Antagonistic Effect of Native Bacillus Isolates against Black Root Rot of Faba Bean
Faba bean (Vicia faba L.) is one of the most important pulse crops grown in eastern Africa. Black root rot (Fusarium solani) is known to cause great yield losses in faba bean, especially in the highlands of Ethiopia. The objective of this study was to evaluate the biological control ability of native Bacillus species on the basis of their antagonistic effects against F. solani. The study was conducted in vitro and in a greenhouse. All tested Bacillus isolates significantly (P<0.05) reduced radial mycelial growth of the pathogen. Seven bacterial isolates restricted growth of the pathogen to <14 mm diameter, and showed 39-44% efficacy over the positive control. Isolate BP048 was the most effective, with 43.6% efficacy. The lowest inhibitory effects, 15.5 and 27.8%, were recorded from isolates BS083 and BS0102, respectively. The culture filtrate of the bacterial isolates also inhibited F. solani spore germination. In vivo, the isolates significantly reduced severity of black root rot on artificially inoculated faba bean seedlings. The antagonist Bacillus isolates kept black root rot severity low with more than 50% disease suppression, compared to the untreated control.
Keywords: Ethiopia, Fusarium solani, Vicia fabae