Phytophthora are a large group of fungus-like pathogens which attack a range of trees, shrubs and heathland plants and have the potential to cause significant damage in gardens, woodlands and the wider environment.
Phytophthora ramorum (Pr) was identified in 2000 as the pathogen responsible for the sudden death of oak trees in California and Oregon and for dieback of rhododendron nursery stock in The Netherlands and Germany, both of which have been observed since the early 1990s. It has since been found in the nursery trade and the wider environment in Europe. In Scotland, there have been a few findings each year of Pr at nurseries and retail outlets, and in gardens and wider environment sites across the country.
Phytophthora kernoviae (Pk) was first discovered in Cornwall in 2003 during inspections for Pr and, to date, is only known in Britain, Ireland and New Zealand. The first finding of Pk in Scotland was in January 2008. So far there has been very little spread outwith Great Britain and, while we are aware that it can cause similar damage to certain species to that from Pr, it’s long term impact is unknown. There is no specific EU legislation dealing with the disease but in GB the same measures have been taken against it as are required for Pr.
Map of outbreak locations for Pr and Pk
Further information on the inspection and control of the above organisms is available in the recently published Strategy and Status Report.
Phytophthora lateralis (Pl) was first detected in Great Britain in 2010. It’s main host is Lawson's cypress (C. lawsoniana) and other named hosts include 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. In the UK, statutory action is taken against findings in commercially traded plants, but not in the wider environment, public parks/gardens and private gardens. In Scotland, the disease has been located here.
Phytophthora austrocedri (Pa) (previously spelled austrocedrae) was first reported in the UK in 2011 and infections have since been detected in Scotland and North England. It has also been detected on mature ornamental juniper at sites in Scotland. The impact of Pa is limited in the UK as a whole. Statutory action will be taken against findings on nursery plants for movement but not in the wider environment, other than in exceptional circumstances.