Phytophthora pluvialis

Phytophthora pluvialis, is a fungus-like pathogen known to affect a variety of trees including western hemlock, tanoak, pine (Pinus radiata, Pinus patula and Pinus strobus) and Douglas fir. It 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.

Phytophthora pluvialis was discovered in a woodland in Cornwall in September 2021, where it was found to be affecting mature western hemlock and Douglas fir trees. Following extensive surveillance, further outbreaks have been found in Cornwall, Devon, Cumbria, Surrey, Shropshire and at multiple sites in Scotland and Wales.

For further information on the Scotland findings and management approach please visit the Scottish Forestry website. For further information on the findings in Wales please visit the Welsh Government website.

Symptoms

Phytophthora pluvialis is known to cause needle cast, shoot dieback, and lesions on the stem, branches, and roots.

Read the symptom guide ( , 3.93 MB, 9 pages)which illustrates some of the symptomatic trees from which Phytophthora pluvialis has been detected in the UK.

Report sightings

Please remain vigilant for signs of Phytophthora pluvialis. If you think you have spotted signs of this disease anywhere in Great Britain then please tell us using TreeAlert.

Report suspected sightings in Northern Ireland using TreeCheck, the all-Ireland tree pest reporting tool.

Management

Where Phytophthora pluvialis is identified, landowners should follow good silvicultural practice and remove symptomatic trees as part of normal felling operations.

Biosecurity measures should be followed to reduce the risk of spreading tree pests and diseases. Vehicles, equipment and footwear should be cleaned before leaving the woodland. Read how biosecurity can prevent the introduction and spread of tree pests and diseases.

Regulation

Phytopthora pluvialis is not regulated as a quarantine pest for Great Britain.

A Rapid Pest Risk Analysis was produced in 2022 and updated in 2026 by the UK Plant Health Risk Group. The updated Rapid Pest Risk Analysis concludes that Phytophthora pluvialis does not meet the criteria to be a quarantine pest for Great Britain, and therefore statutory action should not be taken on findings.

Plant health (Phytophthora pluvialis) demarcated area notices

Effective from Wednesday 4 March 2026, the following notices introduced by the Forestry Commission under powers conferred by The Official Controls (Plant Health and Genetically Modified Organisms) (England) Regulations 2019 have been revoked:

• Cornwall and Devon - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 15) Notice made on 17 January 2023
• Cumbria - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 16) Notice made on 17 January 2023
• Herefordshire - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 17) Notice made on 17 January 2023
• Surrey - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 18) Notice made on 17 January 2023
• Gloucestershire - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 19) Notice made on 17 January 2023
• Shropshire - The Plant Health (Phytophthora pluvialis) (Demarcated Area No. 20) Notice made on 17 January 2023

There are no movement restrictions in place.