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Washington State University
WSU Puyallup Ornamental Plant Pathology

Pests and Pathogens of Pacific Madrone


Pacific Madrone

Visit our About page to learn more about the importance and heritage of the Pacific Madrone. You can also learn more about the Pacific madrone research projects led by our program here.

Get Involved in Research

Join the Arbutus ARME if you are interested in contributing to research to better understand and find solutions for sustaining the health of Pacific madrone.


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.

Foliar Blight

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).

Root disease symptoms consist of wilting, yellowing foliage. Madrone stem cankers

Insect Pests

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.

Bark beetle frass on pacific madrone


Additional Information

Pest and Disease Notes

List of fungi associated with Pacific madrone

Madrone Health Concerns in the News

Technical Literature