How to Manage Pests

Pests in Gardens and Landscapes

Canker diseases

A canker is a sunken area containing dead tissue on a stem or branch. It may not be clearly visible, or it may be a well-defined infection on woody parts that often becomes surrounded by layers of callus tissue. Cankers can cause foliage on infected branches to turn yellow or brown and wilt. Infected bark often discolors and may exude copious resin. On some canker diseases, small fungus fruiting bodies may appear on the lower surface of affected leaves and branches. Cankers can girdle and kill limbs or the entire plant. Many pathogens and abiotic factors cause cankers on various tree species.


Planting resistant cultivars, if available, is the primary strategy for managing canker diseases. Avoid planting species that are poorly adapted for local conditions. Provide plants with proper cultural care to keep them vigorous and to limit these diseases. Prune out dead leaves and dead and dying branches when they are first observed. Make the cuts in healthy wood beyond any apparent cankers. Once the main trunk is infected, pruning is of little value. Provide plants with moderate amounts of fertilizer to improve plant growth, except for pines, which shouldn't be fertilized at all when suffering from cankers. Avoid heavy fertilization, which may promote disease. You can find more information on pine pitch canker in the Pitch Canker Pest Note.

Cytospora canker
Cytospora canker

Pine pitch canker on Monterey pine
Pine pitch canker on Monterey pine

Statewide IPM Program, Agriculture and Natural Resources, University of California
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