Potentiality of Binucleate Rhizoctonia Isolates as Root Rot Causing Pathogens on Faba Bean

Abstract

the present study was conducted to identify and determine the pathogenic capabilities of 78 binucleate Rhizoctonia isolates isolated from faba bean plants showing root rot and stem canker symptoms. Identification, depending on morphological features, has proved that isolates represented as: two isolates Rhizoctonia calle, 26 isolates R. fumigata, 48 isolates R. cerealis and two species are still unidentified due to edict of identification key. In vitro pathogenicity test was achieved for all binucleate isolates comparing with one accurate identified polynucleate Rhizoctonia solani (AG4-HGI). All isolates were found to be pathogenic and most of them showed the same degree of pathogenicity as R. solani. Potentiality of the most aggressive 4 isolates (belonging to R. cerealis) on faba bean as the causal of root rot was assessed comparing with polynucleate R. solani on disease incidence and on plant growth characters under greenhouse conditions. Binucleate tested isolates showed significantly greater disease incidence, and showed significant depressed effect on both shoots and roots compared with control. Results indicated the importance of binucleate Rhizoctonia spp. as causal agents of faba bean root rot.