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Phytophthora pluvialis is a fungal-like pathogen which affects a variety of tree species.

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First published:
15 December 2021
Last updated:

Species affected by Phytophthora pluvialis include:

  • Western hemlock
  • Douglas fir
  • Tanoak, and
  • pine species (Pinus radiata, Pinus patula and Pinus strobus)

We have now found Phytophthora pluvialis in the Dyfi Forest, Gwynedd.
See the latest press release on Phytophthora pluvialis in Wales.

This follows several recent findings in England and Scotland.
For further information on England’s findings and response, please visit Phytophthora pluvialis - GOV.UK
For further information on Scotland’s finding and response, please visit Scottish Forestry.

We are currently exploring all options to reduce the spread of the disease. Natural Resources Wales (NRW) are carrying out surveys to understand the size of the outbreak. There are no restrictions in place at the moment. This will change as we understand more about the outbreak.

Signs and symptoms

Signs of Phytophthora pluvialis include:

  • needle cast – where needles turn brown and fall off
  • shoot dieback, and
  • lesions on the stem, branches and roots

Forest Research has prepared a symptom guide, which illustrates symptomatic trees.


If you suspect a tree of having this disease, report it via the TreeAlert online portal. Give as much information as you can, including the location and the species affected.

Wales Demarcated Zone Notice

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 Wales against this disease, under powers conferred by The Official Controls (Plant Health and Genetically Modified Organisms) (Wales) Regulations 2020, The Welsh Government will introduce demarcated zones around confirmed outbreak sites. Movement restrictions of material capable of spreading Phytophthora pluvialis have been introduced using Notices.

Demarcated Area 1 comes into force on 26 January 2022. The demarcated area applies to an area around Dyfi, Gwynedd and the boundaries are shown on the Demarcated Zone map. The Notice provides a description of the boundary.

The Notice prohibits the movement of any relevant susceptible material out of or within the demarcated area specified, unless authorised in writing by a Plant Health Inspector.

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