Burkholderia gladioli

Systematic position and nature of the pathogen: Burkholderia gladioli is a Gram-negative, aerobic, rod-shaped bacterium belonging to the kingdom Bacteria, family Burkholderiaceae, and genus Burkholderia. This soil-borne phytopathogen is highly versatile, capable of surviving as a saprophyte in the soil, yet becoming a destructive plant pathogen under favorable environmental conditions.

Diseases and susceptible crops: The bacterium is responsible for severe diseases such as bacterial scab and soft rot. It primarily affects bulbous and cormous plants, including gladiolus, iris, and narcissus. Additionally, it causes significant damage to various crops like onions, garlic, and maize, manifesting as water-soaked lesions, tissue softening, and eventual necrosis that ruins both vegetative parts and stored produce.

Biology and disease cycle: The pathogen survives in infested soil and within dormant infected bulbs or corms. Transmission occurs mainly through contaminated water, tools, or direct contact during planting and harvesting. The bacteria exploit microscopic wounds on roots or bulbs to enter host tissues, where they secrete pectinolytic enzymes that degrade cell walls, leading to rapid colonization and lesion expansion.

Developmental conditions and impact: Disease development is heavily dependent on moisture and temperature. High humidity combined with temperatures between 20°C and 30°C creates optimal conditions for bacterial proliferation. The economic impact is severe, as the pathogen can cause total loss of nursery stock during storage, making infected batches unsellable and posing a risk of contamination to surrounding healthy plants.

Protection and control measures: Effective management of Burkholderia gladioli requires an integrated approach focusing on prevention and sanitation:

• Utilizing certified disease-free planting material.
• Implementing strict crop rotation protocols (3-5 years) to reduce soil inoculum levels.
• Proper sanitation of equipment, storage facilities, and processing tools.
• Treating bulbs/corms with hot water or registered bactericides before storage.
• Managing insect vectors that cause wounding, as they provide entry points for the bacteria.