Likely threat of the spread of race UG99 of <Emphasis Type="Italic">Puccinia graminis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis> on wheat in southeastern Russia

In 2013 and 2014, a Ug99 race virulent to the resistance gene Sr31 was revealed on spring bread wheat fields in Saratov oblast and its inoculum was collected under conditions of stem rust epiphytoties (with the fungus Puccinia graminis f. sp. tritici acting as an agent). In March to April 2015, when a set of soft wheat lines was artificially inoculated in a climatic chamber, the virulence of the collected inoculum to gene Sr31 was confirmed, and four monopustular clones were isolated. Based on the isolated monopustular clones of Puccinia graminis f. sp. tritici, an assessment for resistance of four lines of spring soft wheat to novel Sr-gene combinations was made.