Black root rot disease (Fusarium solani) is considered as a major problem in faba bean crops causing great losses in seed yield and low productivity. A randomized complete block design with nine treatments and three replications were employed at Ambo Plant Protection Research Center (APPRC) and Holetta Agricultural Research Center fields. The analysis of variance revealed that highly significant (P ≤ 0.001) variation among the herbicides and Rhizobium strains treatments for grain yield, thousand seeds weight and Black root rot disease incidence and severity on faba bean. Thus, higher grain yields of 2.26 and 3.64t ha-1were recorded from plots treated with Rhizobium strain FB1035. However, plots treated with herbicides plus Rhizobium strains gave lower yield than plots treated with Rhizobium strain alone. Plots treated with Rhizobium strain FB1035 showed less disease incidence (34.943 and 13.6767%) and severity (25.377 and 14.391%) respectively. However,the highest disease incidence (61.77 and 29.026 %) and severity (66.23 and 32.687 %) were recorded from the control plot. The disease severity was found negatively correlated with yield and yield components at both locations. Considering economic benefits, Partial budget analysis revealed that the highest total gross yield benefit (birr 35030 ha-1 and birr 56420ha-1) were obtained from plots treated with Rhizobium strain FB1035, proving that the application of Rhizobium strains alone were profitable.Thus, it is recommended to use these Rhizobium strains for the best protection against faba bean black root rot and improve the productivity of faba bean.
