Phytophthora ramorum (Pr), Phytophthora kernoviae (Pk) and Phytophthora Lateralis
Introduction
These are serious fungus-like pathogens which attack trees, shrubs and heathland plants. They are closely related as they are both Phytophthoras, act in similar ways and are treated together for most purposes.
Pr is found in many countries in Europe and in the USA, where it has caused the phenomenon known as Sudden Oak Death. Pk is to date known only in the UK, Ireland and New Zealand.
In Great Britain, Pr was first identified in 2002 and Pk in 2003. Since then, there have been outbreaks at several hundred sites in England and Wales at nursery premises, in gardens and the wider environment. In Scotland, to 31 December 2012, there have been 36 separate findings of Pr at nurseries and retail outlets. In gardens and wider environment sites, there have been 41 distinct outbreaks (with Pr or Pk, or both pathogens) covering 70 premises which are spread across the country as shown on the map
In the UK the main host responsible for spreading both diseases is Rhododendron ponticum. This is a highly invasive non native plant, and there is concern about its potential to spread the diseases to native Scottish habitats. Heathland plants such as blaeberry and heather have been identified as being susceptible to Pr and Pk, as have trees such as oak and beech.
A Consultation on Future Management of Risks from Pr and Pk took place in July 2008 and a report on the analysis of responses is available.
The Scottish Government, with the Forestry Commission, has issued a report on the current status of Phytophthora ramorum and P. kernoviae in Scotland, with details of the programme of controls to be implemented from 2010 onwards. Details of the current situation in other parts of the UK are available from Forestry Commission and Fera websites.
Phytophthora lateralis has been detected in the UK on Lawson's cypress (C. lawsoniana), which is the primary host. Other potential hosts include the Pacific Yew (Taxus brevifolia) and White Cedar (Thuja occidentalis). The pathogen is not regulated by EU Plant Health legislation, but Member States can take national action to protect themselves. Measures designed to prevent accidental spread of P. Lateralis or P.ramorum from outbreak sites have been put in place.
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