Races of Puccinia graminis on barley, oat, and wheat in Canada in 2011 and 2012
Fetch, T., Mitchell Fetch, J., Zegeye, T., Xue, A. (2018). Races of Puccinia graminis on barley, oat, and wheat in Canada in 2011 and 2012. Canadian Journal of Plant Pathology, [online] 40(1), 11-21. http://dx.doi.org/10.1080/07060661.2017.1396499
Plain language summary
Stem rust is a devastating disease that has destroyed barley, oat, and wheat crops in Canada. Currently we control stem rust using resistant cultivars. However, new strains (races) of stem rust evolve and can migrate into Canada. Thus, it is necessary to conduct annual surveys to identify the races that are present to ensure Canadian producers are protected from rust epidemics. Surveys were performed in 2011 and 2012 in Saskatchewan, Manitoba, Ontario, and Quebec to determine how much stem rust infection was present and identify the races. Stem rust infection was at very low levels in barley and oat fields and absent in cultivated wheat in 2011 and 2012. For wheat and barley crops, one strain (race QFCSC) was dominant (at 95.6% and 82.8%, respectively) in both years. Other races varied from 2-7% over 2011 and 2012. In oats in 2011, five races (TGN, TJS, TGD, TJJ, and TGB) were dominant (7.6-43.7%) in 2011 whereas three races (TJS, TGN, and TJJ) were dominant (13.9-48.3%) in 2012. While there were no races detected that threaten wheat or barley production, race TJS is a major threat to oat production as it is virulent on all Canadian oat cultivars. Two new races on oat (TNB from Quebec, TQN from Saskatchewan) were detected in 2012, but are not a threat to oat production in Canada.
Stem rust, caused by Puccinia graminis, is a devastating disease attacking barley, oat, and wheat crops globally. The most common control method for stem rust is the use of resistant cultivars. Typically, the identity of deployed resistance genes in a region is known and concomitantly the races they are effective against are also known. Thus, it is critical to identify the virulence dynamics in the pathogen populations to detect new races with virulence to deployed genes. Surveys were performed in 2011 and 2012 in Saskatchewan, Manitoba, Ontario, and Quebec to determine the incidence and severity of stem rust in barley (Hordeum vulgare), oat (Avena sativa), and wheat (Triticum aestivum) fields and to collect infected stem samples to identify the virulence structure in the pathogen populations. Stem rust infection was at trace levels in barley and oat fields and absent in cultivated wheat in 2011 and 2012. Race QFCSC of P. graminis f. sp. tritici was dominant in 2011 and 2012 (95.6% and 82.8% of all samples, respectively). Races QCCJB, QFCJC, and RKQSC were at low (<3%) levels in 2011. In 2012, race RKQSF was at 6.9%, RKQSC at 3.5%, and all others (QFCJC, RTHJF, TMRTF, and TPMKC) at 1.7%. We identified 11 races of P. graminis f. sp. avenae in 2011, with TGN (43.7%), TJS (19.3%), TGD (16.0%), TJJ (7.6%), and TGB (7.6%) being the most frequent. In 2012, 15 races were found and TJS (48.3%), TGN (24.3%), and TJJ (13.9%) were the most frequent. Race TJS is a major threat to oat production as it is virulent on all Canadian oat cultivars. Two new races of P. graminis f. sp. avenae (TNB from Quebec, TQN from Saskatchewan) were detected in 2012, but are avirulent to gene Pg13 and do not threaten oat production in Canada.