Soybean [Glycine max (L.) Merr.] production in short‐season areas has increased greatly because of improvements in cultivars and production practices. Previous studies of genetic improvement in soybean have reported yield increases of 0.5 to 1% per year. To evaluate the genetic improvement of short‐season germplasm, 41 cultivars ranging from maturity group 000 to 0, released from 1934 to 1992, were grown for 8 station‐years in Ontario and Quebec. Yield, maturity, plant height, lodging score, 100‐seed weight, seed protein and oil levels, and yield stability were regressed on year of release to determine if improvements have been made. Yield has been improved about 0.5% per year during the period under study; however, since 1976 yield has been improved about 0.7% per year. There is evidence that the rate of genetic improvement of seed yield is accelerating. Significant lodging reduction was also observed. Seed protein levels have been reduced 4 g kg‐1 yr‐1 and seed oil levels have increased 4 g kg‐1 yr‐1. Although yield has been increased, yield stability has remained constant.

Weed management options for adzuki-bean growers in Ontario, Canada are limited due to few herbicide registrations. Four field trials were conducted at three locations in south-western Ontario in 2007 and 2008 to determine the tolerance of adzuki bean to several preplantincorporated (PPI), pre-emergence (PRE), and post-emergence (POST) herbicides. All the herbicides were applied at the doses registered for use in soybean. The application of pendimethalin, cloransulam-methyl, and halosulfuron-methyl (PPI), flumetsulam, cloransulammethyl, and halosulfuron-methyl (PRE), and acifluorfen and fomesafen (POST) caused Յ15% crop injury; however, the injury was transient and did not reduce the adzuki bean yield. The POST application of cloransulam-methyl and imazethapyr caused Յ23% crop injury and reduced the biomass by Յ50%, but did not reduce the plant height or crop yield. Metribuzin, flumetsulam, atrazine, and pyroxasulfone (PPI), metribuzin, linuron, pyroxasulfone, and atrazine (PRE), and bentazon, imazethapyr plus bentazon, halosulfuron-methyl, and thifensulfuronmethyl (POST) caused Յ61% crop injury.These treatments reduced the biomass, plant height, and crop yield. Based on these results, pendimethalin, cloransulam-methyl, and halosulfuronmethyl applied PPI, flumetsulam, cloransulam-methyl, and halosulfuron-methyl applied PRE, and acifluorfen and fomesafen applied POST might be potential weed management options for weed management in adzuki bean. Cloransulam-methyl and imazethapyr applied POST will need further evaluation due to phytotoxicity concerns. Metribuzin, flumetsulam, atrazine, and pyroxasulfone applied PPI, metribuzin, linuron, atrazine, and pyroxasulfone applied PRE, and bentazon, imazethapyr plus bentazon, halosulfuron-methyl, and thifensulfuron-methyl applied POST did not have an adequate margin of safety.

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To facilitate early diagnosis and improve control of bean anthracnose, a rapid, specific, and sensitive polymerase chain reaction (PCR)-based method was developed to detect the causal agent, Colletotrichum lindemuthianum, in bean (Phaseolus vulgaris) seed. Based on sequence data of the rDNA region consisting of the 5.8S gene and internal transcribed spacers (ITS) 1 and 2 of four C. lindemuthianum races and 17 Colletotrichum species downloaded from GenBank, five forward primers were designed and evaluated for their specificity. Among them, one forward primer was selected for use in combination with ITS4 to specifically detect C. lindemuthianum. A 461-bp specific band was amplified from the genomic DNA template of 16 representative isolates of C. lindemuthianum, but not from 58 representative isolates of 17 other Colletotrichum species or 10 bean pathogens. Moreover, to enhance the sensitivity of detection, nested PCR was applied, which allowed the detection of as little as 10 fg of C. lindemuthianum genomic DNA and 1% infected seed powder, which was mixed with 99% healthy seed powder. The diagnostic analysis can be completed within 24 h, compared with about 2 weeks required for culturing. Furthermore, this method can be performed and interpreted by personnel with no specialized taxonomic expertise.

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. Key words: Dry bean, Phaseolus vulgaris, Xanthomonas axonopodis pv. phaseoli, resistance, yield