Crown Gall

Symptoms by part

Causes

• The Agrobacterium tumefaciens bacteria entering the plant through fresh wounds.
• Soil that is already contaminated with the bacteria from previous infected plants.
• Root damage caused by transplanting, cultivation, or pests like nematodes.

Could be confused with

• Callus tissue · Callus tissue forms uniformly around a pruning cut or graft union, whereas galls are irregular, bumpy, and grow randomly.
• Burl · Burls are natural, slow growing woody growths that do not have the spongy, soft texture of young galls.

Treatment

1. Prune away small, localized galls on branches using sterile tools, cutting well into healthy tissue.
2. Disinfect all pruning tools with a strong alcohol solution between every single cut to prevent spreading the bacteria.
3. Remove and destroy the entire plant if the gall is located on the main trunk or crown, as the plant cannot recover from this point.

Without chemicals

• Sterilize all garden tools with a high percentage alcohol solution after working on any suspected plant.
• Remove and discard infected plants and their surrounding soil in the trash, never in the compost pile.
• Avoid wounding the roots or stems of healthy plants during routine maintenance or transplanting.

Preventing it

• Inspect new plants carefully for any signs of swelling on the roots or crown before planting them.
• Avoid planting in areas where you have previously removed plants that suffered from crown gall.
• Minimize mechanical damage to the base of the plant when using lawn mowers or string trimmers.
• Choose resistant plant varieties whenever possible.

When to act

Act immediately upon spotting a gall to prevent the bacteria from spreading through the soil or via your tools. If the gall is on the main stem or crown, remove the entire plant promptly.

Questions people ask

Can I save a plant with crown gall?

If the gall is on a small, secondary branch, you can prune it out, but if the gall is on the main trunk or roots, the plant is usually lost.

Will the bacteria stay in my soil?

Yes, the bacteria can persist in the soil for several years, so it is best to avoid planting susceptible species in that same spot for a long time.

Is crown gall contagious to other plants?

It spreads through contact with contaminated soil or tools, so it is important to keep your equipment clean and avoid moving soil from infected areas.