Pests and Pathogens of Pacific Madrone
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Pacific madrone trees are incredible survivalists, but there are a few notable diseases that take their toll on madrone populations. Below we provide summaries of a few of the more common diseases associated with madrone in the Pacific Northwest.
Pacific madrone leaf blight is characterized by the presence of brown, desiccated leaves that first appear in the lower canopy. Learn more about the foliar blight here.
Phytophthora Root Rot
There are a few species Phytophthora known to infect Pacific madrone. Phytophthora cinnamomi is a pathogen of concern for Pacific madrone populations in California. Another species, Phytophthora cactorum, a species that also infects fruit trees, is associated with root disease in Washington. Read more about Phytophthora root rot of Pacific madrone here.
Stem and Branch Cankers
Multiple fungal species are known to cause cankers on stems and branches of Pacific madrone. Neofusicoccum arbuti is perhaps the most notable, causing large sunken cankers on the bole of the tree. More information about recognizing stem and branch cankers is available in this Presentation (PDF).
Insect pests are not typically regarded as major threats to Pacific madrone. However, please contact us if you observe any substantial insect damage.
Common insect pests of madrone include leaf miners and fall webworm. Occasionally damage from the western tent caterpillar is also observed.
Bark beetles are also occasionally observed in Pacific madrone trees, but they are often associated with injuries or other predisposing factors.
Please contact us if you observe any sign of substantial insect damage. More information about the insect pests associated with Pacific madrone is summarized in the OSU Extension Publication available below.
Pest and Disease Notes
- Forest Health Fact Sheet: Diseases and Insect Pests of Pacific Madrone, Max Bennett & David C. Shaw, Oregon State University Extension.
- Madrone (Arbutus menziesii) Canker, Pacific Northwest Pest Management Handbook, Oregon State University
List of fungi associated with Pacific madrone
- Diseases of Pacific madrone (Arbutus menziesii), U.S. National Fungus Collections Fungus-Host Database
Madrone Health Concerns in the News
- Are the Madrone’s dying? R. J. Rehwaldt, Shelton Mason County Jounral, May 26, 2011.
- Neofusicoccum arbuti: a hidden threat to Arbutus menziesii characterized by widespread latent infections and a broad host range, (2016), Canadian Journal of Plant Pathology, 38:1, 70-81,
- Fusicoccum arbuti sp. nov. causing cankers on Pacific madrone in western North America with notes on Fusicoccum dimidiatum, the correct name for Scytalidium dimidiatum and Nattrassia mangiferae, (2005), Mycologia, 97:3, 730-741,
- Role of fungal diseases in decline of Pacific madrone, Marianne Elliot, Robert L. Edmonds, and Scott Mayer (2002), Northwest Science Vol 76(4): 293-303.
- Arbutus menziesii Pursh – Pacific Madrone, Phillip M. McDonald and John C. Tappeiner (1990), Silvics of North America Volume 2, Hardwoods. Agriculture Handbook 654: 124-132.