Pest or disease?

Causal agent:
Sirococcus tsugaeĀ (fungus)

Host species:
Cedar and hemlock trees

Present in the UK?

Tree Alert required?

Sirococcus tsugae, often called Sirococcus blight, is a fungal disease of cedar and hemlock.

Sirococcus tsugae is present in the UK, it was first recorded here in 2014 and is present in all four countries. Believed to originate in North America, how it arrived in the UK is unknown. Research into this fungal species is on-going as scientists aim to find out more about its lifecycle and distribution.

This disease causes needles to turn pink in summer, becoming brown later in the year. It also causes shoot death and needle loss. Cankers and resin bleeds may appear on the shoots and branches as the disease progresses. On closer inspection, black fruiting bodies of the fungus can be seen on the needles (these will look like small black dots). For more information on Sirococcus tsugae please see the resources below.