Distribution, pathological and biochemical characterization of Ralstonia solanacearum in Benin

In 2006 and 2007, 75 strains of Ralstonia solanacearum were collected from wilting tomato, pepper and eggplant in Benin. The distribution and the incidence of tomato bacterial wilt in the field were assessed by counting wilted tomato plants on 3 plots of 50 m2 per field. The isolated bacterial strains, including the reference strain, were identified using ELISA, pathogenicity test and carbohydrate oxidation. Bacterial wilt is widely distributed in Benin and was found in five of the eight agro-ecological zones (AEZ) of Benin, which correspond to eight of the 12 districts of Benin. The disease was more severe in ferralitic soil (AEZ V), in valleys and lowlands (AEZ IV) and in highlands (AEZ I). The incidence of tomato bacterial wilt was up to 71%. No R. solanacearum strains were isolated from AEZ II, AEZ VII and AEZ VIII. Strains identified as R. solanacearum were more widely distributed in the south than the center and the north of Benin. Based on biochemical characteristics, Beninese R. solanacearum strains were grouped into biovar I/race1 and biovar III/race 1.