Urtica dioica is a weed host of Ralstonia solanacearum
In the Netherlands, the NPPO has done extensive surveys on the presence of Ralstonia solanacearum (EPPO A2 quarantine pest) in surface water, as well as studies on possible infection of weeds in natural conditions. The population dynamics of the bacterium in surface water were monitored in two selected areas, over a 2-year period. In some cases during summer, high bacterial number (up to 106 cfu l-1) were observed. Populations decreased during winter. Several weeds were studied: Bidens frondosa, Lycopus europaeus, Mentha aquatica, Solananum dulcamara (already considered as a host), and Urtica dioica (stinging nettle). During this study, it was found that U. dioica could be a natural host of R. solanacearum when plants were growing with their roots in contaminated water. The bacterium can live and systemically infect U. dioica roots. During glasshouse experiments, it was shown that R. solanacearum is pathogenic to U. dioica and S. dulcamara under high infection pressure and high temperature. This is the first report of U. dioica being a potential natural weed host of R. solanacearum. The implications of this finding on the epidemiology of the disease need to be further studied.
Sources
Wenneker, M.; Verdel, M.S.W.; Groeneveld, R.M.V.; Kempenaar, C.; van Beuningen, A.R.; Janse, J.D. (1999) Ralstonia (Pseudomonas) solanacearum race 3 (biovar 2) in surface water and natural weed hosts: First report on stinging nettle (Urtica dioica).
European Journal of Plant Pathology, 105(3), 307-315.