The pathogen Phytophthora pluvialis is a fungal-like water mould found in Scotland, infecting western hemlock (Tsuga heterophylla) and Douglas fir (Pseudotsuga menziesii).
How does Phytophthora pluvialis affect trees?
Symptoms of P. pluvialis infection include:
- needle cast
- shoot dieback
- lesions on the stem, branches and roots
More information about symptoms can be found in the Forest Research guide.
Phytophthora pluvialis: Symptoms on western hemlock and Douglas-fir (Forest Research website)
When was Phytophthora pluvialis discovered?
The pathogen was first described in 2013 from Oregon, USA, infecting tanoak (Notholithocarpus densiflorus).
One year later it was discovered to be the causal agent of ‘red needle cast' in radiata pine (Pinus radiata) in New Zealand.
Phytophthora pluvialis was discovered in Scotland in 2021 after extensive surveillance following the first UK detection in Cornwall.
First report of Phytophthora pluvialis in Europe causing resinous cankers on western hemlock (British Society for Plant Pathology website)
Report suspected sightings of Phytophthora pluvialis
Report suspicious symptoms on any tree in Scotland to TreeAlert using the general enquiry webform.
Use TreeAlert (Forest Research website)
The web form asks for:
- your contact details
- the location of the sighting
- clear photographs of the affected tree(s) in context and the symptoms
For more information on what to include in your report, visit the ‘TreeAlert - what to do page’.
What do you need to make your report (Forest Research website)
Once you submit your report, diagnosticians at Forest Research will review it. They may contact you to request additional details.
Any suspected findings of regulated pests or pathogens, such as Phytophthora pluvialis, will be sent to our Tree Health Officers for follow-up.
Restrictions apply in Scotland to manage Phytophthora pluvialis
A risk assessment conducted by the UK Plant Health Risk Group classed Phytophthora pluvialis as a GB quarantine pest.
As such:
- confirmed findings may be subject to Statutory Plant Health Notices
- movement restrictions apply in certain areas to plants for planting in particular genera
The UK Plant Health Risk Register entry for Phytophthora pluvialis has links to the rapid Pest Risk Analysis conducted in 2022
UK Risk Register Details for Phytophthora pluvialis (UK Plant Health Risk Register website)
