Rare killer tree disease discovered

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A FATAL new tree disease has been uncovered in woodland near Blubberhouses.

The discovery is just the second outbreak in England since the disease was identified last year.

The Forestry Commission and Yorkshire Water are now working to try to control the outbreak, which has affected more than 400 Lawson cypress trees on land owned by Yorkshire Water, the British Canoe Union and a private owner.

Geoff Lomas, recreation and catchment manager for Yorkshire Water, said, “This is a rare but fatal disease, and as a responsible landowner we’re doing everything we possibly can. We are taking expert advice from the Forestry Commission and working with our neighbours to contain the disease and stop it from spreading.

“The very fact that this disease has been uncovered at two sites hundreds of miles apart highlights its potential to spread, and there’s growing concern that it’s only a matter of time before it is discovered elsewhere, with potentially serious consequences for all Lawson cypress in the UK.”

The disease, caused by the fungus-like organism Phytophthora lateralis (P lateralis), works by attacking the tree roots and starving the plant of vital nutrients, with spores being spread either through water or through infected soil being carried on footwear, vehicle wheels, pruning equipment and other tools.

Its serious effects on Lawson’s cypress have already been well-documented elsewhere. The species is important in its native range in the coniferous forests of south-western Oregon and northern California, but it has been drastically reduced or eliminated from large areas by P lateralis.

The trees in Blubberhouses are being felled to try to contain the outbreak and biosecurity measures are in place for people working at the site. Visitors are being asked to thoroughly wash and dry their footwear before entering other sites with Lawson cypress, including their own gardens.

The felled trees will be chipped on site and the chips mixed into the soil to ensure they cannot be moved elsewhere.

P lateralis was previously thought to be largely confined to Canada and the United States. But recent cases found in Scotland, Northern Ireland, France and the Netherlands have prompted growing concern that wider inspections will reveal further cases.

The disease could have serious consequences for the ornamental plant industry if it became established in Britain because Lawson cypress is one of the most important conifer species in the ornamental plant trade.

Dr John Morgan, head of the Forestry Commission’s plant health service, said: “P lateralis is one of several destructive plant pathogens that have entered the UK in recent years, and many of these have been associated with the growth in the international trade in live plants.

“We and our colleagues in the Food and Environment Research Agency (Fera) need everyone involved with trees and forest plants to be vigilant for signs of these diseases, and to take ‘biosecurity’ precautions where advised to help us contain them and minimise their impacts.”

Chris Hawkesworth of the British Canoe Union added: “We’ve been using the Washburn River at Blubberhouses since 1967 in co-operation with Yorkshire Water.

“We wish to see tree diseases eradicated as quickly as possible in the area and are happy to co-operate with all concerned to ensure that this happens.”

For more information about P lateralis, including a guide to recognising the symptoms, visit www.forestry.gov.uk/plateralis.