Evaluation of Root Rot Resistance in Dry Bean Cultivars

Root rot causes serious reductions in plant stand and yield in dry beans. Recent field surveys have shown that bean root rot is caused by a complex of pathogens that includes as many as seven fungal species. Resistance is not a common trait in most of the bean cultivars grown in Manitoba, but a few dry bean cultivars have been shown to have partial resistance to the root pathogens Rhizoctonia solani, Fusarium redolens, F. acuminatum and F. solani. This research involves the separate evaluation of bean cultivars for their reactions against isolates of Rhizoctonia solani, Fusarium redolens, F. solani, F. avenaceum, F. oxysporum and the newly discovered bean root rot pathogen F. cuneirostrum. A total of 68 cultivars from all the dry bean classes grown in Manitoba were assessed for their reactions to the six root pathogens in separate, replicated field trials at AAFC-Morden and AAFC-Brandon (Dr. D.L. McLaren) in 2015. For each root pathogen, significant differences in seedling emergence, root rot severity and root nodulation were observed among the dry bean cultivars at both locations. Information from this study will be provided to bean breeders to choose root rot resistant parents for their crossing programs and will aid bean producers in making informed decisions in the selection of dry bean cultivars for their field operations.