Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Watermelon gummy stem blight (007)

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  • Worldwide distribution. On watermelon, cantaloupe melon and cucumber (see Fact Sheet no. 201). An important disease.
  • Spots on leaves grow rapidly, leaves blacken shrivel and die. Spots on vine leak a gummy (sticky) liquid.
  • Spread as spores from black sacs on the leaf spots in wind and rain.
  • Cultural control: site nursery away from production areas; pasteurised soil or soilless mixes; check each seedling for spots, and discard if seen; 3-year rotation; do not plant next to diseased watermelon crops; collect and destroy trash after harvest.
  • Chemical control: coppers, mancozeb, or chlorothalonil every 7-10 days, depending on weather.
Common Name

Gummy stem blight

Scientific Name

Stagonosporopsis cucurbitacearum; (previously, Didymella bryoniae). Also known by the asexual state, Phoma cucurbitacearum or Ascochyta cucumis. The latter is commonly found on plants in the field producing minute oval spores in round black structures in the leaf called 'pycnidia' that are just visible to the naked eye.

AUTHORS Helen Tsatsia & Grahame Jackson
Information from CABI (2019) Didymella bryoniae (gummy stem blight of cucurbits). Invasive Species Compendium. (; and from DAF (2016) Gummy stem blight. Queensland Government. (

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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