Reactions of western Canadian spring wheat and triticale varieties to Tilletia indica, the causal agent of Karnal bunt

The reactions of 47 Canadian wheat and triticale cultivars to Tilletia indica Mitra, the causal agent of Karnal Bunt (KB), were evaluated in the field at Centro de Investigaciones Agricolas del Noroeste (CIANO), Yaqui Valley, Mexico, during 1998 and 1999. The majority of lines and cultivars flowered during January and February, which coincided with the onset of cooler temperatures and high relative humidity required for optimum infection by the fungus. Canada Western Amber Durum (CWAD) and triticale were resistant, ranging from 0 to 6% infection. Canada Western Red Spring (CWRS) wheats were also generally resistant, but the cultivars Roblin, BW90 and Laura, and the experimental line Roblin*2/BW 553, were susceptible, ranging from 11 to 28% in treatments with the highest infection levels. Canada Western Extra Strong (CWES) wheats varied in reaction from moderately resistant to susceptible, ranging from 1 to 15% infection. Canada Prairie Spring (CPS) wheats were generally susceptible, exhibiting infection levels ranging from 5 to 31% infection in the most severely infected treatments. Canada Western Soft White Spring (CWSWS) wheats were uniformly susceptible; the highest recorded infection level among Canadian wheats was observed on AC Reed (38%) during 1999. The susceptibility of CPS and CWSWS cultivars may represent an increased risk to the establishment of KB if the fungus were to become introduced into western Canada. Key words: Karnal bunt, wheat, disease resistance, disease susceptibility