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June 27, 2004
From: European and Mediterranean Plant Protection Organisation (EPPO) Reporting Service 2004, No. 01 [edited]


2004/003 1st report of _Clavibacter michiganensis_ subsp. _sepedonicus_ in Slovakia

The Slovakian National Plant Protection Organisation (NPPO) recently reported the first findings of _Clavibacter michiganensis_ subsp. _sepedonicus_ [Cms] (EPPO A2 list) on plants of _Solanum tuberosum_ in its territory. All necessary measures have been taken to prevent the spread of, and to eradicate, the bacterium.

The findings involved the cadastral territory of Svodov (district of Levice) and Trstene pri Hornade (district of Kosicevidiek). The finding in Svodov was confirmed by IF, PCR, and RFLP testing. In Trstene pri Hornade, Cms was confirmed by immunofluorescence, polymerase chain reaction, restriction fragment length polymorphism, and bioassay, and was also retested by IF and plating on growing media.

The source of the infection is currently being investigated, and it is assumed that the original potato seeds (cvs. Velox and Solara) were imported from EU member states.

The situation involving Cms in Slovakia can be described as follows: 1st reported in 2004 in 2 localities in the districts of Levice and Kosice-vidiek, it is under eradication measures.

Source: NPPO of Slovakia, 2004-01

[Contrary to the title of this piece, this report appears to be the second instance of Cms infection in potato in Slovakia, the first being reported in 2002. Ring rot is a very destructive disease, which adversely affects tuber quality. The disease is especially damaging to seed producers since disease-free seed is the foundation of any seed potato production program. Disease management depends upon zero tolerance of the pathogen and
application of very strict phytosanitary measures to maintain freedom from contamination. Quaternary ammonia, bleach, chlorine dioxide, iodine, and phenol groups are useful disinfectants.

Cms can remain latent in tubers, so adequate laboratory testing of seed lots is required. Damage is caused by destruction of vascular tissues and subsequent wilting and dying of plants and secondary rotting of tubers. Crop losses have been mainly reported from North America (up to 50 per cent) and from Russia (15 to 30 per cent of plants infected, up to 47 per cent crop loss). Where ring rot occurs in the EPPO region, the disease appears more sporadically and at low levels of infection. The low disease occurrence in this area is due to the fact that cutting of potato seed, and use of pricker-type planters, is uncommon in Europe. When tubers are cut, however, higher levels may also occur (up to 30 per cent crop loss in France). Economic losses are due to wilt and tuber rotting in the field and in storage. Indirectly, expenses related to the disinfection of sacks, machinery, stores etc., prohibition of potato cultivation, and restriction, or prohibition, of export trade may increase economic loss.

Useful references:
<http://www.researchinformation.co.uk/pest/sample/15-1/09-stead.pdf>
<http://www3.sk.sympatico.ca/sspga/disease.htm>
<http://www.eppo.org/QUARANTINE/bacteria/Clavibacter_m_sepedonicus/CORBSE_ds.pdf> 
- Mod.DH]