the impacts of this serious tree disease on woodlands, and the support of woodland owners in looking out for early signs of P. ramorum infection will play a key part in achieving that."

In July, the Forestry Commission announced a £600,000 support package for woodland owners in South West England and Wales to help tackle the outbreak of P. ramorum infection on larch trees. The package is part of Defra’s £25 million, five-year Phytophthora management programme.

Forestry Commission Wales is developing a complementary programme of support for private woodland owners who have P. ramorum confirmed on their land. Details of this support will be announced in September.

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

To find out more about the support fund or to report suspected P. ramorum infection in their trees, woodland owners should contact Forestry Commission Wales’s Grants & Regulations Office on tel: 0300 068 0300 or email:


  • 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.
  • 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.
  • P. ramorum has not been found infecting any European larch (Larix decidua) or hybrid larch (Larix x eurolepsis) trees, which are the other two species of larch grown in Britain, but these species are being kept under close surveillance.
  • P. ramorum can be spread on footwear, vehicle wheels, tools and machinery that have been used in infected forests, or by the movement of infected plants. It can also be spread in rain splash, mists and air currents.
  • P. ramorum has not been found on any trees in Scotland, and it is not harmful to humans or animals.
  • P. ramorum causes the disease known as "sudden oak death" in the USA, where it has killed millions of American native oak and tanoak trees. However, this name is a misnomer in Britain, where laboratory tests have shown that our two native species of oak, sessile and pedunculate oak, are much more resistant to P. ramorum than their American cousins. Fewer than five native oak trees have been confirmed with P. ramorum infection in Britain.
  • P. ramorum should not be confused with acute oak decline (AOD), which is a separate disease affecting oak trees in the Midlands and parts of Wales and South East England, and in which a newly discovered bacterium species appears to be involved.
  • 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. Complete figures are not available for Japanese larch numbers alone, but all three larch species together cover an estimated 134,000 hectares in Britain, or about 5 per cent of total woodland. Individual country figures are:
    • Wales – 23,000ha / 8 per cent;
    • England – 43,000ha / 4.3 per cent;
    • Scotland – 65,000 ha / 5.1 per cent.
    • (To convert hectares to acres, multiply by 2.47)
  • 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


For information about P. ramorum: