Viburnum: Bacterial blight (Leaf spot)

categories: Ornamentals Shrubs Viburnum Viburnum Diseases

revision date: 2022-12-04 12:00

Viburnum bacterial blight (leaf spot).
Viburnum bacterial blight (leaf spot)
Photo by: R.S. Byther

Biology

Bacterial blight of viburnum primarily affects leaves and occasionally stems. Spots on leaves first appear as brown, watersoaked areas which may be round, irregular, or angular in outline. Developing leaves may become deformed if heavily infected. Spots on stems may be more elongate and less noticeable than the leaf lesions and may also become sunken. Lesions on both stems and leaves may give off a bacterial ooze or exudate near the margins. Severe infections may also result in shoot dieback. Bacterial blight is favored by cool, moist conditions. The bacteria can infect through wounds and are easily spread by splashing water and pruning tools.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • Plant resistant viburnums such as Viburnum burkwoodii ‘Mohawk’, V. carlcephalum ‘Cayuga’, V. lantana ‘Mohican’, or V. rhytidophyllum ‘Alleghany’.
  • Plant in full sun.
  • Space plants and prune to provide good air circulation.
  • Remove and destroy infected leaves and shoots in dry weather. Sterilize pruning tools between cuts.
  • Rake and destroy fallen leaves.
  • Avoid wounding plants, especially during conditions favoring infection.

Chemical Management

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

  • Apply fungicides in September and again before fall rains.
  • An additional application may be made as new growth emerges in the spring.
  • 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.