How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Gall formation is the typical symptom of this disease. Galls may be produced on canes, trunks, roots, and cordons and may grow to several inches in diameter. Internally galls are soft and have the appearance of disorganized tissue.

COMMENTS ON THE DISEASE

Agrobacterium tumefaciens is systemic in grapevine wood. The pathogen can be in plant debris from the vines that is buried in the soil where it can survive for several years. If new vines are planted they can be infected. Galls commonly develop where plants have been suckered or injured during cultivation or pruning. Galls frequently will appear where the vine tissue has been damaged by freezing temperatures. Natural growth cracks in woody root tissue also appear to be good sites for infection. The galls may girdle the vine and disrupt the flow of nutrients, thus restricting vine growth. If infested vines are field grafted or T-budded, gall formation may push the bud shield or graft union off the vine.

MANAGEMENT

Crown gall can be controlled by good sanitation, the avoidance of injury, and the avoidance of using wood systemically infected by the pathogen. Heat treatment of planting stock can eliminate the bacteria, but reinfection can occur once the vine is planted in the field. In areas where winter injury to the vines occurs, disease incidence will be high if the vines are infested. Grow tubes left on young vines over the winter may increase the incidence of crown gall in infected vines. Chemical treatments are generally not effective. Currently available products only treat the symptoms and do not eliminate the bacterial infection.

PUBLICATION

UC IPM Pest Management Guidelines: Grape
UC ANR Publication 3448
Diseases
W. D. Gubler, Plant Pathology, UC Davis
R. J. Smith, UC Cooperative Extension, Sonoma County
L. G. Varela, UC IPM Program, Sonoma County
S. Vasquez, UC Cooperative Extension, Fresno County
J. J. Stapleton, UC IPM Program, Kearney Agricultural Research Center, Parlier
A. H. Purcell, Environmental Science, Policy and Management, UC Berkeley
Acknowledgment for contributions to Diseases:
G. M. Leavitt, UC Cooperative Extension, Madera County

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