This is the first time that conifer species have been found with stem lesions caused by Phytophthora ramorum. Many of the infected trees are not growing in close proximity to Rhododendron.
Scientists from the Forestry Commission's Forest Research agency have isolated Phytophthora ramorum on these sites and are investigating further. As a priority they are now carrying out more extensive tests and research to determine whether Phytophthora ramorum is the main cause of the outbreak. Apart from a number of Japanese larch and Western hemlock trees, some broad-leaf species (beech, birch and some oaks) growing in the same area are also infected.
Forestry Commission Plant Health Service head Roddie Burgess said: "This new find could represent a significant step change in the susceptibility of our trees to this disease, so we are very concerned about this development. With our partners in the Food & Environment Research Agency (FERA), as well as scientists in our Forest Research agency, we are working extremely hard to learn as much as we can, as quickly as we can, about what's happening. We can then consider what we need to do to manage the situation, building on the current programme of work to manage risks from this pathogen."
Burgess added: "It is important to stress at this time that much more research is needed to give us a full picture and allow us to assess what the potential implications are. Once we have done that we will share our findings with local woodland owners and managers."
Defra announced it would provide £25m to fund a five-year programme, which began on 1 April this year, for research, development and further disease control measures.
A Forestry Commission representative said: "We have so far identified four main areas: in east Cornwall, around Plymouth, in north-west Devon, and west Somerset, with further sites under investigation in mid-Devon. Infection by Phytophthora ramorum on Japanese larch has been found in a mix of privately owned and publicly managed forests. Infected sites managed by the Forestry Commission include Largin Wood in Cornwall, Plym Woods, east of Plymouth, and Canonteign Woods, near Exeter."
Local forest and woodland managers who wish to be kept informed should contact the Forestry Commission's south-west England regional office at Mamhead Castle, Mamhead, Nr Exeter, Devon EX6 8HD. Telephone 01626 890666, fax 01626 891118 or email email@example.com.
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