Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/13/2001
Publication Date: 3/1/2001
Citation: KOLMER, J.A. PHYSIOLOGIC SPECIALIZATION OF PUCCINIA TRITICINA IN CANADA IN 1998. PLANT DISEASE. 2001. v. 85. p. 155-158. Interpretive Summary: Leaf rust is a disease of wheat that is caused by a fungus called Puccinia triticina.Leaf rust can commonly cause yield losses of 5-10% in wheat. The fungus produces dry spores on the wheat plants which are carried by wind across North America wherever wheat is grown. There are different types of the leaf rust disease fungus which are called physiologic races. Different traces of leaf rust can be found in different parts of North America. The races of leaf rust differ in their ability to attack wheat cultivars that often differ for genes that give resistance to leaf rust. An annual survey of the leaf rust races is conducted in Canada. Results of the leaf rust survey are used to track how the leaf rust races change over time in the different geographical regions of Canada. In 1998 34 different races of Puccinia triticina were identified in Canada. The races in the eastern part of Canada (Ontario and Quebec) were different compared to the races in nManitoba and Saskatchewan. Certain wheat cultivars in Manitoba suffered more yield loss to leaf rust because of an increase in the races of leaf rust that could attack these wheat cultivars. The results of this study are important because they show the extent of different races of wheat leaf rust in different parts of Canada, and the information can be used to help wheat breeders develop wheat lines with improved resistance to leaf rust.
Technical Abstract: In 1998, leaf rust of wheat (Triticum aestivum), caused by Puccinia triticina, was widespread throughout the prairies of western Canada. Warm summer temperatures with frequent dew periods favored spread of the disease in wheat fields in Manitoba and Saskatchewan. The Canada Prairie Spring wheat cultivars (AC Vista, AC Foremost, AC Crystal) were susceptible to leaf rust, while the bread wheat cultivars with leaf rust resistance genes Lr16 and Lr13 or Lr34 (AC Majestic, AC Domain, AC Barrie) had high to moderate levels of leaf rust infections. Bread wheat cultivars AC Cora, AC Minto, Pasqua, and McKenzie had trace to low levels of leaf rust infection. Thirty four virulence phenotypes of P. triticina were identified on 16 Thatcher lines which are near-isogenic for leaf rust resistance genes. Phenotypes with virulence to Lr16 increased to 25% of isolates in Manitoba and Saskatchewan in 1998. Forty-three isolates were also tested for virulence to plants with the adult plant resistance genes Lr12, Lr13, Lr34 and Lr13,34. Most isolates had virulence to Lr12, and Lr13. All isolates had lower infection type on adult plants with Lr34 compared to Thatcher.