Backyard Grapes Identify & treat grapevine problems
Bacterial moderate severity

Crown gall

Agrobacterium vitis

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

Crown gall on the graft union and trunk of a grapevine Rutgers Plant & Pest Advisory
Crown gall on a grape trunk Purdue University, Facts for Fancy Fruit
Muscat of Alexandria grapevine with crown gall tumors, southern San Joaquin Valley Rochester Institute of Technology (RIT News)

Description

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.

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 options

Cultural & prevention

Start here — habits that stop problems before they spread.

  • 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.

Organic / low-toxicity

Gentler sprays and biologicals for active outbreaks.

  • No spray cures established galls; prevention of injury is the real control.

Conventional fungicide / pesticide

For severe cases. Always follow the product label.

  • None effective once galls have formed.

Sources

This entry is based on the references below. Read them for full detail and for spray timings and rates valid where you live.

  1. Crown Gall / Grape / Agriculture: Pest Management Guidelines — UC Statewide IPM Program (UC ANR)
  2. Grape Crown Gall (Agrobacterium vitis) - NYS IPM Fact Sheet — Cornell University / New York State IPM Program
  3. Bacterial Crown Gall of Fruit Crops — Ohio State University Extension