Crown gall of grapevine

Allorhizobium vitis is the causal agent of crown gall, a destructive bacterial disease that affects grapevines globally. This pathogen belongs to the group of soil-borne bacteria that infect plants through wounds, inducing the formation of tumor-like growths known as galls by transferring T-DNA into the plant cells.

While the primary host is the common grapevine (Vitis vinifera), the bacterium can also be found in the rhizosphere of various other plants. It is highly persistent, capable of surviving in the soil for long periods or remaining latent within the woody tissues of the vine, often showing no visible symptoms for years.

The most prominent symptom is the development of galls on the vine trunk, cordons, and rootstocks. These galls are typically soft, white, or light-colored in the early stages, but as they age, they darken, become hard, and crack. In severe cases, the galls can girdle the plant, blocking the transport of water and nutrients, which leads to stunted growth and reduced fruit yield.

Disease development and spread are strongly associated with environmental conditions and plant injury. Cold damage, which causes bark splitting, is a primary entry point for the bacterium. Furthermore, contaminated nursery stock is the most common way of introducing the pathogen into a new vineyard, while pruning tools serve as mechanical vectors during routine maintenance.

The economic impact of crown gall is significant, as it leads to the gradual decline and eventual death of infected vines. Since there is no cure for this bacterial infection, management focuses exclusively on prevention. Key strategies include:

• Sourcing certified pathogen-free planting material.
• Sanitizing pruning tools with alcohol or bleach solutions between vines.
• Protecting vines from winter cold damage.
• Removing and destroying severely infected vines to reduce inoculum levels.