Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Cabbage black leaf spot (133)

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  • Worldwide distribution. Temperate as well as tropical countries. Members of cabbage family, including broccoli, cabbage, cauliflower, mustard, oilseed rape, and cruciferous weeds are hosts, including weeds. An important disease, although the spots are mainly on the outer leaves which are removed before sale.
  • Spots with ring patterns, and dark spore masses on underside of leaves. Spots fall out when old. Rots occur on heads of broccoli and cauliflower. Worse in cool areas.
  • Seed infection causes damping-off, and lower quality.
  • Spread in water splash, wind-driven rain, and in 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 - copper, mancozeb, chlorothalonil.
Common Name

Cabbage black leaf spot

Scientific Name

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 (including Photo 4) Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al. CSIRO Publishing; and Seemadua S, et al. (2011) Alternaria spot (Alternaria brassicicola): PaDIL -; and from (including Photos 5) McKenzie E (2013) Alternaria brassicicola: PaDIL - ( Photo 4 Gerald Holmes, California Polytechnic State University at San Luis Obispo,

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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