Application of biological control agents for plant diseases can be used as an alternative to synthetic pesticides due to environmental impacts. Recently, rhizobia are employed as biocontrol agents in legumes due to their great advantage of symbiotic N2fixation in legumes as well as to several mechanisms including competition for iron by production of siderophores, competition for nutrients, production of antibiotics and cell wall degrading enzymes or HCN production (Arfaoui et al., 2006).