Canker Diseases can easily wipe out a variety of trees. Canker disease is a fungus that usually attacks wounded branches or trunks on trees and shrubs. I lost all of of my landscape Populus tremuloides – Aspen trees planted to Canker disease and so did all of the other home owners in the neighborhood. All of the hybrid Cottonwood trees all died to. The native Cottonwoods did not die, none of them. It seems Canker disease can strike numerous species of trees both Deciduous and Conifers. Here are some great resources to learn about this disease. Some articles suggest that there is nothing that can be done except try to cut the disease section of the plant, but yet others have a couple solutions. Best to read them all and then decide what to do.

Canker diseases by The Morten Arboretum

Cankers – Trees and Shrubs by Home and Garden Information Center

Cankers in Trees  by Backyardfarmer

Cankers on Trees: Various by Cornell University

Cytospora Canker – 2.937 by Colorado State University Extension

How to Beat Bacterial Canker on Cherry Trees by Orchard People