Cedar: Seiridium canker

categories: Cedar Conifers Ornamentals

revision date: 2023-02-08 12:00

Hand in blue glove holding cedar bow.
Seiridium canker
Photo by: M. Harris


Seiridium cardinale and Phaeobotryon cupressi are fungal pathogens which cause yellowing or browning of the foliage. The result is flagging, the dieback of branch tips and entire branches of trees in a random distribution throughout the canopy. Cankers may be observed which are wounds or necrotic lesions often sunken beneath the surface of the stems or branches. Fungal spores can be spread by rain, irrigation water, insects, or pruning tools. The spores can enter through wounds or cracks in the bark, insect holes, or storm damage. Environmental factors such as drought or storm damage may cause stress on trees which make them vulnerable to these fungi. In the Pacific Northwest Incense cedar is particularly susceptible to this disease. Other possible hosts might include Leyland cypress, False cypress, Monterey cypress, Arborvitae, and Juniper.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • Give the plants appropriate care. This keeps trees vigorous and helps them to better resist disease.
  • Provide sufficient water especially during drought conditions. To retain moisture apply mulch a few inches away from the trunk.
  • To manage the disease, make pruning cuts well below the infected area during dry weather and especially before fall rains. Sterilize pruning tools between each cut to avoid spreading disease. Remove and destroy infected branches.
  • Plant disease resistant varieties such as western red cedar.

Chemical Management

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

  • None recommended.

Additional Images