This rapid PRA has been undertaken following a finding of the Oomycete pathogen Phytophthora pluvialis in Cornwall in September 2021. Subsequently, additional findings have been made elsewhere in England, also in Scotland and Wales on western hemlock and Douglas fir but not in Northern Ireland. Prior to the UK detections P. pluvialis was only known to be present in New Zealand and the Pacific Northwest (PNW) of the USA. In New Zealand it causes a disease known as red needle cast, primarily on radiata pine and Douglas fir, causing premature needle loss and loss of increment growth but trees recover. In the PNW it causes very minor damage on Douglas fir or tanoak and is considered part of the native forest mycota. This autumn 2022 version of the PRA has been updated as new information has become available.

November 2025 update (see appendix attached below): 

The rapid PRA for Phytophthora pluvialis was undertaken in 2022, following the first finding of this pathogen in the UK in 2021. The PRA highlighted a lot of uncertainties, and although the pathogen had already established outdoors in some areas of England, Scotland and Wales no final judgement was made as to whether it met the criteria for a Quarantine organism. Management options were put in place, but also a number of research projects were initiated to try and answer the key areas of uncertainty. This document provides updated information on this pathogen in relation to whether it meets the criteria for a Quarantine Pest for Great Britain (GB).