Agrobacterium vaccinii

Agrobacterium vaccinii is a pathogenic soil bacterium responsible for a condition known as crown gall or bacterial root gall in susceptible plant species. It belongs to the Rhizobiaceae family and is known for its unique ability to genetically transform plant cells, causing uncontrolled cell proliferation.

The primary host for this pathogen is the highbush blueberry (Vaccinium corymbosum). The bacteria invade the host through wounds, typically those caused by planting, root pruning, or damage from soil insects, effectively hijacking the host's cellular machinery to create a niche for their own survival.

Symptoms of the infection typically manifest as irregular, tumor-like growths known as galls on the roots or the base of the stem. These galls start as small, pale, and soft tissues but eventually harden, turn dark brown or black, and develop a rough, woody, or corky surface as they mature.

The disease cycle depends heavily on the presence of the pathogen in the soil and environmental conditions that support bacterial mobility. Wet, humid conditions, combined with soil temperatures conducive to microbial activity, facilitate the spread of the pathogen throughout the root zone of the host plant.

The economic impact of Agrobacterium vaccinii is significant, as infected plants suffer from impaired nutrient transport, leading to reduced vigor, chlorosis, diminished berry yields, and, in severe cases, the eventual death of the plant. Since there is no curative chemical treatment for infected plants, management focuses on strict prevention:

• Sourcing certified disease-free nursery stock for new plantings.
• Sanitizing pruning tools with appropriate disinfectants after every plant.
• Preventing physical injuries to the root system during cultivation and weeding.
• Prompt removal and destruction of symptomatic plants, including the surrounding soil.
• Maintaining optimal soil health and avoiding over-watering in infected areas.