Filbert: Bacterial blight
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Biology
Bacterial blight of filbert may attack buds, leaves, twigs, branches, and the trunk. Infected buds may be killed before leafing out. Leaves initially develop pale green, water-soaked spots, which later turn reddish-brown.
Current-season shoots show dark green, water-soaked spots on the bark. These later turn reddish-brown and can girdle the stem, causing dieback above the lesion. Leaves often remain attached to dead shoots. One- and two-year-old twigs are also attacked.
Infections may spread into main branches or trunks, where cankers may girdle and kill trees. The infected tissues may show a bacterial ooze in the spring, when most new infections occur. Bacterial blight is more severe on trees that have been damaged by frost, sunscald, or other problems.
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!
- Plant disease-free stock.
- Plant resistant varieties such as ‘Hall’s Giant’.
- Avoid highly susceptible varieties such as ‘Barcelona’.
- Provide proper culture. Healthy trees are more resistant to disease.
- Prune out and destroy infected tissues, making cuts 2′-3′ below infected branches. Disinfect pruning tools between cuts to avoid spreading bacteria to healthy tissues.
- Prevent injury to trees including sunscald and frost damage, if possible.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply in late August or early September.
- In seasons of heavy rainfall, apply again when 3⁄4 of the leaves have dropped.
- 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
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.