Sirococcus tsugae

Sirococcus blight is a fungal disease of cedar and hemlock, including species like Atlas cedar, Himalayan cedar, Cedar of Lebanon, and Western hemlock. Sirococcus tsugae is the causal fungus for this disease and can cause significant damage, leading to the death of shoots and branches, and in severe cases, the entire tree. 

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. It is thought that the disease spreads through spores that can be transported by wind, rain, and contaminated tools or clothing. 

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, see the resources below.