Department of Plant Sciences

The fungus Fusarium oxysporum Schlecht f. sp. radicis-lycopersici Jarvis and Shoemaker (FORL) causes crown and root rot in tomato (Lycopersicon esculentum Mill.), which is a serious problem for field and greenhouse production causing significant losses. The main objective of this study was to test the efficacy of two commercial bacteria strains Pseudomonas sp. ”Proradix” (DSMZ 13134) (Proradix®, Sourcon Padena, Tübingen-Germany) and Bacillus amyloliquefaciens FZB42 (RhizoVital® 42 TB, ABiTEP, Berlin, Germany) in improving mycorrhization, nutrient status and plant growth of tomato affected by FORL. Soil inoculation with P. sp. ”Proradix” and B. amyloliquefaciens FZB42 in single and combined application significantly improved root and shoot biomass production of tomato, and P, Mn and Zn shoot concentrations in pathogen-infested soil. After application of the bacteria strains, roots of tomato were healthier and showed a significantly higher colonization by arbuscular mycorrhizal fungi if the latter was inoculated too. Combined inoculationd with the bacteria strains and arbuscular mycorrhizal fungi increased the observed effects on dry matter and shoot nutrient concentrations. However, clear synergistic effects could not be detected. The results obtained suggest an important role of rhizosphere interactions for the expression of bio-control mechanisms by inoculation with effective Pseudomonas and Bacillus strains in addition to simple antagonistic effects.