In 2016–2018 virulence of the Czech wheat leaf rust population was studied on Thatcher near-isogenic lines, carrying different Lr genes, and 130 leaf rust isolates. Virulence to Lr9 was found only sporadically. Virulence frequency to Lr2a, Lr2b, Lr2c and Lr28 was lower than in previous years. All tested isolates were avirulent to Lr19. Lr24 conditioned resistance to majority of isolates. Nineteen recently registered Czech cultivars were tested with six isolates of the pathogen and Lr genes were postulated. Presence of genes Lr1, Lr10, Lr19, Lr24, Lr26, Lr28, Lr34 and Lr37 was tested by molecular markers. Lr37 prevailed, followed by Lr genes 10, 24, 28, 1 and 26; genes Lr19 and Lr34 were not determined.

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Leaf rust (caused by Puccinia triticina Eriks-Pt) occurs regularly in the Czech Republic and can inflict considerable yield losses on wheat, particularly in the southeastern part of the country in warm and dry years. Knowledge of resistance genes (Lr) is useful in the breeding, particularly when combined with data on virulence in the rust population. Seeds of 56 winter wheat cultivars registered in the Czech Republic were obtained from the Central Institute for Supervising and Testing in Agriculture. All cultivars were tested by molecular markers to postulate the presence of Lr1,