The recent discovery and recognition of the organism P. kernoviae means there are many uncertainties about this pathogen. These include:
- Its mode of arrival in the UK
- Its geographic origin
- Its known distribution in the UK and elsewhere
- The level of environmental threat that it may pose to UK trees.
Mode of arrival and geographic origin
P. kernoviae is yet another invasive Phytophthora found to be causing damage and mortality to trees in the UK in the past decade. Others include the hybrid alder Phytophthora, P. alni, and the ‘sudden oak death’ pathogen P. ramorum. Another Phytophthora believed to be a recent invasive on trees in the UK is P. quercina, associated with the current episode of oak decline occuring in Europe. All of these Phytophthoras were unknown to science until recently and may have been introduced via international plant trade.
The geographical origins of P. kernoviae remain unclear. It is a pathogen which grows best at around 18 0C with an upper limit of 26 0C which suggests it is adapted to a temperate climate. This could indicate a possible origin in the temperate forests of the eastern Himalaya, China or Taiwan. Another possible origin because of its association with the proteaceous Chilean hazelnut (Gevuina avellana) is Patagonia.
Level of threat
A Pest Risk Analysis (PDF-168K) which reviews all available information about P. kernoviae has been drafted to help inform a review of the current policy for this pathogen in the UK.
