Researchers are continuing to monitor plots and a few fields for stripe rust survival throughout the winter and early spring.
“Evidence of overwintering stripe rust was reported by Drs. Kequan Xi and Krishan Kumar in 2013-2014 in central Alberta,” says Michael Harding, research scientist-plant pathology, Alberta Agriculture and Rural Development, Brooks. “This winter, Dr. Denis Gaudet has extended his stripe rust survey to include some winter evaluations in Southern Alberta.”
Dr. Gaudet reported that eight winter wheat fields in the southwestern region (Lethbridge, Cardston, Raymond and Coaldale) of southern Alberta were surveyed on December 12, 2014.
“Stripe rust levels of five percent were observed in two fields and trace levels in a third field, says Harding. “Stripe rust was widespread in volunteer winter and spring wheat throughout the region. It was apparent that stripe rust had infected winter wheat that was seeded from early to late September (ie Zadoks stage 21) but later seeded winter wheat (Zadoks stage 1) remains clean. Stripe rust was also wide spread in winter wheat research plots.”
Dr. Kequan Xi had also noticed the effect of seeding date on stripe rust infections of winter wheat. Dr. Xi noted that his limited survey results from central AB showed that the degree of stripe rust severity or prevalence appeared to be more associated with seeding time of winter wheat than cultivar resistance ratings during fall surveys (at the seedling stage). More specifically, an early seeded field (i.e before early September) tended to have more stripe rust than late seeding (i.e. after early September) regardless of genetic resistance ratings of each cultivar. The early seeding effect observed by both researchers is likely due to the fact that stripe rust spores were in the air in early September, but not later in the month. Therefore leaves of the later seeded plants escaped disease because they had not yet emerged and could not be infected. The difference in severity between resistant and susceptible cultivars becomes apparent later, in early spring.
Dr. Gaudet indicated that his group would be monitoring plots and a few fields for stripe rust survival throughout the winter and early spring. He also noted that the presence of stripe rust in the three winter wheat fields in southern Alberta does not necessarily mean that the stripe rust pathogen will be able to survive overwinter in those fields. If any overwintering survival of the stripe rust pathogen occurs, it cannot be detected until spring 2015.
Contact:
Michael Harding
403-362-1338
Alberta Agriculture and Rural Development