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Laminated Root Rot

Learn about the management of Sunnyside's Laminated Root Rot Disease

A tree stump in Sunnyside Acres Urban Forest with evidence of of Phellinus sulphurascens.

Laminated root rot is a disease caused by a naturally occuring fungus called Phellinus weirri (or P. sulphurascens), found through many ecosystems in the Pacific northwest. It can cause the death or decline of evergreen species such as Douglas Fir, grand fir, Sitka spruce and Western Hemlock. In addition to impacting the health of the Forest, root rot also poses a risk to public safety by increasing the number of hazardous trees near trails, and exacerbating wildfire conditions by increasing fuel. Root rot was first identified as a forest health concern in 1999, and after extensive research and public consultation, root rot management activities began in the Forest in 2003.


The disease spreads by root contact at the rate of 50cm per year. Our management plan called for the felling of trees near afflicted areas to create a ten metre quarantine belt; the goal was to ensure that the roots of any diseased trees would not contact the roots of any remaining non-infected healthy trees.  These quarantined areas were then replanted with deciduous trees, such as alder, which can act as a natural "sanitizing" agent against the fungus. Unfortunately, prior to the establishment of the Urban Forest most alder trees were removed for firewood.

Laminated root rot continues to pose a significant threat to the health of Sunnyside Acres Urban Forest. We continue to work closely with City of Surrey staff to closely monitor the spread of root rot within the forest. Contact us if you would like to learn more.


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