Deep bark canker
Erwinia rubrifaciens
What is Deep Bark Canker (Brennaria rubrifaciens)?
Deep Bark Canker, caused by Brennaria rubrifaciens (formerly known as Erwinia rubrifaciens), is a plant disease that primarily affects trees. The disease primarily affects the Hartley cultivar. Symptoms include deep cracks and bleeding appearances on scaffolds and trunks, dark streaks in the inner bark, small dark spots in the wood, and gradual weakening of branches. Infections start on the lower part of the tree and progress upward over time. Deep bark canker does not extend into the rootstock and can further debilitate weakened trees.
How does Deep Bark Canker (Brennaria rubrifaciens) occur?
Deep Bark Canker, caused by Brennaria rubrifaciens, is primarily transmitted through symptomless graft wood used in tree propagation. The bacteria can also enter through deep wounds, such as shaker damage or woodpecker activity. The pathogen survives the winter in cankers or dried exudate on the tree surface and becomes active in late spring, oozing from the cankers. It can be spread to uninfected trees through windblown rain. Reproduction occurs when the bacteria infect the phloem tissue, impairing nutrient movement and gradually weakening the tree's branches.
Symptoms
1 - Impacts on Plants
• Brennaria rubrifaciens causes weakened branches, reduced productivity, and overall tree debilitation. • Infected trees may become more susceptible to sunburn injury and other infections. • If left untreated, the disease can spread and have long-term detrimental effects on tree health and productivity.
Solutions
1 - Cultural Practices
• Select disease-resistant tree varieties for planting. • Practice good sanitation by removing and destroying infected plant material. • Minimize injuries that expose the inner phloem. • Maintain proper water management and avoid both over- and under-irrigation. • Ensure proper fertilization and tree health through recommended practices.
2 - Pruning and Canopy Management
• Prune trees following recommended guidelines to improve air circulation. • Reduce canopy density to prevent the spread of disease. • Remove and destroy cankered branches. • Implement an Integrated Pest Management (IPM) program.
