Acidovorax citrulli

Acidovorax citrulli is a seed-borne gram-negative bacterium belonging to the Kingdom Bacteria, genus Acidovorax, and species Acidovorax citrulli. It is recognized globally as the primary agent responsible for Bacterial Fruit Blotch (BFB), a devastating disease affecting various members of the Cucurbitaceae family.

The primary hosts of this pathogen include watermelon, melon, cucumber, and pumpkin. In infected plants, the pathogen causes distinct watery lesions on foliage and severe, dark, greasy-looking necrotic spots on the fruit surface. Once the fruit is infected, it quickly loses market value, often resulting in complete crop loss.

The biological cycle of this bacterium is heavily dependent on contaminated seeds and latent survival in infested plant debris. The pathogen colonizes the seed coat and can enter the plant during germination. Once established, it spreads rapidly through splashing water, overhead irrigation, and handling during field maintenance.

Optimal environmental conditions for the proliferation of Acidovorax citrulli include high relative humidity and warm temperatures ranging between 25°C and 30°C. In such conditions, the latent phase of the pathogen shortens, allowing the bacteria to move from primary infection sites to colonize entire fields efficiently.

Management and control strategies must be multifaceted due to the bacterium's resilience. Key approaches include:

• sourcing pathogen-free certified seeds;
• implementing rigorous seed disinfection protocols;
• applying strict crop rotation practices;
• ensuring effective weed management;
• utilizing copper-based bactericides for preventative field applications.