Dogwood: Collar rot

categories: Dogwood Dogwood Diseases Ornamental trees Ornamentals

revision date: 2022-11-22 11:49

Knife pointing to area of shrub trunk with bark scraped away.
Phytophthora root rot infecting trunk
Photo by: R.S. Byther


Collar rot is caused by a soilborne fungus which usually infects the plant through wounds on the trunk. It can also infect roots. A canker develops on the trunk near the soil surface or on the roots just below ground. This later becomes sunken and the bark falls off. The tree dies if the trunk is girdled. The first symptom of infection is general poor health, followed by death of twigs and branches. The same fungus causes root or collar rots in several different plant species.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Prevent wounds on the tree trunk where the fungus can enter.
  • Remove and destroy infected trees, including large roots.
  • Do not replant in infected soils.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • None recommended