HPIPM:Onion Smudge

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Ascomycota
Subphylum	Pezizomycotina
Class	Sordariomycetes
Subclass	Hypocreomycetidae
Order	Glomerellales
Family	Glomerellaceae
Genus	Colletotrichum

Scientific Name

Colletotrichum circinans

Scientific Name Synonyms

Colletotrichum dematium f. circinans

Vermicularia circinans

Common Name

onion smudge

Author: Howard F. Schwartz and Michael E. Bartolo

Smudge, or anthracnose is caused by Colletotrichum circinans (Berk.) Voglino which primarily affects white onions at harvest and during storage. Small dark green or black spots appear around the neck and on outer scales, often in concentric rings. These spots may spread on inner scales and form small yellow lesions. The fungus can survive on onion debris and in soil for several years. Infection is favored by warm (80° F) moist weather, especially near harvest.

Disease management recommendations include crop rotation out of onions for three years; use clean seed and non-infected transplants; good drainage; timely applications of fungicides such as mancozeb (Manzate), chlorothalonil (Bravo), and iprodione (Rovral); let onions dry out completely at harvest and/or heat treat before storing; store dry onions at 32° F and less than 70 percent relative humidity.

Due to constantly changing labels, laws and regulations, the sponsors of this web site assume no liability for the suggested use of any chemicals noted in the management section. Contact your local pest management personnel for current information on labeled pesticides that can be used for the intended plant disease, insect pest or weed.