- Worldwide distribution. Tropics and sub-tropics. On lettuce, and relatives in daisy family, including weeds. Occasionally, an important disease.
- Spots circular to oval, brown, with whitish centres, up to 1 cm. Later, merge. On older leaves first.
- Wet weather disease; spores spread in wind and rain.
- Cultural control: in nurseries – keep free of weeds and avoid overcrowding; in field – space plants to allow air movement; drip irrigation; weed; 2-3-year crop rotation; avoid overlapping crops; collect and burn trash after harvest.
- Chemical control: likely that cultural practices sufficient; if fungicide needed, use mancozeb.
Pacific Pests, Pathogens, Weeds & Pesticides
Lettuce Cercospora leaf spot (210)
Photo 1. Lettuce leaf spot, Cercospora lactucae-sativae. Some spots have joined together, especially at the margins.
Lettuce leaf spot
Cercospora lactucae-sativae; previously known as Cercospora longissima. It is closely related to Cercospora apii.
AUTHOR Grahame Jackson
Information from McKenzie E (2013) Cercospora lactucae-sativae: PaDIL - http://www.padil.gov.au. Photos 1&2 Kohler F, et al. (1997) Diseases of cultivated crops in Pacific Island countries. South Pacific Commission. Pirie Printers Pty Limited, Canberra, Australia.
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.