Antifungal activity of secondary metabolites of Pseudomonas fluorescens isolates as a biocontrol agent of chocolate spot disease (Botrytis fabae) of faba bean in Ethiopia

Pseudomonas fluorescens isolates possess a variety of promising properties of antifungal activity of secondary metabolites which make it as a biocontrol agent. In the present study, 12 isolates of P. fluorescens were isolated from rhizospheric soil of faba bean crop evaluated for their antagonistic activity against chocolate spot disease (Botrytis fabae) of faba bean. P. fluorescens 10 (Pf 10) (88.1%) showed high antagonistic activity against B. fabae. All isolate of P. fluorescens were successfully employed in controlling chocolate spot disease of faba bean due to their antifungal metabolites. The antifungal compounds were extracted from all P. fluorescens isolates with equal volume of ethyl acetate, hexane and methanol. The antifungal compounds extracted with ethyl acetate, hexane and methanol from P. fluorescens 3 (Pf 3), P. fluorescens 8 (Pf 8), and P. fluorescens 3 (Pf 3), isolates at 0.1% concentration completely inhibited the mycelial growth of the pathogen respectively. Bio-primed faba bean seeds with isolates of P. fluorescens 9 (Pf 9) and P. fluorescens 10 (Pf 10) evaluated against B. fabae in vivo (pot culture) indicated the inhibitory effects to the pathogen and also showed the inducing properties to enhance the immune system of crop. Therefore, it can be concluded that the use of P. fluorescens 9 (Pf 9) and P. fluorescens 10 (Pf 10) of isolates could inhibit the mycelial growth and reduced the disease incidence, severity and infection processes of B. fabae and simultaneously increase the plant growth performance and yield of faba bean. These isolates can be used as potential biocontrol agents against B. fabae and also used as biofertilizers for the production of faba bean.   Key words: Antifungal, Biocontrol, Botrytis fabae, Faba bean, Pseudomonas fluorescens.