Studies on efficacy and mode of action of rhizosphere bacteria against Phytophthora spp. in strawberry

After screening of several rhizosphere bacteria against the soilborne pathogens of red core and crown rot disease of strawberry Phytophthora fragariae var. fragariae and Phytophthora cactorum under in vitro conditions, three of the most active isolates such as Raoultella terrigena (G- 584), Bacillus amyloliquefaciens (G-V1) and Pseudomonas fluorescens (2R1-7) were selected for further studies under in vivo conditions. In greenhouse and field experiments, the three isolates were tested against both Phytophthora diseases under artificial infested soil conditions. Root dip treatment with these bacterial antagonists produced a control effect on both fungal diseases up to 55% and were nearly comparable with the chemical fungicide Aliette. First studies on the mode of action of antagonists showed differences in enzymatic reaction.