ABSTRACT
In 2002 and 2003, 1,300 isolates of Puccinia recondita f. sp. tritici were obtained from six commercial cultivars of wheat at three locations in the eastern forest-steppe region of Ukraine. All isolates were tested for virulence on an international set of eight differential cultivars. Seventeen known wheat leaf rust races and several new, unnamed races were identified. The most common races in each year were races 61, 149, and 192. In 2003, up to 20 isolates each of the seven most common leaf rust races plus 8 to 10 isolates of unnamed races were tested for virulence to 35 near-isogenic wheat lines with different single Lr genes for leaf rust resistance. Isolates were polymorphic for virulence on Lr1, Lr2a, Lr2b, Lr2c, Lr9, Lr19, Lr23, Lr26, and the combination Lr27 + Lr31. No isolates were found virulent on Lr24, Lr25, or Lr28, and few isolates were virulent on Lr9. Few isolates of known races but most isolates of the new, unnamed races were virulent on Lr19. The 35 Lr gene lines also were exposed to mixed-race inoculum in field plots to tests effectiveness of their resistance. Lines with Lr24, Lr25, and Lr28 suffered no leaf rust damage in the field, and lines with Lr9, Lr18, Lr35, Lr36, and the combination Lr27 + Lr31 showed less than 10% severity.
