Apple: Crown gall

Biology

Crown gall is caused by a soilborne bacterium. The bacteria infect through wounds on the crown and roots. Young galls are fleshy, white, enlarged masses on the roots or stems. Older galls are hardened and turn dark brown and woody or corky in appearance. They range in size from less than an inch to several inches across. The bacteria can be spread from infected to clean soil by water movement or equipment. Damage varies with location and size of galls. Small galls are essentially harmless. Large galls on the crown may weaken or girdle trees. The growths can also be an aesthetic concern. Burrknot, a physiological problem of apple trees, can be mistaken for crown gall.

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 disease-free materials.
• Remove and destroy declining trees with large crown galls. Also remove roots and surrounding soil where possible.
• Prune out galls when practical. Sterilize pruning tools between cuts to avoid spreading bacteria to healthy tissue.
• Avoid injuries to the bark, roots, and crown while planting.
• Do not replant susceptible species in infected soil.

Chemical Management

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

• None recommended.

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