Watermelon bacterial fruit blotch

Bacterial fruit blotch, often identified in the field as watermelon green spot or blotch, is a highly destructive disease caused by the seed-borne bacterium Acidovorax citrulli. This pathogen poses a significant threat to global cucurbit production, capable of causing devastating crop losses in both field and greenhouse conditions.

The disease primarily targets watermelon, melon, and cucumber plants. Once established, the bacteria can infect the plant at any growth stage, significantly impacting the vegetative biomass and making the resulting fruits completely unmarketable due to severe necrotic lesions.

Symptoms often manifest as small, greasy, water-soaked spots on the leaves, which later develop into larger dark brown lesions. On the fruit, the disease appears as dark, firm, slightly sunken areas that can eventually crack, allowing secondary pathogens to enter and initiate the decay process.

Environmental conditions such as high humidity, frequent rainfall, and moderate temperatures provide ideal conditions for bacterial multiplication and transmission. The pathogen can survive in seeds and volunteer plants, spreading rapidly through splash dispersal, contaminated irrigation water, and infected tools used during cultivation.

• Sourcing certified disease-free seeds from reputable suppliers.
• Implementing strict field sanitation and removing infected plants immediately.
• Practicing long-term crop rotation with non-cucurbit species.
• Applying preventative copper-based bactericides during high-risk periods.
• Managing irrigation systems to keep foliage dry and minimize water splashing.