Septoria canker and leaf blight

Sphaerulina musiva

Septoria canker and leaf blight has recently become established in British Columbia. It was imported on hybrid poplar cuttings from eastern North America. 

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The main distinguishing feature of the septoria canker and leaf blight is its ability to induce two types of symptoms:

  • Leaf spot
  • Perennial cankers of stems and branches

The number and size of leaf spots varies with the hybrid. The spots are angular or irregular in shape. 

Host tree species

Canker formation in British Columbia is associated with hybrid poplar species.

Disease cycle

Canker development begins with tissue discolouration. Then, a depressed area of necrotic tissue forms, eventually leading to stem deformation. In more severe cases cankers can lead to stem breakage.


It's possible to reduce the magnitude and spread of this disease by removing and destroying the leaves of infected trees that drop to the ground in the fall.


The spots can cause a reduction in the tree’s photosynthetic activity and occasionally lead to premature defoliation.

The disease is limited to areas where hybrid poplar is grown in the Fraser Valley and some locations in the Okanagan Valley.