Ralstonia solanacearum (race 1) detected in Rosa in the Netherlands
In September 2015, Ralstonia solanacearum (EPPO A2 List) was detected in the Netherlands at a glasshouse company producing Rosa cut flowers (cv. ‘Armando’), located in the municipality of Westland. Unusual symptoms had been noticed by the grower. Black discoloration and necrosis of stems, as well as chlorotic and wilting leaves were observed on several plants. In this glasshouse of 1.6 ha, it is estimated that 0.3 ha was affected by the disease. In 2015-10-09, a second glasshouse company producing Rosa cut flowers and located in the municipality of Waddinxveen was found to be infected. R. solanacearum was detected in several lots of the varieties ‘Savita’ and ‘Talea’/’Aventique’ (mixed sample). In this glasshouse of 4 ha, it is estimated that 2 ha were affected by the disease: 0.5 ha of cv. ‘Savita’ and 1.5 ha of cvs. ‘Talea’ and/or ’Avantique’. Further investigations are under way to determine whether one or both cultivars are infected. Finally in 2015-10-23, a third glasshouse company located in Almere was found to be infected. In this company of 20 ha of Rosa cut flower production, 5 ha of ‘cv. ‘Red Naomi’ were found to be infected.
In the 3 companies concerned, all infected lots have been destroyed. Cut flower lots which tested negative for R. solanacearum were allowed to be traded. Tracing-back and tracing-forward studies are being carried out at companies which are producing cut flowers and propagating material of Rosa. These studies include testing of plant material and water used within the glasshouses. The origin of the outbreaks on Rosa remains unknown. In order to explore possible links with earlier findings of R. solanacearum (race 1) on plants for planting of Anthurium (see EPPO RS 2015/164) and Cucurma (see EPPO RS 2014/192), a comparative DNA analysis was performed on isolates from Rosa, Anthurium and Curcuma. The first results revealed no differences among Rosa isolates but showed that Rosa isolates differed from Anthurium and Curcuma isolates. Finally, the NPPO declared that a specific surveillance programme carried out in companies producing Curcuma has confirmed the successful eradication of the bacterium from this crop.
The pest status of Ralstonia solanacearum (race 1) in the Netherlands is officially declared as: Transient: actionable, found on Anthurium plants for planting and Rosa for cut flower production, under eradication.
Sources
NPPO of the Netherlands (2015-09 and 2015-10).