What is 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, more outbreaks have been found in Cornwall, Devon, Cumbria, Wales and Scotland.

Visit the UK Government website for more information on findings in England.

Visit the Welsh Government website for more information on findings in Wales.



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

Read the symptom guide, which illustrates some of the symptomatic trees from which Phytophthora pluvialis has been detected in the UK.

Reporting 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.

The Plant Health (Phytophthora pluvialis) Demarcated Area Notices

A risk assessment has been carried out by the UK Plant Health Risk Group, which has concluded that Phytophthora pluvialis meets the criteria to be classified as a GB quarantine pest for regulatory purposes.

To protect the country against this disease, under power conferred by The Plant Health (Official Controls and Miscellaneous Provisions) (Scotland) Regulations 2019, demarcated areas around confirmed outbreak sites have introduced movement restrictions on materials that carry a risk of spreading the disease using ‘Scotland Demarcated Areas’ Notices.

As of 24 January 2023, there will be three demarcated areas in place in Scotland:

These notices prohibit the movement of any plants for planting of the genus Tsuga, Pseudotsuga, Pinus and Notholithocarpus, that has originated within the demarcated area.

The demarcated area boundaries can also be viewed on our interactive map.

Provision is made within the notices to enable plant health inspectors to authorise movements of material from the demarcated area where this can be achieved without risking the spread of Phytophthora pluvialis.

How to request an authorisation

Requests for authorisation to move any plants for planting of the relevant susceptible species that have originated within the demarcated areas must be made to the Scottish Government Horticulture and Marketing Unit (HMU) by emailing This email address is being protected from spambots. You need JavaScript enabled to view it..

Relevant links

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