The performance of dry bean cultivars with and without common bacterial blight resistance in field studies across Canada

Gillard, C. L., Conner, R. L., Howard, R. J., Pauls, K. P., Shaw, L. and Taran, B. 2009. The performance of dry bean cultivars with and without common bacterial blight resistance in field studies across Canada. Can. J. Plant Sci. 89:405-410. Common bacterial blight (CBB) is a serious seed-borne disease in dry beans (Phaseolus vulgaris). Plant breeders have focused on genetic resistance to control this disease, and this led to the release of the first resistant cultivar (OAC Rex) in 2002. In 2003 and 2004, field studies were conducted at six sites across Canada to measure the impact of CBB resistance on dry bean seed yield. Two resistant and four susceptible cultivars were evaluated in noninoculated and inoculated experiments at each site. In the noninoculated experiments, the CBB incidence was very low and there were no treatment differences for measurements of leaf disease. Significant disease pressure occurred in the inoculated experiments at 7 of 12 site-years. Both resistant cultivars usually had less leaf disease than the susceptible cultivars. Yield comparisons between the inoculated and noninoculated experiments were conducted using a yield index calculation to estimate the impact of CBB on the yield of the cultivar. OAC Rex and HR67 had a mean yield advantage of 23.1 and 13.8%, respectively, compared with the mean of the four susceptible cultivars. This is similar to the yield advantage previously reported in the literature.