# Crown gall

- URL: https://backyardgrapes.com/diseases/crown-gall/
- Scientific name: Agrobacterium vitis
- Category: Bacterial
- Affects: Trunk & cordons
- Severity: moderate
- Favored by: Enters through freeze cracks and wounds; worse in cold-winter areas.
- Easily confused with: Esca (trunk disease)

**Summary:** Warty, tumour-like growths on the trunk near the soil line, often after winter injury.

**What to look for:**
- Soft, fleshy, cream-to-brown tumours (galls) on the trunk, crown, or graft union.
- Galls often form in a line where the bark froze and split.
- Older galls turn dark, hard, and corky.
- Girdling galls weaken or kill the vine above them.

**Treatment — Cultural / prevention:**
- Plant clean, certified nursery stock — the bacterium is often carried in.
- Protect trunks from winter freeze injury (hilling up, trunk wraps, multiple trunks).
- Avoid wounding the lower trunk; train several trunks so one can be replaced.
- Remove severely galled vines; the bacterium persists in soil and old roots.

**Treatment — Organic / low-toxicity:**
- No spray cures established galls; prevention of injury is the real control.

**Treatment — Conventional (chemical):**
- None effective once galls have formed.

Crown gall is caused by the bacterium *Agrobacterium vitis*, which lives
systemically inside the vine and in the soil. It only produces its characteristic
tumours where the tissue has been wounded — most often along cracks left by winter
freeze injury near the soil line.

Because the bacterium is already inside many infected vines, there is no spray that
cures it. The practical strategy for home growers is to start with clean plants,
prevent freeze damage, and grow multiple trunks so a galled trunk can simply be cut
out and replaced by a healthy one.

**Image credits:**
- Crown gall on the graft union and trunk of a grapevine — [Rutgers Plant & Pest Advisory](https://plant-pest-advisory.rutgers.edu/crown-gall-in-grapevines-early-symptoms-and-management/)
- Crown gall on a grape trunk — [Purdue University, Facts for Fancy Fruit](https://fff.hort.purdue.edu/article/crown-gall-of-grape-vines/)
- Muscat of Alexandria grapevine with crown gall tumors, southern San Joaquin Valley — [Rochester Institute of Technology (RIT News)](https://www.rit.edu/news/researchers-gain-new-insight-about-bacteria-within-grapevine-killing-crown-gall-tumors)

**Sources:**
- [Crown Gall / Grape / Agriculture: Pest Management Guidelines](https://ipm.ucanr.edu/agriculture/grape/crown-gall/) — UC Statewide IPM Program (UC ANR)
- [Grape Crown Gall (Agrobacterium vitis) - NYS IPM Fact Sheet](https://ecommons.cornell.edu/handle/1813/43100) — Cornell University / New York State IPM Program
- [Bacterial Crown Gall of Fruit Crops](https://ohioline.osu.edu/factsheet/plpath-fru-19) — Ohio State University Extension