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Be vigilant for Phytophthora pluvialis

The Royal Forestry Society is urging woodland owners to check for signs of Phytophthora pluvialis after the fungus-like pathogen was found first in Cornwall and later in Cumbria.

By Wendy Necar · November 25, 2021

Picture: Crown Copyright

Phytophthora pluvialis is a fungus-like pathogen known to affect western hemlock, Douglas fir, tanoak and several pine species (in particular radiata pine). It is reported to cause needle cast (where needles turn brown and fall off), shoot dieback, and lesions on the stem, branches, and roots.

A routine plant health check in a woodland in Cornwall by the Forestry Commission had identified the pathogen. This was the first instance of Phytophthora pluvialis anywhere in Europe and it has since been confirmed in Cumbria.

The Forestry Commission introduced a demarcation area in Cornwall which was later extended to include Devon to avoid spread. A demarcation area comes into place in Cumbria on 26 November.

Forestry Commission, Forest Research and the Animal and Plant Health Agency are rapidly conducting further surveillance and diagnostic analysis to understand more about the pathogen and ensure that any required control measures are swiftly undertaken to stop its spread

Nicola Spence, the UK Chief Plant Health Officer, said: “We are taking swift and robust action against this finding of Phytophthora pluvialis, as part of our well-established biosecurity protocol used for tree pests and diseases.

“I urge all sectors to support efforts to tackle this pathogen by checking the health of western hemlock and Douglas-fir trees. Key symptoms to look for are lesions on the stem, branch or roots.”

For symptoms and guidance here.

Any sightings should be reported to the Forestry Commission via its Tree Alert online portal.

Phytophthora pluvialis, was originally reported in Oregon, USA in 2013 on tanoak and Douglas fir and was subsequently identified as the pathogen responsible for ’red needle cast’ of radiata pine in New Zealand.