Ornamental Pear: Pseudomonas blossom blast and dieback

categories: Ornamental Pear Ornamental Pear Diseases Ornamental trees Ornamentals

revision date: 2022-11-27 04:00

Pseudomonas cankers on pear twigs.
Pseudomonas cankers on pear twigs
Photo by: R.S. Byther


Blossom blast and dieback is caused by a bacterial infection. The infection causes buds to turn a papery brown and die. Leaves may be spotted. Flower petals and stems may also be affected, and fruit cluster bases can turn brown or black. Occasionally, fruiting spurs may be killed. Cankers may develop in twigs and branches. Symptoms of this disease, especially on flowers, may closely resemble fire blight. However, blast infections seldom extend more than 1″-2″ into a spur. Bacterial ooze, which is common with fire blight, is not present with Pseudomonas blast. Fruiting pears and most Asian pear cultivars are also susceptible. Frost and cold injury promote infection, which is common in cold, wet springs. Warm, dry weather inhibits disease.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • Avoid wounding plants.
  • Prevent frost injury when possible. Plant hardy varieties in protected locations.
  • Provide proper culture to minimize amount of succulent shoot growth and to reduce injuries.
  • Prune out and destroy infected tissues as soon as they are noticed. Make cuts at least 6″ below infected areas and sterilize pruning tools between cuts.

Chemical Management

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

  • Apply before fall rains and again before spring growth starts.
  • Excessive amounts may cause russetting on fruit (if present).
  • 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.