Phytophthora austrocedrae is an aggressive, fungal-like pathogen that poses a serious threat to juniper trees in Britain. Juniper is an important native species and a significant proportion of the small area of juniper woodland in Britain is protected. Phytophthora austrocedrae was first reported in the UK in 2011 and infected trees have now been found at sites across Scotland and the north of England. The pathogen primarily attacks the roots of juniper trees, killing phloem and forming lesions which extend up into the lower stem. Eventually the tree will be killed by girdling of the main stem. Phytophthora austrocedrae is a notifiable disease and all suspected cases should be reported to the plant health authorities.