Testing for resistance to smut diseases of barley, oats and wheat in western Canada

The smut pathogens of barley (Hordeum vulgare), oat (Avena sativa), and wheat (Triticum aestivum) were likely introduced to Canada on seed of their hosts by pioneering farmers. In the late 19th and early 20th centuries, smut diseases were common and often severe in western Canada. These diseases have become effectively controlled through the use of certified seed, seed treatment fungicides, and resistant cultivars. Genetic resistance is inherent in the cultivar and is often preferred over other control techniques because it avoids the costs, environmental concerns, and health risks that can be associated with seed-treatment chemicals. Resistance to smut diseases of barley, oat, and wheat are criteria used in the evaluation of new lines for registration for commercial production in western Canada. This article provides a brief introduction to the taxonomy of smut pathogens of small grain cereals and the methods used for determining pathogenic variability within the pathogen population. We also describe the techniques used for inoculating and assessing candidate cultivar lines for smut resistance in western Canada. These techniques are not difficult, and large numbers of lines can be tested each year; however, they are labour, time, and physical-resource intensive. The integration of plant pathology and breeding and the role of the Canadian regulatory system as they relate to varietal resistance to the smut fungi are considered.