Virulence of 1990-1994 collections ofUstilago avenaeandU. kollerifrom Manitoba and Saskatchewan

Virulence of collections ofUstilago avenaeandUstilago kollerisampled from oat fields in Canada during 1995-19991

“…In relation to the earlier study by Menzies and Thomas (1997), it appears that new races of the pathogen are evolving, but fortunately, new virulences are not. Both the fungicide carbathiin and the Markton resistance genes are still highly effective in controlling oat smut in the field.…”

“…Virulence to Victory, Anthony, and Atlantic within oat smut populations has previously been reported to be common in Manitoba and Saskatchewan (Nielsen 1972(Nielsen , 1977aMenzies and Thomas 1997), as well as Minnesota (Wilcoxson and Stuthman 1993). In the Canadian oat smut differential set, Atlantic contains the Victoria type of resistance.…”

“…Despite the number of isolates with similar virulence races in the two studies, one third (7 of 21) of the isolates in each study had a virulence race that was not detected in the alternate study. Menzies and Thomas (1997) determined the virulence races of smut isolates collected from oat from Bolivia and Europe. The virulence of the Bolivian isolate (U. kolleri isolate 91-185) was unique to their study and no isolate of the same race was identified in the present study.…”

“…The incidence of this virulence in oat smut popula- (Table 1). Conversely, virulence to Markton, Camas, Black Mesdag, and Fulgham has not been common in western Canada (Nielsen 1972(Nielsen , 1977aMenzies and Thomas 1997). The oat smut collections from 1995-1999 were avirulent on the oat cultivars AC Medallion, AC Assiniboia, AC Belmont, AC Preakness, and Tibor (Table 1).…”