Your are here:

Potato ring rot

Scientific Name
Clavibacter michiganensis subsp. sepedonicus
Scientific Author
(Spieckermann & Kotthoff 1914) Davis, Gillaspie, Vidaver & Harris 1984
Exotic species - absent from Australia

Page menu options:

Diagnostic Images

Image Options
Diagnostic Images (17)
Diagnostic Notes

The disease causes wilting of potato plants late in the season and tuber rotting in field and store. A rot appears in the vascular ring of the tuber, which can be seen when tubers are cut across near the heel end. First the tissue appears glassy and water soaked, becoming later brown to black in colour and even disintegrate. Bacterial ooze leaking from the vascular ring of diseased tubers is typical. If the disease intensity is high, the tuber skin can crack. Wilting of plants is usually slow, initially limited to the leaf margins and discoloration of the vascular tissue on stems is not obvious. Symptoms can be confused with other diseases or natural senescence. This pathogen can cause asymptomatic infections and atypical symptoms. For additional information see EPPO (2006), the Crop Protection compendium (2005) and the web links.

The bacteria:

Gram-positive, non-motile, non-sporing, pleomorphic rods, obligate aerobes. A detailed description of C. michiganensis subsp. sepedonicus is given by Bradbury (1986) and Davis et al. (1984).


1. Whereas the primary source of C. michiganensis subsp. sepedonicus is infected tubers and its potential for loss is so great, The only reliable control for the disease is avoidance and clean seed materials. Seed certification with a zero tolerance for the disease is usually enforced.

2. According to Christie et al. (1991), the insects Colorado potato beetle (Leptinotarsa decemlineata), green peach aphid (Myzus persicae) and the aster leafhopper (Macrosteles fascifrons) can transmit this disease.

3. PCR-based identification methods for this pathogen have been developed (Mills et al. 1997, Lee et al. 1997, 2001, Schaad et al. 1999, Baer et al. 2001, van Beckhoven et al. 2002, Rivas et al. 2002).

4. Comprehensive details of the identification of C. michiganensis subsp. sepedonicus using multiple techniques can be found in the European and Mediterranean Plant Protection Organization (2006).
More Information
Specimen Contact
Dr Jose R. Liberato
Liberato JR, Gudmestad NC & De Boer SH
31/07/2006 03:53 AEST
Last Updated
28/07/2016 08:23 AEST
Liberato JR, Gudmestad NC & De Boer SH (2006) Potato ring rot (Clavibacter michiganensis subsp. sepedonicus ) Updated on 7/28/2016 8:23:44 AM Available online: PaDIL -
Image Use
Free for use under the Creative Commons Attribution 3.0 Australia License