Aspen Bibliography

Observations on the effects of stem cankers associated with Pezicula ocellata (Pers.) Seaver in young Trembling Aspen

Document Type

Article

Journal/Book Title/Conference

Canada Department of Forestry Bi-monthly Progress Report Forest Entomology and Pathology Branch

Volume

20

Issue

3

First Page

2

Last Page

3

Publication Date

1964

Abstract

In early summer, 1962, a high incidence of unusual stem cankers was observed in young trembling aspen trees in the Long Lac area of northwestern Ontario. The disease was characterized by single or, more often, multiple cankers on the stems. They were oval, and ranged from one-quarter to 2 in. in width depending upon the size of stems, and from one quarter to 3 in. in length. Frequently, repeated and vertically adjacent cankers merged to form elongated necrotic areas up to 4 ft. in length. The periphery of the diseased tissues was clearly defined by a continuous narrow ridge of yellowish brown bark. Most affected stems exhibited several single and multiple cankers. No relationship was noted between the positions of cankers on stems and the aspect. Discoloured tissue in the central parts of cankers was characteristically dark brown or black, whereas in the outer extremities it was yellow. The resultant colour contrast between cankers and adjacent pale-green healthy bark was a conspicuous character that simplified detection of infected trees, especially when they were wet with rain

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