Phytophthora kernoviae (also known as P. kernovii) - background and diary of main events
In the course of surveys in 2003 for P. ramorum another species
of Phytophthora, now named as Phytophthora kernoviae,
was found in Cornwall causing similar damage to beech trees and rhododendrons.
This pathogen is taxonomically a distant cousin of P. ramorum.
It appears to behave in a similar fashion, sporulating on rhododendrons
and causing lethal stem cankers on trees. However, there is some evidence
that it may kill rhododendron more rapidly under UK conditions than P.
ramorum.
As P. kernoviae is a recently described species our understanding
and knowledge about its development, spread and survival is still limited.
Unlike P. ramorum it seems to have spread mostly by natural dispersal
through woodland (spores may be carried locally by rain splash, wind-driven
rain, irrigation or groundwater) rather than by movement on nursery stock.
It has not been reported from any other country, although expert speculation
is that it, too may have been introduced from the areas from which rhododendrons
have been collected by plant hunters. Outside Cornwall, where around 40
beech trees and two oak trees have been found affected, the only findings
have been on rhododendrons at a nursery in Cheshire (from which it has
now been eradicated) and three parks on the outskirts of Swansea.
A small scale exercise is now being undertaken, within existing Defra
and Forestry Commission financial provisions for 2005/6 and 2006/7, to
clear rhododendrons from those infected woods which present a particularly
high risk of spread
Diary of events
October 2003
New, unknown Phytophthora isolated from rhododendron and beech at two separate sites in Cornwall.
December 2003
CSL begins testing all PHSI samples for the new Phytophthora as well as for Phytophthora ramorum.
March 2004
Working name of Phytophthora taxon C (PtC) used for organism.
June 2004
First finding on Magnolia.
July 2004
P. kernoviae found on rhododendron at three sites in South Wales.
First findings on Gevuina avellana (Chilean hazelnut), Liriodendron tulipifera (tulip tree) and Michelia sp.
August 2004
Two woods with very high levels of infection in rhododendron understorey and several infected beech trees found in Cornwall.
First finding on Quercus ilex.
September 2004
First finding on Pieris.
First finding on a nursery.
October 2004
Phytophthora kernovii proposed as the name of the organism (now known as P. kernoviae).
November 2004
P.kernoviae found on two English Oak trees (Quercus robur).
Cornwall meeting on Phytophthora ramorum and meeting on Phytophthora kernoviae.
December 2004
The Plant Health (Phytophthora kernovii Management Zone) (England) Order 2004 gave Defra and Forestry Commission specific powers of action within a defined region of Cornwall where Phytophthora kernoviae was first identified. It aims to provide coherence of policy and action for the many landowners and members of the public affected by the disease and measures for its containment and eradication.
May 2005
Phytophthora kernoviae information sheet published.
February 2008
Phytophthora kernoviae found on Vaccinium on heathland.
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Page last modified:
14 July 2008
Page published: 22 Nov 2004