The individual and interaction of vasicular arbuscular mycorrhiza (VAM), Glomus mosseae and antagonistic biological control agents (BCAs) i. e. Trichoderma harzianum, Penicillium oxalicum and Bacillius subtilis were studied on normal root –rot disease incidence of geranium plants . Application of combined VAM and BCAs reduced root- rot caused by Fusarium solani and Machrophomina phaseolina either in artificial or in natural infested soils compared with individual treatments. VAM was the most effective plant colonization in the presence of BCAs while, biocontrol microorganisms were much higher in soil rhizosphere in mycorrhizal plants over 90 days of plant growth compared with non-mycorrhizae. Furthermore, different biocontrol mat enhanced VAM growth and chitinase production in dual culture. The plants inoculated with combined VAM and BCAs showed increased in chitinase induction in plant roots as well as plant growth, Phosphorous concentration and oil percentage were also increased. The plant which inoculated with G. mosseae showed higher in the presence of either T. harzianum or P. oxalicum. Combined BCAs and VAM had a synergistic effect on disease control.
Key words: Antagonistic biocontrol agents (BCAs), Glomus mosseae , antagonistic microorganism, root –rot disease and Vasicular arbuscular mycorrhizae (VAM).