Larch tree disease found in Cumbria

Ramorum disease of larch trees has been found in Cumbria for the first time.

The disease, which kills larch trees very quickly and is a recent arrival in Britain, has been confirmed in two private woods in the Eskdale Valley in western Cumbria.

Larch trees produce large quantities of the spores that spread the disease, which can infect many species of trees and plants.

The only available disease control treatment is to fell the trees, preferably before the next spore release, which current knowledge indicates occurs in the autumn.

The outbreak is the second in North West England after one in southern Lancashire, and only the third outbreak in England outside the South West, where the disease has caused the premature felling of hundreds of thousands of larch trees.

[pullquote]Cumbria’s location and climate put it in a zone of moderate risk for the disease
Dr John Morgan  – Forestry Commission[/pullquote]

There have been findings of ramorum disease on other plants, such as rhododendron, near the affected woods.

Investigations are continuing into other suspected sites identified by aerial surveys in northern England, and the Forestry Commission believes there is a possibility that more outbreaks will be found.

Dr John Morgan, Head of the Forestry Commission’s Plant Health Service, said: “It’s disappointing to find ramorum disease on larch trees in Cumbria, but it’s not altogether surprising, given that there have been other infected plants nearby and that Cumbria’s location and climate put it in a zone of moderate risk for the disease.

“Overall, the number and area of outbreaks on larch that we are finding this year are down on the previous two years, and most are close to or contiguous with previously infected sites. However, these outbreaks in new regions demonstrate that the threat posed by this disease is still serious.

“We are therefore continuing to urge everyone who manages, works in or visits trees and woodland to keep a close watch for signs of the disease, not only in larch trees, but also in other susceptible plants, particularly rhododendron and bilberry. Anyone who suspects they have seen its symptoms should report it to us without delay.”

Ramorum disease

Ramorum disease is caused by Phytophthora ramorum (P. ramorum), a fungus-like pathogen that is particularly serious in Japanese larch trees and rhododendron, both of which produce large numbers of infective spores.

P. ramorum is not harmful to humans or animals.

The outbreak was first suspected during aerial surveys to look for signs of the disease by the Forestry Commission, in conjunction with the Food & Environment Research Agency (Fera). These are continuing over large parts of Britain.

Experts follow up with ground inspections and laboratory analysis of samples taken from trees showing possible symptoms of the disease.

Other larch woodland in surrounding areas is inspected from the ground to check whether the disease is more widely present.

Local woodland owners are being informed and given information about the disease and the measures for containing it.

P. ramorum is a ‘quarantine’ organism, and its presence on trees or woodland plants must be notified to the Forestry Commission, Fera or the Welsh or Scottish Government, which must take action to contain or eradicate it.

Suspected cases of ramorum disease in larch trees can be reported to:
Scotland – ddas.nrs@forestry.gsi.gov.uk; tel. 0131 445 2176;
England – plant_health_england@forestry.gsi.gov.uk; tel. 0117 372 1070;
Wales – bww.ts@forestry.gsi.gov.uk; tel. 0300 068 0300.

Further information

Symptoms and Diagnosis – DARD(NI) (.pdf)- http://www.dardni.gov.uk/p-ramorum-disease.pdf

Detailed information about P. ramorum, including a map of known outbreaks and a symptom recognition guide, is available from the Forestry Commission’s website at www.forestry.gov.uk/pramorum

Exotic Pest Alert  (.pdf) – http://www.forestresearch.gov.uk/pdf/epaversion3.pdf/$FILE/epaversion3.pdf

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