Cotoneaster: Scab

categories: Cotoneaster Cotoneaster Diseases Ornamentals Shrubs

last review date: 2026-04-23 10:19

Biology

Symptoms of scab on cotoneaster are similar to those on apple. A fungal disease, scab causes leaves and fruit to develop dark or black blotchy spots.

Initially, the leaves show pale pinhead spots, which later darken to a velvety olive then black. The diseased leaves are often curled, puckered, or otherwise distorted.

Affected leaves may turn yellow prematurely. Moist conditions favor disease development.

Management Options

See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.

Non-chemical Management

Select non-chemical management options as your first choice!

• Rake and destroy fallen leaves and fruit to reduce reinfection chances.
• Avoid overhead irrigation or limit it to times when the foliage can dry quickly.
• Prune and space plantings to reduce humidity and improve air circulation.

Chemical Management

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

• Make a delayed dormant application.
• Repeat applications when foliage appears.
• 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

Examples of pesticides that are legal for home use in Washington State are listed below.
The list may not include all products registered for this use.

• Bonide Infuse Systemic Disease Control Lawn and Landscape
  Active ingredient: thiophanate methyl (EPA reg. 53883-183-4)