Phytophthora kernoviae is a new and damaging exotic pathogen of trees and shrubs which was first detected in Cornwall, UK in October 2003 affecting beech (Fagus sylvatica) and rhododendron understorey in woodlands. P. kernoviae is considered to be established in the UK with a limited distribution and is subject to official control. It is on the EPPO Alert List but is not currently listed as a quarantine pest by the EC.