Madrone: Leaf blight

Biology

Madrone trees suffer from numerous fungal leaf diseases. One such problem, madrone leaf blight, appears to be caused by a pathogen that damages leaves after periods of cold weather in winter or early spring. Affected leaves develop brown spots which coalesce and form large blotches. The damage is worse where water collects (on the tips and edges of leaves and in the lower part of the canopy). Heavily-infected leaves may turn completely brown, sometimes throughout the entire canopy. Damaged leaves usually remain on the branches for several months, finally dropping off at the end of the following summer. New leaves emerging in the spring typically do not show symptoms of leaf blight. Young or stressed trees may be more severely affected than mature, healthy trees. Little is currently known about the long-term effects of this blight, though repeated loss of leaves will likely affect plant vigor and survival. Leaf blight on madrone should not be confused with other fungal leaf spot problems, which typically cause only minor damage. See also Madrone: Leaf spot.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

• Until more is known about fungal leaf blight on madrone, good sanitation practices should be used when practical. Clean up and dispose of fallen blighted leaves around valuable landscape trees.
• Avoid stressing madrones with poor planting location or improper culture. They prefer native soils with excellent drainage, grow best in full or partial sun, and can tolerate poor soils.
• Good air circulation is important since fungal diseases are more severe in crowded, humid conditions.
• Do not irrigate established trees, as they are adapted to summer drought.

Chemical Management

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

• None recommended