- Worldwide distribution. On onion, leek, Welsh onion (Japanese bunching onion), Chinese chive, shallot. A cosmetic disease.
- On the lower parts of the outer leaves and neck, in patches or rings.
- Spore masses with long stiff hairs. Spots on leaves turn to blights under wet warm conditions.
- More serious rots occur if onions harvested wet and stored moist >20°C.
- Causes a seedling damping-off.
- Spread occurs in wind-driven rain.
- Cultural control: well-drained soil; clean seed and healthy transplants; avoid harvesting in wet weather; cure bulbs quickly and store cool and dry; plant those with coloured outer scales; 2-3-year crop rotations.
- Chemical control: possibly, mancozeb, or chlorthalonil.
Pacific Pests, Pathogens, Weeds & Pesticides
Onion smudge (186)
Smudge of onion bulbs, anthracnose of onions
AUTHOR Grahame Jackson
Information from Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al. CSIRO Publishing; and CABI (2021) Onion Smudge (Colletotrichum circinans) Plantwise Knowledge Bank. (http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=14897); and from Rollins J (2014) Colletotrichum circinans. BugwoodWiki. (http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=14897). Photo 1 Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org. Photo 2 Diseases of vegetable crops in Australia (2010). Editors, Denis Persley, et al. CSIRO Publishing. Photo 3 Cesar Calderon, USDA APHIS PPQ, Bugwood.org.
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.