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Bacteria - sweetpotato

Contributors to this section: CIP, Lima, Peru (Carols Chuquillanqui, Segundo Fuentes, Ivan Manrique, Giovanna Muller, Willmer Pérez, Reinhard Simon, David Tay, Liliam Gutarra); CIP, Nairobi, Kenya (Ian Barker); FERA, UK (Derek Tomlinson, Julian Smith, David Galsworthy, James Woodhall).

Bacterial stem and root rot

Scientific name

Dickeya chrysanthemi (Burkholder et al., 1953) Samson et al., 2005, comb. nov.


EPPO A2 quarantine organism.
Erwinia chrysanthemi has been reclassified into six new Dickeya species (Samson et al., 2005). The revised nomenclature of these pathogens has distinguished them from other soft rot erwiniae (including P. atrosepticum and P. carotovorum). Different biovars of D. chrysanthemi have been characterized by biochemical, physiological, serological, molecular and pathogenicity tests.


Foliage: Symptoms are yellow leaves and dark green to black, water-soaked lesions on stems and petioles. Usually, only one or two branches collapse and died, but occasionally the entire plant can be killed. Internally, black streaks are evident in the vascular system of both stems. Localized lesions on fibrous roots may also be present.

Roots: Many roots of diseased plants are rotted in the ground but important losses are produced during transport, storage or market. On fleshy roots, localized lesions with black margins can be observed on the surface, but more frequently the rotting is internal, with no evidence outside. (Ames et al., 1997; Schaad and Brenner, 1977; Harrison et al., 2006)


Dickeya chrysanthemi strains have been isolated from a number of different hosts in different countries (CABI, 2007). Chrysanthemum, daisy, tobacco, pepper, tomato, Irish potato, cabbage, eggplant, soybean, petunia, African violet, morning-glory and Cuscuta sp. have been reported susceptible to this bacteria (Schaad and Brenner, 1977).

Geographic distribution

Asia, Europe, Africa, North America, Central America, South America, Oceania.

Biology and transmission

The bacteria can penetrate and enter the plant through wounded tissue on stem cuttings and can invade stems and the branches. The entire plant can be killed and roots can be rotted (Duarte and Clark, 1993).

Detection/indexing method in place at the CGIAR Center

  • Crystal violet pectato (CVP) medium for detection and isolation of D. chrysanthemi (Pérombelon and Burnet (1991).
  • Modified Kelman’s without Tetrazolium chloride (CPG) medium for detection and isolation of D. chrysanthemi (French et al., 1995).


  • In seed certification schemes, neither virus nor bacteria infections must be tolerated during the growing season. Stocks of in vitro cultures used for propagation should be from pathogen-free plants and maintained under conditions designed to prevent infection and contamination.

Procedure followed at CIP in case of a positive test

  • At CIP if the pathogen is detected the imported germplasm must be cleaned by thermotherapy.

References of protocols at EPPO, NAPPO or other similar organization

OEPP/EPPO. 1982. Data sheets on quarantine organisms. No. 53. Erwinia chrysanthemi. Bulletin OEPP/EPPO Bulletin 12 (1).

OEPP/EPPO. 1988. A1 and A2 lists of quarantine pests. Specific quarantine requirements. EPPO Publications Series B No. 92.

References and further reading

Ames T, Smit NEJM, Braun AR, O'Sullivan JN, Skoglund LG. 1997. Sweetpotato: Major pests, diseases, and nutritional disorders. International Potato Center.Lima, Peru. 1997. 153 p.

CABI 2007. Crop Protection Compendium. [online] Available from URL: Commonwealth Agricultural Bureau International (CABI), Wallingford, UK. Date accessed 10 May 2010

Clark CA, Moyer JW. 1991. Compendium of Sweet Potato Diseases. Centro Internacional de la Papa (CIP). Lima, Peru. 97 p.

Duarte V, Clark CA. 1992. Presence on sweetpotato through the growing season on Erwinia chrysanthemi, cause of stem and root rot. Plant Dis. 76:67–71.

Duarte V, Clark CA. 1993. Interaction of Erwinia chrysanthemi and Fusarium solani on sweetpotato. Plant Dis. 77:733–735.

French ER, Gutarra L, Aley P, Elphinstone J. 1995. Culture media for Pseudomonas solanacearum: isolation, identification and maintenance. Fitopatologia 30, 126-30.

Harrison Jr HF, Peterson JK, Snook ME. 2006. Sweetpotato storage root phenolics inhibit in vitro growth of Erwinia chrysanthemi. Allelopathy Journal. 17(l):81–88.

Moyer JW, Jackson GVH, Frison EA. (eds.). 1989. FAO/IBPGR Technical Guidelines for the Safe Movement of Sweet Potato Germplasm. Food and Agriculture Organization of the United Nations. Rome/International Board for Plant Genetic Resources, Rome.

Pérombelon MCM, Burnett EM. 1991. Two modified crystal violet pectate (CVP) media for detection, isolation and enumeration of soft rot erwinias. Potato Research 34: 79-85.

Samson R, Legendre JB, Christen R, Fischer-Le Saux M, Achouak W, Gardan L. 2005. Transfer of Pectobacterium chrysanthemi (Burkholder et al. 1953, Brenner et al. 1973) and Brenneria paradisiaca to the genus Dickeya gen, nov, as Dickeya chrysanthemi comb. nov. and delineation of four novel species, Dickeya dadantii sp. nov., Dickeya dianthicola sp. nov., Dickeya dieffenbachiae sp. nov. and Dickeya zeae sp. nov. International Journal of Systematic and Evolutionary Microbiology 55:1415–1427.

Schaad NW, Brenner D. 1977. A bacterial wilt and root rot of sweetpotato caused by Erwinia chrysanthemi. Phytopathology 67:302–308.

Seed Health General Publication Published by the Center or CGIAR

Moyer JW, Jackson GVH, Frison EA. (eds.). 1989. FAO/IBPGR Technical Guidelines for the Safe Movement of Sweet Potato Germplasm. Food and Agriculture Organization of the United Nations. Rome/International Board for Plant Genetic Resources, Rome.

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