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Phytophthora austrocedri

Credit: Sarah Green - Forest Research

Credit: Ana Pérez Sierra - Forest Research

Credit: Forest Research

Credit: Forest Research

Pest or disease?
Disease

Causal agent:
Phytophthora austrocedri (fungus-like pathogen)

Host species:
Juniper and cypress trees 

Present in the UK?
Yes in England and Scotland

Tree Alert required?
Not by members of the public (trade and Observatree volunteer reports only)

Phytophthora diseases are caused by a genus of fungus-like pathogens called water moulds.

Phytophthora austrocedri is an aggressive pathogen of juniper and cypress trees, causing dieback and often fatality. Its origin is unknown. The disease was first confirmed in the UK in 2011 by Forest Research, who had been studying dieback in juniper trees. It has been found in England and Scotland only.

This disease is a particular problem for juniper, one of only three native conifer species in the UK. We only have a small number of juniper woodlands remaining, many of which are protected. The disease has been found in the second largest population of juniper at the Upper Teesdale National Nature Reserve. The pathogen primarily attacks the trees roots but can move further up. Symptoms include discolouration of foliage, dieback and lesions. Lesions are not visible unless the bark is removed. For more information on Phytophthora austrocedri please see the resources below.