- Worldwide distribution. On lettuce. An important disease.
- A fungus producing large spots between the veins which dry and fall out. Fruiting bodies filled with spores occur in the spots. Spread occurs in rain-splash, wind-driven rain, and in infected seed.
- Worse during periods of high rainfall when spots merge to destroy leaves and reduce quality.
- Cultural control: use certified seed; check plants in the nursery for leaf spots; use drip rather than overhead irrigation; collect debris and incorporate into soil or burn; 3-year crop rotation.
- Chemical control: use copper or mancozeb; if systemic products needed, use triazoles.
Pacific Pests, Pathogens, Weeds & Pesticides
Lettuce Septoria leaf spot & blight (150)
Photo 1. Light brown irregular spots of Septoria lactucae between the veins are the first signs of lettuce leaf spot.
Photo 2. Advanced stage of Septoria leaf spot, Septoria lactucae. The black dots are the fruiting bodies of the fungus (pycnidia). Often the dead areas dry and fall out.
Lettuce leaf spot and blight; Septoria spot, Septoria leaf spot
AUTHOR Grahame Jackson
Information (and Photo 3) from Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany; and Lettuce, Septoria blight (undated). The Center for Agriculture, Food, and the Environment. University of Massachusetts Amherst. (https://ag.umass.edu/vegetable/fact-sheets/lettuce-septoria-blight); and (including Photos 1&2) from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al.. CSIRO Publishing.
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.