Expansion of Sooty-Bark and Ceratocystis Cankers on Aspen. T. E. Hinds, Plant Pathologist, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO 80526. M. G. Ryan, Biometrician, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO 80526. Plant Dis. 69:842-844. Accepted for publication 19 May 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1985. DOI: 10.1094/PD-69-842.

Expansion of sooty-bark cankers, caused by Encoelia pruinosa, was measured on 143 aspen to predict years to tree mortality. The mean vertical expansion of 87 cankers was 44.9 ± 3.7 cm/yr. Cankers expanded circumferentially at a mean rate of 16.3 ± 0.7 cm/yr. Tree longevity can be predicted by dividing the circumference of the trunk not yet invaded by the canker by the horizontal expansion rate of the canker and adding 1 yr. Ceratocystis fimbriata seldom girdles a tree. The mean horizontal and vertical growth rates for 26 Ceratocystis cankers examined were 1.3 ± 0.2 and 2.8 ± 0.4 cm/yr.

Keyword(s): Cenagium singulare, Populus tremuloides.