Bacterial blight

Bacterial blight, caused by the pathogen Erwinia chrysanthemi (now taxonomically classified as Dickeya dadantii), is a destructive plant disease known for causing systemic wilting and soft rot. The bacteria produce powerful enzymes that degrade plant cell walls, leading to the rapid collapse of internal structures and cell death.

This pathogen exhibits a broad host range, posing a significant threat to various agricultural and ornamental species. Key crops vulnerable to infection include celery, oats, hemp, Arabica and Robusta coffee, hazelnuts, soybeans, and cotton, among others, making it a major concern in diverse farming systems.

Symptoms typically start as wilting or drooping of leaves, particularly during the hottest parts of the day. As the disease progresses, internal tissues of the stems and roots undergo necrosis and become soft, watery, and often emit a foul odor due to bacterial degradation. Vascular tissues may show distinct brown discoloration when cross-sectioned.

The development and spread of Erwinia chrysanthemi are strongly favored by high temperatures (25–30°C) and excessive moisture. The bacteria thrive in water films on leaf surfaces or in saturated soil, spreading easily through irrigation, rain splash, contaminated tools, and infected propagation material like cuttings or seeds.

• Utilize only pathogen-free, certified seeds and cuttings.
• Implement strict sanitation measures for all agricultural equipment and tools.
• Rotate crops to break the life cycle of the bacteria in the soil.
• Improve drainage systems to prevent waterlogging and reduce humidity.
• Manage insect vectors that contribute to the mechanical transmission of the pathogen.

The economic impact of bacterial blight can be devastating, leading to total crop loss if conditions are ideal for the pathogen. Because chemical control options are limited and often ineffective once systemic infection occurs, prevention through quarantine and rigorous farm hygiene remains the most effective management strategy.