Cephalosporium Stripe Resistance and Grain Yield Potential of Wheat Lines with Strawbreaker Resistance Derived from Aegilops ventricosa. D. E. Roberts, Former Graduate Student, United States Department of Agriculture, Agricultural Research Service, Department of Agronomy, Washington State University, Pullman 99164-6420. R. E. Allan, Geneticist, Plants, United States Department of Agriculture, Agricultural Research Service, Department of Agronomy, Washington State University, Pullman 99164-6420. Plant Dis. 74:852-857. Accepted for publication 30 April 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0852.

Wheat (Triticum aestivum) having germ plasm of Aegilops ventricosa for resistance to strawbreaker (caused by Pseudocercosporella herpotrichoides) has not previously demonstrated the yield potential or the resistance to Cephalosporium stripe (caused by Cephalosporium gramineum) of certain adapted northwestern U.S. cultivars. Fifteen genotypes homozygous for an endopeptidase isoenzyme of A. ventricosa closely linked to strawbreaker resistance, as shown by starch gel electrophoresis, suffered no yield loss attributable to strawbreaker in three seasons of field testing. Yields among the 15 genotypes varied under pressure from C. gramineum. Reactions among genotypes to the two pathogens were expressed independently and lines with resistance to both pathogens were identified. Ten F₂-derived sibling pairs were grown under strawbreaker pressure for three seasons, with disease and control treatments. Seven pairs had contrasting reactions to strawbreaker but their yield potentials were generally similar. The incorporation into wheat of high strawbreaker resistance, derived from A. ventricosa, should not reduce genetic yield potential.