What’s That Black Stuff?

2 minute read – 

That ‘black stuff’ on the aspen trees is a common fungal infection called Black Canker.  Once infected, a circular dead area, or canker, develops on the trunk. Old cankers can develop large folds of black, dead bark. The blackened bark gives black canker its name.

The cold never bothered me anyway! This is not due to cold weather and will not actually kill the tree. One of the oldest known cankers is over 78 years old (in a 103 year old tree)! Black Canker develops slowly. It normally doesn’t kill the tree directly. 


Instead, cankers allow wood decay to weaken the trunk making the tree easier to break. Luckily, the broken trunks provide habitat for cavity nesting birds like woodpeckers. Cankers are an essential part of healthy, diverse forests.

Lindsay Caskenette

Lindsay Caskenette

Manager of Visitor Services

Lindsay joined the Wildlife Preserve team March 2014. Originally from Ontario, she came to the Yukon in search of new adventures and new career challenges. Lindsay holds a degree in Environmental Studies with honours from Wilfrid Laurier University and brings with her a strong passion to share what nature, animals and the environment can teach us.


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