Burkholderia cepacia

Systematic position and pathogen type: Burkholderia cepacia belongs to the Kingdom Bacteria and the genus Burkholderia. It is a Gram-negative, aerobic, rod-shaped bacterium that is part of the Burkholderia cepacia complex (BCC). In agriculture, it is classified as a versatile phytopathogen, capable of surviving in diverse environments, including soil, water, and the rhizosphere of various host plants.

Diseases and host crops: This pathogen is widely recognized for causing soft rots in a variety of vegetables. It is particularly notorious for causing "sour skin" in onions and garlic, leading to the rapid decay of succulent scales. Beyond alliums, it affects a broad range of crops, including tomatoes, cucumbers, potatoes, and carrots, often compromising the shelf life and quality of the produce in storage facilities.

Biology and life cycle: The life cycle involves colonization of plant surfaces followed by systemic infection through natural openings or wounds. Once inside, the bacterium utilizes a range of extracellular enzymes, such as pectinases and cellulases, to break down plant tissues. This process leads to tissue maceration and the characteristic foul-smelling rot associated with advanced stages of the infection.

Development and spread: Burkholderia cepacia thrives in environments with high humidity and temperatures between 20°C and 30°C. It is an extremely resilient organism, capable of forming biofilms that protect it from environmental stressors and antimicrobial agents. Transmission primarily occurs through water splashing, contaminated agricultural tools, and handling during harvest, which creates new entry points for the bacteria.

Damage and control measures: The primary economic impact is post-harvest loss, which can be devastating if storage conditions are not strictly managed. Management strategies include:

• Maintaining strict sanitation protocols in storage facilities.
• Implementing effective crop rotation cycles to reduce soil-borne inoculum.
• Preventing mechanical injury to produce during harvest and transport.
• Ensuring optimal ventilation and cooling in storage environments to inhibit bacterial growth.
• Applying copper-based bactericides as a preventive measure in high-risk areas.