Dr. Anfu Hou and Dr. Robert L. Conner, Agriculture and Agri-Food Canada, Morden Research and Development Centre
THE MAJOR FOLIAR diseases of dry bean in Manitoba, and elsewhere in Canada, include common bacterial blight (CBB) and anthracnose. Infection by these diseases can seriously reduce yield and seed quality. Recorded field losses from CBB can be in excess of 36%, and as high as 100% for anthracnose. Seed infection can also result in reduced and uneven germination, affecting seedling vigour when the seed is sown for a subsequent crop. Both diseases are primarily seed-borne, although plant residue can also serve as a source of anthracnose infection. In commercial production, costly seed treatments and chemical sprays usually are used to control the diseases, albeit the practice is often ineffective for CBB. To avoid the seed-borne diseases, ‘clean’ seed often is produced in dry and distant regions such as Idaho and Wyoming, which adds extra costs to the farmers. Development of resistant varieties is considered the most effective and economical approach to manage these foliar diseases. However, based on our screening results in last several years, the most popular dry bean varieties grown in Manitoba are generally susceptible to CBB and anthracnose.
Resistance to CBB does not exist in domesticated dry beans. However, researchers have identified resistance in alien species such as tepary beans. Through various efforts, the resistance genes have been transferred in to the commercial dry bean cultivars, such as OAC Rex developed by the University of Guelph, and the breeding lines HR45 and HR67 developed by Agriculture and Agri-Food Canada (AAFC) Harrow. In a collaborative project with researchers in Manitoba, Ontario and Alberta, the CBB resistance in OAC Rex has been transferred to the early-maturing navy, black and pinto beans in western Canada. In the disease nurseries conducted at Morden, these genetic materials showed improved resistance in comparison to the commercial checks. The presence of these resistance genes has also been confirmed with associated molecular markers. Resistant cultivars such as Portage navy beans in Manitoba, and AAC Black Diamond II in Alberta have been registered in the last few years.
Portage is a high-yielding, early-maturing navy bean cultivar with good seed quality and resistance to common bacterial blight. This variety was developed here in Manitoba at AAFC Morden. Portage is adapted to the dry bean producing regions of southern Manitoba. It has a type II indeterminate upright growth habit suitable for direct harvest, while Envoy has a type I bushy growth habit. P
ortage possesses the major resistance gene transferred from OAC Rex, so it shows much better resistance to CBB than the commercial check (Table 1). In the 2007 and 2008 Manitoba Dry Bean Long Season Wide Row (LSWR) Cooperative Registration Trials over eight site-years, the average yield of Portage was 2589 lb/ac, whereas the yield of Envoy was 2143 lb/ac (Table 1). In the LSWR MPSG Regional Variety Trials conducted at 22 site-years during 2010–2017, Portage yielded 120% of Envoy, maturing, on average, one day later than Envoy (Table 1).
Anthracnose is another important and highly variable disease with a large number of existing races. In western Canada, races 73 and 105 constitute the two primary races present. Breeding cultivars resistant to anthracnose is considered environmentally friendly and the most sustainable long-term solution to control this disease, especially when combined with other management practices.
In a recent screening and molecular marker evaluations, we have identified over forty new germplasm materials that possess various resistant genes. These materials will be very useful in future breeding and genetic studies at Morden.
In 2017, the new cranberry bean cultivar AAC Scotty was registered by AAFC Morden for production in the Red River Valley. It is a high-yielding cultivar with a large seed size and resistance to anthracnose races 73 and 105 (Table 2). In the LSWR Cooperative Registration Trials conducted in 2014 and 2015, the average yield of AAC Scotty was 1429 lb/ac, which was significantly higher than Etna (1138 lb/ac) (Table 2). The average maturity of AAC Scotty is five days later than Etna. In the MPSG LSWR Regional Variety Trials conducted during 2016–2018 (data from Pulse Beat), AAC Scotty yielded 113% of Can09, maturing four days later than the check. AAC Scotty has a type I determinate upright growth habit, with a more scattered pod distribution on the plant, compared to the dense pod distribution to the top of the plant for Etna.
With the ongoing financial support from the Manitoba Pulse & Soybean Growers and the AAFC CAP Pulse Cluster, we will continue the dry bean breeding and pathological research at the Morden Research and Development Centre, for development of improved varieties with a particular focus on disease resistance.
The authors gratefully acknowledge the technical assistance from Mark Sandercock, Larry Dyck, Janet Gruenke, Dena LaBossiere, Nadine Dionne, Waldo C. Penner and Dennis B. Stoesz.
MPSG FUNDING COMMITMENT
Over the last eight years, MPSG has invested $910,444 into dry bean breeding at the Morden Research and Development Centre.