Pacific Northwest 1998 An Online Guide to Plant Disease Control

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OSU Extension Office
 
Grape -- Crown Gall
 
Cause: Rhizobium vitis (formerly Agrobacterium vitis), a bacterium that attacks only grape and chrysanthemum. The bacterium survive for years in old galls, infected vines, and infected plant debris in the soil. It can enter the plant through wounds and often is already present in vascular tissues of symptomless grapevines. Although plants are systemically infected, with or without symptoms, the bacteria are rarely found in the green shoot tips of vines. Winter damage that causes wounds can trigger the infection process. After the bacterium enters a wound, a small piece of its DNA is transferred into the plant's DNA. The foreign DNA transforms normal plant cells in the wounded area into tumor cells. Once transformed, tumor cells proliferate automatically and produce unique substances that the bacteria can utilize readily. The result is a gall, a disorganized mass of hyperplastic and hypertrophic tissue. Crown gall is a greater problem on grafted vines than own rooted vines as the graft union can result in active gall growth even without winter freezes or mechanical damage. Grape production can drop by 40% on affected vines.
Symptoms: Fleshy galls typically are at the crown and on the first 2 feet of the vine above the soil line. Large galls may develop rapidly and completely girdle young vines in one season. Galled vines generally produce poor shoot growth, and vine portions above the galls may die. Few clusters develop on these shoots and if fruit do form they do not ripen. Galls are rarely seen on roots but the bacterium may cause areas of dark necrotic lesions on the roots.

Tumorous growth develops on trunks, often following cold injury.

The crown gall has a cauliflower-like growth and is solid when cut into with a pocket knife.

 
Cultural control:
  1. Plant pathogen-free nursery stock. The Northwest Grape Foundation Service in Washington cultures vines to be free of crown gall.
  2. Remove diseased vines including as much old root material as possible from the vineyard. Sterilize pruning tools between vines with 10% Clorox (bleach, which also will oxidize your pruning equipment) or shellac thinner (70% ethyl alcohol).
  3. Avoid any injury near the base of the vine.
  4. Control of soilborne nematodes may help reduce the incidence of plants with galls.
  5. If the gall is high enough on the trunk, a sucker replacement may be brought up from well below the galled areas in nongrafted plants.
  6. Soak dormant cuttings in hot water (129°F or 54°C) for 30 min. May help eliminate most of the bacteria (see reference). Primary buds are killed, but secondary buds grow out well. Some cultivars may be more sensitive than others.
  7. Use green shoot tips to propagate plants.
  8. Do not graft over to a new cultivar on vines that are exhibiting crown gall.
Chemical control: The efficacy of chemicals such as copper-based compounds, other chemicals and antibiotics is not satisfactory and thus not recommended.

  1. Gallex (ready to use) painted on very young galls to reduce further development. Galls may return the next year or, if treated late, may continue to develop. Tissue surrounding the gall may be injured especially on younger plants. Prepare the surface by removing soil from around the galled area, and allow the area to dry before applying. Not generally recommended for use. Not registered in Idaho. 12-hr reentry.
Biological control: Agrobacterium radiobacter K84 (Galltrol) is ineffective since it does not prevent infections.
References:
Burr, T.S., Bazzi, C., Sule, S., and Otten, L. 1998. Crown gall of grape. Biology of Agrobacterium vitis and the development of disease control strategies. Plant Disease 82:1288-1297.
Content edited by: Jay W. Pscheidt on January 1, 2009
 
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