Phytophthora kernoviae - Frequently Asked Questions
What is Phytophthora kernoviae? Phytophthora kernoviae
Why is it called Phytophthora kernoviae?
This is the formal name given to the pathogen. It was initially given the working title Phytophthora Taxon C but the pathologist who discovered it, Professor Clive Brasier, Emeritus Mycologist at the Forestry Commission’s Research Agency, named it Phytophthora kernoviae after Kernow, the ancient name for Cornwall. It was also referred to as P. kernovii for a while.
In October 2003, during the course of surveys, Forestry Commission scientists isolated and characterised a Phytophthora from a large bleeding canker on a mature beech from the south-west of England that was different to Phytophthora ramorum. At the same time scientists from the Central Science Laboratory isolated an identical new organism from established rhododendrons, also from the south-west. Both were confirmed as being the same organism, now formally named as Phytophthora kernoviae. Since then, P. kernoviae has also been found at other south-west sites near to those already infected, at a site in Wales and in a nursery in the north-west of England. All samples submitted are now routinely analysed for Phytophthora ramorum and Phytophthora kernoviae.
Why are Defra and the Forestry Commission so concerned about the disease?
What action has the FC and DEFRA taken?
Information on the action taken can be viewed here.
Is Phytophthora kernoviae established in the UK?
P.kernoviae is not established widely in the UK, but occurs mainly in Cornwall and to a much lesser extent in South Wales.At present P. kernoviae does not appear to affect as many plant species as P. ramorum but there are indications that it is more virulent as it appears to be causing more serious damage to rhododendron. It has also been found causing potentially lethal infections on two English oaks and forty-five beech trees, as well as infecting other ornamental trees and shrubs. All this has increased our concern about the potential impact of this pathogen.Phytophthora ramorum and belongs to a different Phytophthora grouping. This is the first record of this pathogen anywhere in the world. is a fungal like organism which affects the aerial parts of its tree and shrub hosts. It was first found on rhododendron and a beech tree in Cornwall in 2003. It is genetically distinct from
What are its host plants?
The full host range of this organism is not known and its biology has yet to be fully investigated. However, so far the organism has been discovered mainly on beech (Fagus sylvatica) and on rhododendron (mainly Rhododendron ponticum). New hosts reported in 2004 were a single specimen of Chilean hazelnut (Gevuina avellana), tulip tree (Liriodendron tulipifera), at least four species of magnolia and Michelia doltsopa (similar in appearance to magnolia). Two English oak trees (Quercus robur) and Holm oak (Quercus ilex) have also been found with foliar infections. Three of these Phytophthora kernoviae hosts are known hosts of Phytophthora ramorum (F. sylvatica, Rhododendron spp., magnolia spp. and Q. ilex). In 2005 the pathogen was also found on Winters bark (Drimys winterii) and Pieris spp. The full host range is not known. Scientists at Forest Research and the Central Science Laboratory continue to investigate its biology.
Is research being undertaken into Phytophthora kernoviae?
This is one of our main priorities and our research programme has already been extended to help us understand how the organism spreads and the process of infection so that we can develop appropriate disease-management strategies. We have already designated one of the known infected sites in the south-west of England as an experimental site specifically for this purpose.
If you do not understand the disease, should plants be destroyed?
It is precisely because we know very little about the organism that, as a precautionary measure, we are taking action to destroy infected plants in the same way that we have for Phytophthora ramorum. However, it is possible that trees which become infected do not themselves become a source of infection, and this is being investigated at the research site in the south-west of England.
Are we trying to trace it in other countries?
Information about P kernoviae has been given to the EU Plant Health Committee and all Member States have now received provisional notification that there is a new Phytophthora affecting beech and rhododendron and we have supplied descriptions (morphological and molecular profiles) to enable scientists to identify it. Similar information has been made available to scientists world-wide. Some Member States are now looking for P. kernoviae as part of the obligatory surveys for P ramorum but so far it has not been recorded outside the UK. We will continue to be on the look out for this new Phytophthora species outside the locations where it has been found already.
What impact do we think it will have?
It is too early to say, but preliminary tests which show that Phytophthora kernoviae is capable of causing the same degree of damage to beech as we have previously found for P. ramorum. However, the impact that it could have will also depend on whether P kernoviae is widely distributed, or is confined only at the locations found so far in Cornwall and South Wales.
(Last updated: January 2006)
