Pacific Pests & Pathogens - Mini Fact Sheet EditionCabbage grey leaf spot (310)
Pacific Pests & Pathogens - Mini Fact Sheet EditionCabbage grey leaf spot (310)
Summary
- Worldwide distribution. On plants in the cabbage family, especially Chinese cabbage and mustards. Important fungal disease, simlar to cababge black leaf spot (see Fact Sheet no. 133).
- Damage: i) seed infections cause pre- and post-emergence damping-off (see Fact Sheet no. 47); ii) seed infection; and iii) spots on head and/or outer leaves unsightly reducing quality and shelf life.
- Grey leaf and stem spots, circular or irregular, mostly between veins, up to 25 mm diameter, with concentric rings, producing spores below. Centre of spots fall out with age.
- Dark, sunken rots occur on heads of broccoli and cauliflower.
- Spread by water splash, in wind-driven rain, on seed.
- Cultural control: seed - hot water (50°C for 25-30 mins.); nursery hygiene: clean trays, pasteurise soil or use soilless mixes, and discard infected seedlings; weed; space plants to allow air movement; avoid overhead irrigation; collect and destroy debris after harvest; crop rotation.
- Chemical control: seed - captan or thiram; field - chlorothalonil, copper or mancozeb.
Common Name
Cabbage grey leaf spot
Scientific Name
Alternaria brassicae. Another Alternaria fungus, Alternaria brassicicola, cabbage black leaf spot, also occurs, and causes similar symptoms (see Fact Sheet no. 133). Microscopic examination of the spores is needed to distinguish between the two species (Photo 4).
AUTHOR Grahame Jackson and Eric McKenzie
Information from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, Tony Cooke, Susan House. CSIRO Publishing; and from Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany. Photo 1 Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org. Photo 2 Yuan-Min Shen, Taichung District Agricultural Research and Extension Station, Bugwood.org. Photo 3 Howard F. Schwartz, Colorado State University, Bugwood.org. Photo 4 (taken by Eric McKenzie), and used in this fact sheet, appeared previously in McKenzie E (2013) Alternaria brassicae PaDIL - (http://www.padil.gov.au).
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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