Bacterial wilt, caused by Ralstonia solanacearum (Race 1), is probably the most important bacterial disease of tobacco. The purpose of this study was to identify crops, which aggressively suppress R. solanacearum (Race 1), in their rhizospheres by means of biofumigation. These biologically active crops were then included in crop rotation systems in order to determine their ability to reduce the population of the pathogen below the disease threshold in soils used for tobacco production. When the quantitative assessments of the pathogen population in the rhizospheres were compared, that of marigolds (Tagetes patula) was significantly lower than 70% of plant species evaluated. In vitro - and HPLC tests on marigold root extracts confirmed the inhibitory effect there-of on R. solanacearum, as well as the presence of butenylbithiophene (BBT) and acetoxy butenylbithiophene (BBTOAc), which are two broad-spectrum biocides. A greenhouse trial in 0,5m deep soil indicated that marigolds in combination with non-host winter crops, could reduce the pathogen population of the soil to such an extent that the disease incidence on the follow-up tobacco crop was 60% lower than that of the initial tobacco planting. A four-year rotation trial, on a uniformly and heavily infested field showed that marigolds, in combination with wheat, was responsible for a significantly higher tobacco yield than any other crop combination. In both the greenhouse and field trials, cabbage (Brassica oleracea var capitata) proofed to be a latent host, and should thus be avoided as a winter cash crop in tobacco fields infested with R. solanacearum.