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.

On this page

• Description
• Host tree species
• Damage symptoms
• Management
• Identification images

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Description

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

Host tree species

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

Damage symptoms

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.

The number and size of leaf spots varies with the hybrid genotype. The spots are angular or irregular in shape and can cause a reduction in the tree’s photosynthetic activity and occasionally lead to premature defoliation.

Management

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. Research is being conducted to identify genotypes of hybrid poplar that are resistant to S. musiva in other jurisdictions.

Identification images

Multiple cankers above and below the branch scar on the stem of a hybrid poplar tree.

Poplar leaves affected by Septoria spp.