Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Cucurbit leaf spot (145)

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  • Worldwide distribution. On watermelon (and squash), and other members of the cucumber family, including weeds. A minor disease, worse under shade.
  • Small, about 5 mm, round spots with grey centres, brown margins, and sometimes yellow halos. Centres may fall out, spots merge, resulting in black areas, and leaf fall.
  • Spores on the underside of the leaves are spread in wind and rain.
  • Cultural control: do not plant new crops next to old; use 3-4-year rotation; weed; do not grow watermelon under shade; collect and burn trash after harvest. Chemical control: copper, chlorothalonil, or mancozeb.
Common Name

Cercospora leaf spot

Scientific Name

Cercospora citrullina: note, previously this has been a name for Dydymella bryonae (now Stagonosporopsis cucurbitacearum) (see Fact sheet nos. 07 & 201)

AUTHOR Grahame Jackson
Information from Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany; and Schwartz, Gent DF (2007) Cercospora leaf spot (cucumber, melon, pumpkin, squash, and zucchini). High Plains IPM Guide, a cooperative effort of the University of Wyoming, University of Nebraska, Colorado State University and Montana State University. (; and Cucurbit diseases (undated) Cercospora leaf spot. UF/IFAS. University of Florida. ( Photos 1&2 Gerald Holmes, Valent USA Corporation,

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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