Quercus agrifolia
One of the most common and widespread trees throughout coastal California. Native to California from Mendocino County south to Northern Mexico.
- Culture
- Concerns
- Management
Culture for Coast Live Oak
Performs best in rocky well-drained soils, often found in proximity to California bay laurel in moist areas and Valley oak in drier plains and hillsides. Drought tolerant, though may need some summer irrigation during very dry years. Most often multi-stemmed, younger trees are very dense and bushy in appearance while older trees (75+ years) develop thinner crowns with visible branch architecture.
Concerns about Coast Live Oak
Susceptible to sudden oak death (SOD), often impacted by Armillaria and other decay species which affect health and stability, more commonly when roots are disturbed or damaged. Planted vs. native ‘acorn’ grown trees should be discernible based on bark texture. Planted live oaks are more impacted by powdery mildew, pit scale insects, and gall wasps. Drought stressed trees are also attacked by western oak bark beetles, leading to ‘foamy canker’. Pit scale feeding sites are a common entry point for tip blight infection, and these problems often occur together. May be completely defoliated during CA oakworm outbreaks.
Management Practices for Coast Live Oak
Annual treatments for SOD are recommended, and treatments to prevent beetle infestation are recommended during moisture stress. Failure often occurs in large branches or whole tree due to basal decay. Pruning should focus on preventing or subordinating co-dominant stems early in development. Treat for oakworm during outbreaks which typically last 2-3 years.
Photos related to Coast Live Oak
Typical form and density of 20-50 year old coast live oak
‘Bleeding’ symptom of ‘sudden oak death’.
Powdery mildew on planted live oaks often leads to ‘witches broom’ symptoms.