Willow: Bacterial twig blight

categories: Ornamental trees Ornamentals Willow Willow Diseases

revision date: 2024-06-05 10:24

Willow bacterial twig blight.
Willow bacterial twig blight
Photo by: R.S. Byther


Bacterial twig blight of willow is caused by the same bacterium that causes bacterial blight of lilac and other woody ornamentals. The disease attacks twigs and branches, causing them to die back. Leaves on affected branches turn brown, wilt, and drop, sometimes resulting in severe defoliation. Young shoots are often girdled. Affected branches may show brown streaks in the wood when cut. The bacterium overwinters in the twig and branch cankers and reinfects new leaves in the spring.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • Prune and destroy affected twigs and branches (when practical).
  • Maintain proper plant nutrition. Healthy plants resist disease better.
  • Avoid overhead irrigation.
  • Space plants properly and prune to provide good air circulation.

Chemical Management

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

Monterey Liqui-Cop Copper Fungicidal Garden Spray can only be used on weeping willow. For best results, apply in fall after leaves drop. However, some labels may not allow this timing. Always follow label instructions. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.

Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.