Phytophthora austrocedri (previously spelled austrocedrae) is an aggressive, fungus-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 austrocedri was first reported in the UK in 2011, and infected trees have now been found at sites in Scotland, and the north and south 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 austrocedri is a notifiable pathogen, and suspected cases in trade, such as in nurseries, must be reported to the plant health authorities.