Pest or disease?

Causal agent:
Phytophthora lateralis (fungus-like pathogen)

Host species:
Mainly Lawson cypress 

Present in the UK?

Tree Alert required?

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

Phytophthora lateralis is a pathogen that mainly affects Lawson cypress trees. It can also affect red-cedar, Sawara cypress, Pacific yew and juniper. This phytophthora is thought to be from Asia, it was first found in the UK in 2010 but how it got here is unknown. It is possible it arrived on imported plants. It has been found in all four countries in the UK but tends to be found more in Scotland and Northern Ireland.

The pathogen primarily attacks the trees roots but can move further up the tree. Symptoms include discolouration of foliage, dieback and lesions. The lesions are not visible unless the bark is removed. For more information on Phytophthora lateralis please see the resources below.