Pests and Pathogens 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.

Phytophthora root rot

There are a few species of Phytophthora known to infect Pacific madrone. Phytophthora cinnamomi is a pathogen of concern for Pacific madrone populations in California. Another species, Phytophthora cactorum, which also infects fruit trees, is associated with root disease in Washington.

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 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.