Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Watermelon fruit blotch (196)

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  • Widespread. Not reported from Africa. On cucurbits, including wild species. An important bacterial disease. More serious on watermelon.
  • Greyish spots on seedlings; those on stem cause death. Fruit infections occur early with dark green areas near harvest, superficial at first, later cracking.
  • Spread from seed to leaves and then in wind and rain.
  • Cultural control: certified seed; 2-year crop rotation; check seedlings; disinfect nursery after outbreaks (bleach); grow new crops far from other cucurbits; remove volunteers; use drip irrigation; clean equipment used in diseased fields; tolerant varieties; collect and burn debris after harvest.
  • Chemical control: copper, if symptoms seen early.
Common Name

Fruit blotch; it is also known as bacterial fruit blotch.

Scientific Name

Acidovorax citrulli; previously this bacterium was named Acidovorax avenae subsp. citrulli, and when first isolated from watermelon, it was Pseudomonas pseudoalcaligenes subsp. citrulli. Several strains exist.

AUTHOR Grahame Jackson
Information from CABI (2019) Acidovorax citrulli (fruit blotch) Crop Protection Compendium. (; and Acidovorax citrulli. Wikipedia. (; and from Islam MR (2019) Development of molecular markers for detection of Acidovorax citrulli strains causing bacterial fruit blotch disease in melon. International Journal of Molecular Sciences 20(11):2715. Photo 1 Gerald Holmes, California Polytechnic State University at San Luis Obispo, Photo 2 George Wall, formerly CALS/AES University of Guam. Photo 3 Jason Brock, University of Georgia,

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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