Races of Puccinia graminis on barley, oat, and wheat in Canada in 2013 and 2014

Citation

Fetch, T., Mitchell Fetch, J., Zegeye, T., Xue, A. (2021). Races of Puccinia graminis on barley, oat, and wheat in Canada in 2013 and 2014. Canadian Journal of Plant Pathology, [online] 43(1), 101-107. http://dx.doi.org/10.1080/07060661.2020.1745892

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 research to identify the races that are present in Canada to ensure Canadian producers are protected from rust epidemics. Collections were made in 2013 and 2014 in Manitoba, Ontario, Quebec, and Saskatchewan 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 2013 and 2014. For wheat and barley crops, one strain (race QFCSC) was dominant (at 86% and 100%, respectively) in both years. This race does not present a danger to Canadian producers. Other races varied from 2-5% in 2013. In oat collections race TJS was dominant (at 57% and 75%, respectively) in both years. Race TJJ was the next most common race in both years, at 24% and 19%. Both oat races are a major threat to oat production because they are virulent on all Canadian oat cultivars. We need to find new rust resistance genes to protect oat crops from stem rust infection.

Abstract

Stem rust, caused by Puccinia graminis, is a catastrophic disease that has and continues to cause yield losses in barley, oat, and wheat crops worldwide. Use of host resistance genes is the most economic, efficient, and environmentally best method to control the disease. Resistance genes have been incorporated into most commercial cultivars and have been effective, for races in the North American populations of P. graminis. However, new races of stem rust are constantly emerging and therefore it is imperative to monitor the virulence structure in the populations to detect new races with increased virulence. Stem rust samples were collected in 2013 and 2014 in Manitoba, Ontario, Quebec, and Saskatchewan to determine the incidence and severity of stem rust in barley (Hordeum vulgare), oat (Avena sativa), and wheat (Triticum aestivum) fields and to characterize the virulence dynamics in the pathogen populations. No stem rust was found in cultivated wheat, and incidence was at trace (<1%) levels in barley fields and very low (0–5%) levels in oat fields in 2013 and 2014. In wheat trap plots and collections from barley, race QFCSC of P. graminis f. sp. tritici was dominant in 2013 (85.9%) and was the only race found in 2014. Races MCCFC, QTHJF, RFCSC, RKQSC, and TMRTF were at low (<5%) levels in 2013. From collections in oat fields and stands of wild barley, nine races of P. graminis f. sp. avenae were found in 2013, with TJS (56.9%) and TJJ (23.5%) the most frequent. In 2014, we found only six races and TJS (74.5%) and TJJ (19.1%) were the most frequent. No new races of stem rust were detected in Canada in 2013 or 2014.