Photo 1. Roughly circular leaf spots, with concentric rings, mostly between the veins on cabbage caused by black leaf spot, Alternaria brassicicola.
Photo 2. Cabbage leaf spot, possibly Alternaria brassicicola, showing dark brown areas where spores are forming, and a large spot (lower left) with a crack in the centre; later, the crack will widen and the centre of the spot will fall out becoming similar to Photo 5.
Photo 4. Single leaf spot on a cabbage leaf caused by Alternaria brassicicola, showing the "shot-hole" effect: the centre of the spot rots and falls out. A yellow margin or halo is also seen.
Cabbage black leaf spot
Alternaria brassicicola. Another Alternaria fungus, Alternaria brassicae, grey leaf spot, also occurs, and causes similar symptoms (see Fact Sheet no. 310). Microscopic examination of the spores is needed to distinguish between the two species (Photo 5).
AUTHOR Grahame Jackson
Information (and Photo 1) from Gerlach WWP (1988) Plant diseases of Western Samoa. Samoan German Crop Protection Project, Deutsche Gesellschaft für Technische Zusammenarbeit (GTZ) Gmbh, Germany; and (with Photo 4) from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, Tony Cooke, Susan House. CSIRO Publishing; Photo 4 Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org. Photos 5 (taken by Eric McKenzie), and used in this fact sheet, appeared previously in McKenzie E (2013) Alternaria brassicicola. Available online: 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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