RESISTANCE IN WHEAT TO BLACK POINT CAUSED BY Alternaria alternata AND Cochliobolus sativus

Abstract

A 2-yr field study conducted at six locations on the Canadian prairies identified seven wheat (Triticum aestivum L. em Thell.) cultivars that consistently had low incidence of black point. These resistant wheats included the hard red spring wheat cultivars Sinton, Park, Thatcher, Benito and Era, the utility wheat Glenlea, and the soft white spring wheat line SWS15 (ICARDA 15). In separate tests, the inoculation of resistant wheat cultivars with Alternaria alternata (Fr.) Keissler or Cochliobolus sativus (Ito and Kurib.) Drechs. ex Dastur under controlled environmental conditions revealed significant differences in black point incidence. All cultivars were more resistant to A. alternata than the susceptible cultivar Fielder. Glenlea and Era were more resistant to A. alternata than all the other cultivars. Only the cultivars Thatcher, Benito, and Sinton were more resistant to C. sativus than Fielder. A test comparing black point incidence caused by the two fungi found that certain cultivars differed significantly in disease incidence caused by A. alternata and C. sativus. Cochliobolus sativus produced less disease in Fielder and Sinton than A. alternata, but the reverse was true for Glenlea. These results indicate that resistance to A. alternata and C. sativus is under different genetic control in certain cultivars.Key words: Wheat (spring), black point, Alternaria alternata, Cochliobolus sativus