Understanding the development and management of stripe rust in central Alberta.

Xi, K., Kumar, K., Holtz, M.D., Turkington, T.K., and Chapman, B.P. (2015). "Understanding the development and management of stripe rust in central Alberta.", Canadian Journal of Plant Pathology, 37(1), pp. 21-39. doi : 10.1080/07060661.2014.981215  Access to full text

Abstract

The occurrence of stripe rust (Puccinia striiformis Westend.) of cereal in central Alberta was first documented nearly a century ago. Since the late 1990s, outbreaks of wheat stripe rust caused by P. striiformis f. sp. tritici (Pst) were frequently reported and barley stripe rust caused by P. striiformis f. sp. hordei (Psh) was regularly observed. The major source of stripe rust inoculum for Alberta is considered to be from the Pacific Northwest (PNW) region of the USA. However, this pathogen was found to have the potential to survive on winter wheat in central Alberta and then spread to other winter and spring cereals the following growing season. During 2007–2011, 165 field collections of stripe rust samples were identified to forma specialis and pathotype using wheat and barley differentials. Overlapping virulence was observed in both Pst and Psh isolates that were virulent on highly susceptible wheat and barley cultivars and lines. Potential hybridization between the two formae speciales is considered to be the source of isolates capable of overcoming multiple wheat and barley resistance genes. The predominant Pst races were similar between central Alberta and the PNW, while the predominant Psh races appeared to be different between the two regions. Wheat genes in differential lines were found to show more resistance in central Alberta trap nurseries than in southern Alberta and the PNW. Low to moderate disease pressure in central Alberta was sufficient to cause significant yield losses in susceptible spring wheat cultivars, while there was limited to no yield reduction in resistant or intermediate cultivars in this region. Winter wheat is generally more susceptible than spring wheat and, thus, yield losses in winter wheat are more likely to occur than susceptible spring wheat in this region. Considerably more two-row hulled barley lines were resistant than six-row and hulless lines screened in international nurseries. For management of this disease, an integrated approach is discussed in relation to central Alberta conditions.

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