First report of Ralstonia solanacearum on potatoes in Poland
The NPPO of Poland recently informed the EPPO Secretariat of the first report* of Ralstonia solanacearum (EPPO A2 List) on ware potatoes (Solanum tuberosum) on its territory. In December 2014, R. solanacearum was detected during an official survey which was carried out in a place of production already under quarantine because of the earlier detection of another bacterium (Clavibacter michiganensis subsp. sepedonicus). R. solanacearum was found in 1 lot (48 tonnes) of ware potatoes (S. tuberosum cv. ‘Lady Claire’) from a field (1.5 ha) located in the Opolskie voivodeship (southwestern Poland). Tuber samples were collected and tested (IF, PCR, RFLP, bioassays). As this was the first finding of R. solanacearum in potatoes in Poland, the positive results obtained were confirmed by Fera in York (GB). The NPPO proposed the following reasons which might explain this infection:
1) The certified seed potatoes used in 2014 to produce the infected ware potatoes (cv. ‘Lady Claire’) had been produced in 2013 from seed potatoes originating from another EU Member State. In 2013, within the seed potato harvest produced from the above lot, 2 samples were found to be positive for R. solanacearum after an IF screening test but this suspicion was not confirmed by further testing (IF, FISH, PCR-RFLP).
2) In 2014, at the place of production where R. solanacearum was found in cv. ‘Lady Claire’, additional samples were taken from other potato lots. Among them, 2 samples (cv. ‘Taurus’) were found to be positive for R. solanacearum after an IF screening test but this suspicion was not confirmed by further testing (IF, FISH).
The pest status of Ralstonia solanacearum in Poland is officially declared as: Present, under eradication.
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* EPPO note: this is the first time that R. solanacearum is found on potatoes. The bacterium had previously been detected once in a water sample in 2011 (see EPPO RS 2011/242).
Sources
NPPO of Poland (2014-12).