Plant Disease Management Handbook

See:

Poplar (Populus spp.) - Canker

See:

Poplar (Populus spp.) - Marssonina Leaf Spot

Image related to Aspen (Populus tremuloides)-Marssonina Leaf Spot

Numerous spots of different sizes.

Maryna Serdani, 2011.

Spores of Marssonina sp. on aspen.

Melodie Putnam, 1993.

See:

Poplar (Populus spp.) - Leaf Rust

Note Melampsora medusae (formerly M. albertensis) affects aspen.

See:

Poplar (Populus spp.) - Leaf and Shoot Blight

Note Venturia macularis (formerly V. tremulae) is found on aspen (P. tremuloides).

Many leaves with necrotic areas due to Venturia infection.

Jay W. Pscheidt.

Shoot blight due to Pseudomonas syringae on aspen.

Larry Moore, 1982.

Cause The fungus Ciborinia whetzelii (formerly C. bifrons) incites this fairly common foliage disease. The fungus overwinters as sclerotia after falling from leaves. An apothecium emerges in the spring to shed spores that blow onto healthy foliage. Infection occurs during wet spring weather as new leaves are expanding. Brown foliage develops about a month later. Incidence is greatest in dense stands in the lower canopy of tall trees.

See:

Poplar (Populus spp.) - Canker

Whole (street) tree has died due to Cytospora canker.

Jay W. Pscheidt, 2019.

Spores can can be seen as cirri, oozing tendrils, coming from pimple-like fruiting bodies.

Jay W. Pscheidt, 2019.

Image related to Aspen (Populus tremuloides)-Cytospora Canker

The bark has been cut away showing the transition zone between healthy tissue on the left and diseased tissue on the right.

Maryna Serdani, 2011.

Young twigs develop brownish, sunken areas in the bark.

OSU Plant Clinic Image, 2013.

When put in a moist chamber the fungal fruiting bodies exude spores that results in the curly threads seen on this branch.

OSU Extension Plant Pathology Slide Set, 1988.

See:

Poplar (Populus spp.) - Canker

See:

Poplar (Populus spp.) - Canker

Elliptical canker with blackened bark indicates infection over several years. (Tree observed on Pikes Peak Colorado.)

Jay W. Pscheidt, 2023.

Wounds can be an entry point for canker fungi.

Jay W. Pscheidt, 2023.

Cause The fungus Phellinus tremulae incites a common heartrot of aspen, which can be found in just about every PNW grove. It is critically important for wildlife tree-cavity formation. Studies in drier forests of the PNW indicate that aspen groves are hotspots for wildlife habitat, with a major "cavity nest web" that develops, started by primary excavating woodpeckers, and then including swallows, nuthatches, bats, and other mammals, etc.

Image related to Aspen (Populus tremuloides)-Aspen Trunk Rot

Conks are triangular shaped and indicate extensive decay.

Dave Shaw.

See:

Oak (Quercus spp.) - Armillaria Root Rot

Note In western North America, Armillaria species are common on dead aspen, but less commonly associated with disease of living trees than in eastern North America.