Gaudet, D. A., Puchalski, B. J., Despins, T., McCartney, C., Menzies, J. G. and Graf, R. J. 2013. Seeding date and location affect winter wheat infection by common bunt (Tilletia tritici and T. laevis) in western Canada. Can. J. Plant Sci. 93: 483–489. The majority of western Canadian winter wheat varieties are susceptible to common bunt (Tilletia tritici and T. laevis) and the risk to production, particularly in Saskatchewan and Manitoba, where the majority of production occurs, is unknown. Inoculated trials were employed to determine the effects of fall seeding date on bunt infection levels on one resistant and two susceptible winter wheat varieties at three locations in western Canada during three growing seasons from 2007/2008 to 2009/2010. Among the three locations, average infection levels were highest in Lethbridge, AB, followed by Glenlea, MB, and Saskatoon, SK. Later seeding resulted in high infection levels at all three locations in the susceptible varieties, particularly in Lethbridge, but high infection levels were observed in the earliest seeded treatments at both the Saskatchewan and Manitoba locations. The resistant variety Blizzard consistently exhibited infection levels of less than 3% infection across all environments. In a second test at conducted at Lethbridge, 10 of the 11 currently grown winter wheat varieties were susceptible to common bunt. These results indicate that there is a general risk of common bunt infection to winter wheat production across western Canada and that control measures must be taken until resistant varieties are developed.