The Epidemiology and Management of Ralstonia solanacearum and Ralstonia pseudosolanacearum in Central and Northern Europe

The brown rot of potato and bacterial wilt in solanaceous plants are caused by Ralstonia solanacearum, one of the most important plant pathogens in the world, which is present in multiple locations globally, capable of infecting hundreds of plant species and resulting in severe economic losses. This soilborne bacterium enters the roots of the plant and proliferates in the xylem, causing the characteristic wilting symptoms. It is taxonomically grouped into the Ralstonia solanacearum species complex (RSSC), formed by R. solanacearum, R. pseudosolanacearum and R. syzygii. In Central and Northern Europe, potato brown rot has been historically caused by cool-adapted R. solanacearum strains since the 1970s. However, a 2015 outbreak in the Netherlands of warm-adapted R. pseudosolanacearum in greenhouse Rosa spp. has highlighted the risk of potential geographical and host range expansion of tropical RSSC species. Continuous surveillance of host plants and surface waters using reliable identification tests needs to be maintained to prevent new outbreaks. Until now, no method has been able to efficiently limit the spread of RSSC species, or to eradicate the bacterium in the field. Biological control methods, including the use of antagonistic bacteria or bacteriophages, have however shown great promise, potentially providing an environmentally friendly approach to control this pathogen.