First report of Ralstonia solanacearum on roses in Switzerland
The NPPO of Switzerland recently informed the EPPO Secretariat of the first record of Ralstonia solanacearum (EPPO A2 List) on its territory. In December 2016, the presence of R. solanacearum (race 1) was confirmed in 2 sites of cut flower production of roses (Rosa spp.) in the cantons of Bern and Solothurn. The bacterium was identified in several varieties of Rosa plants (Dali, Savannah, Alpe d’Huez, Hypnotic, and SR 75965) grown in greenhouses. This finding results from tracing forward investigations triggered by the fact that the Dutch NPPO had provided the Swiss NPPO with a list of potentially infected lots of Rosa plants. These plants had been delivered by Dutch propagation companies between June 2015 and August 2016. Several inspections of these suspicious Rosa plants and other potential host plants took place between mid-November and mid-December 2016. Plants were visually inspected but none displayed typical symptoms of R. solanacearum. Samples were collected from plants (stems), as well as from irrigation water, and were taken to the laboratory for analysis (PCR, sequencing, isolation on selective media, pathogenicity tests are also under way). The bacterium was not detected in irrigation water but, as explained above, it was found in 2 production sites. The number of infected plants and the size of the area affected are still under investigation, and intensive testing of symptomless plants is currently being carried out. In particular, the situation of 3 other companies which had also received suspicious lots is still under investigation. Eradication measures will be taken and surveys will continue until eradication is achieved. All plants belonging to lots which have been found to be infected by R. solanacearum will be destroyed and strict hygiene measures will be taken in the greenhouses concerned.
The pest status of Ralstonia solanacearum in Switzerland is officially declared as: Transient, actionable, under eradication.
Sources
NPPO of Switzerland (2017-03).