Crown gall
Agrobacterium tumefaciens
Also Known As - Bacterial gallWhat is crown gall (agrobacterium tumefaciens)?
Crown gall is a plant disease caused by the soil-inhibiting bacterium Agrobacterium tumefaciens. It is distributed worldwide and affects a wide range of plants, including fruit trees (e.g., apple, pear), nut trees (e.g., almond, walnut), ornamental plants (e.g., roses, chrysanthemums), vines (e.g., grapevines), and field crops (e.g., cotton, tomatoes). The disease is identified by the presence of galls, and overgrowths, on roots and at the base of woody plants. These galls can also appear on stems and leaves. Crown gall can lead to stunted growth, reduced yield, and weakened plants.
How does crown gall (Agrobacterium tumefaciens) occur?
Crown gall occurs when plants become infected with Agrobacterium tumefaciens. The bacterium enters the plant through wounds or natural openings and transfers its DNA, known as T-DNA, into the plant cells. This DNA becomes integrated into the plant's genetic material, causing the cells to divide uncontrollably and resulting in the formation of galls. The infection can spread within the plant and to other plants through various means such as soil, water, or infected plant parts.
Symptoms
1 - Plant health
• Crown gall can weaken infected plants, leading to stunted growth, reduced yields, and even plant death in severe cases. • Crown gall can result in significant economic losses in agricultural systems, affecting crop productivity and marketability.
2 - Soil contamination
The bacterium can persist in the soil for several years, especially when infected plant material or root exudates are present. This increases the risk of future infections in susceptible plants.
3 - Environmental implications
The presence of disease can disrupt natural ecosystems and plant communities, particularly if susceptible plant species are prevalent.
Solutions
1 - Prevention
• Choose disease-resistant plants for cultivation. • Practice good hygiene by sterilizing pruning tools and equipment. • Apply protective wound dressings on plant wounds. • Maintain proper soil drainage and fertility. • Avoid consecutive planting of susceptible crops. • Remove and destroy infected plants. • Utilize biological agents for disease suppression.
2 - Chemical Control and Biocontrol
• Consult with local agricultural extension services for chemical control options. • Chemical control options for crown gall include Agrobacterium radiobacter strain K84, copper-based fungicides, and antibiotics like streptomycin or tetracycline. • Biocontrol products like Bacillus subtilis-based products, Trichoderma spp., and Pseudomonas fluorescens-based products can also be used.
