Biology Many species of rust affect barley, oats, rye, triticale, wheat and grasses. Each rust species includes a number of strains that differ only in their ability to infect certain host crop varieties. Both stem and leaf rust require two different unrelated host species to complete their life cycle.
Stripe rust has no known alternate host.
Because the alternate hosts for stem and leaf rust are not found in Alberta, infectious spores must be blown in from rust-infected crops in the United States. These rust spores directly infect susceptible cereal crops. A single spore pustule on a cereal leaf or stem may produce millions of infectious spores, which can infect other susceptible cereals. The stripe rust fungus occasionally overwinter in Alberta as the infectious brown spore stage on susceptible winter wheats such as Norstar. Infectious brown spores from infected winter wheat are able to infect susceptible varieties of soft white wheat earlier in the season, causing considerable damage.