HPIPM:Onion Pink Root

Taxonomy

Domain	Eukarya
Kingdom	Fungi
Phylum	Ascomycota
Subphylum	Pezizomycotina
Class	Dothideomycetes
Subclass	Pleosporomycetidae
Order	Pleosporales
Family	Phaeosphaeriaceae
Genus	Setophoma

Scientific Name

Setophoma terrestris

Scientific Name Synonyms

Phoma terrestris

Pyrenochaeta terrestris

Common Name

pink root rot

Author: Howard F. Schwartz and Michael E. Bartolo

Identification and Life Cycle

Pink root is caused by a soil-borne fungus, Phoma terrestris, which affects yield by reduced bulb size and aggravated losses from other diseases such as Fusarium basal rot. The fungus can survive for many years in a field, even in the absence of a host. There are reports of the pink root pathogen infecting roots of field corn. The pathogen can be spread within and between fields by cultivation equipment and irrigation water. Infection is favored by high soil temperatures (80°F).

Plant Response and Damage

Infected roots have a typical pink color, which turns to red, then purple, and finally brown to black. Severe infection may reduce the root system mass, and cause stressed leaf tips to turn yellow or tan and wilt. Yield losses of 20% or greater are possible when susceptible varieties are grown on infested soils.

Biological Control

Biological controls have not been developed for pink root.

Cultural Control

Practice a four-year or longer rotation to non-hosts such as small grains. Plant transplants and seed free of the pathogen in well-prepared seedbeds with adequate drainage. Avoid aggravating plant stresses such as soil compaction, root pruning during cultivation, and moisture extremes. Resistant varieties have been developed and should be planted in fields with a history of the disease. Avoid reuse of irrigation water, as the pathogen is readily moved in water.

Chemical Control

Chemical controls are most effective when combined with sound cultural practices. Fields can be quickly infested following fumigation.

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.