Sooty bark canker, Encoelia pruinosa

Fig. 372 Elongated black cankers of Encoelia pruinosa on mature trembling aspen.	Fig. 373 Grey, cup-shaped fruiting bodies of Encoelia pruinosa..

Distribution:  Throughout the range of its hosts.

TREE SPECIES ATTACKED:  Trembling aspen is the major host. Black cottonwood and balsam poplar are occasionally attacked. 

WHAT TO LOOK FOR: Large black cankers on the stem up to several metres long. Small, grey, cup-shaped fruiting bodies in the cankered areas of dead trees. Dead bark that easily crumbles and resembles soot. 

SIGNS & SYMPTOMS: The fungus commonly attacks older, injured trees. Upon entering a wound, the fungus grows into the inner bark and cambium. A canker begins as a sunken oval with blackened inner bark. Its development is so rapid the tree cannot form defensive callus tissue. Cankers can expand in length 1 m in one year, reaching a final length of 3 to 4 m. The outer bark will later slough off to expose the sooty, black, inner bark. After tree death, small (1 to 3 mm) grey, cup-shaped fruiting bodies are produced in blackened areas where bark has fallen off. The dead bark resembles soot as it crumbles in the hand. The disease is found primarily in trembling aspen stands that are mature or over 60 years old.

DAMAGE: In northern and interior BC, Encoelia pruinosa is the most damaging primary canker pathogen of aspen. 

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BC Ministry of Forests
Forest Practices Branch
P.O. Box 9513 Stn. Prov. Gov.
Victoria, BC
V8W 9C2

Section phone: (250) 387-8739
Section fax: (250) 387-2136

Last updated March 04, 2002