RESUMO
Objective: To isolate the pathogenic Ralstonia solanacearum from the infected Pogostemon cablin plants and to study the bacteria characteristics, so as to lay a foundation for the control of bacterial wilt. Methods: Pathogenic strains of R. solanacearum were isolated from the infected P. cablin plants by being streaked on a tetrazolium chloride (TZC) medium. These strains were used for the classification based on oxidative utilization of three kinds of disaccharide (lactose, maltose, and cellobiose) and three kinds of hexy I alcohol (mannitol, dulcitol, and sorbitol). The pathogenicity was tested by the methods of cutting and soaking roots. Results: Seven strains of pathogenic R. solanacearum were isolated from the infected P. cablin plants which contain four biotypes. Strains of HX5 and HX7 belong to biotype I, HX1 and HX6 belong to biotype II, HX2 and HX4 belong to biotype III, and HX3 belongs to biotype V. The result of pathogenicity test indicated that the most strains had strong pathogenicity. HX4 and HX5 have more serious virulence and can cause higher plant death rate. Conclusion: Strains of R. solanacearum with different biotypes from the P. cablin plants have different pathogenicity.