Virulence Dynamics and Breeding for Resistance to Stripe, Stem, and Leaf Rust in Canada Since 2000

Wheat (Triticum spp.) is a major field crop in Canada in terms of acreage, annual production, and export market value. There are nine classes of Canadian wheat based on growth habit (winter or spring), kernel hardness (hard or soft), seed coat color (red or white), and quality factors (grain protein content and gluten strength). Wheat was described by Newman in 1928 as "the economic fairy to the industrial and commercial life of Canada, having built practically the whole economic structure of the Prairie Provinces." Wheat production in Canada is affected by several biotic and abiotic stresses. The major abiotic stresses are frost damage, drought, and heat stress. Among biotic stresses, diseases caused by fungal pathogens are the most important although wheat streak mosaic virus (WSMV) has caused some localized outbreaks in some years. In context of cultivar registration in Canada, there are certain diseases that breeders have to take into account while developing resistant cultivars. The Prairie Recommending Committee for Wheat, Rye, and Triticale (PRCWRT) classify wheat diseases into priority one, priority two, and priority three depending on prevalence and potential damage they can cause. However, priority one diseases are more of a concern and a minimum level of resistance in commercial cultivars is recommended for those.