Wheat stem rust (SR), caused by Puccinia graminis f. sp. tritici (Pgt) is a destructive disease that can cause severe yield losses in cereal crops. A new Pgt race (TTRTF), first identified in Sicily in 2016, has overcome many important SR resistance genes and in 2017-2018, SR was reported on wheat and barley in other European countries. There is an urgent need to identify new and effective sources of resistance to SR in the European cereal germplasm. Seedlings of 151 bread wheat, 3 barley and 19 triticale cultivars from 11 European countries were evaluated at the seedling stage for resistance to the SR races TTRTF,TTKSK, TTKST, TTKTK, TTKTT and TKTTF at the rust quarantine greenhouses in Denmark. The races were confirmed by comparing the SSR genotype of the isolates used in this study to the reference isolates representing the clades defined by CDL, Minnesota, USA. All isolates of the Ug99 races grouped within Clade I, the isolates of TTRTF and TKTTF belonged to Clade III-B and Clade IV-A respectively. At the seedling stage, experimental procedures for inoculation, incubation, and disease assessment were done according to Jin et al. 2007. A number of cultivars have been selected for resistance phenotyping at the adult plant stage and are carried out during spring 2019, using airbrush sprayer with spore suspension of each race for inoculation at the booting stage. The results of the seedling test have indicated that only 3 (2%) of the wheat cultivars and none of the barley cultivars were resistant to all tested races. In contrast, 16 (84%) triticale cultivars were resistant to the tested races. SR resistant wheat genotypes should be investigated further to resolve the genetic basis for resistance, and identify which linages that could potentially be used as donor parent inbreeding programs. The high proportion of SR susceptible cultivars in this study confirm the urgent need for additional focus on breeding for resistance to wheat SR in European cereal breeding programs.

Acknowledgement. The work is funded by the Danish Innovation Fund (MULTIRES), European Union's Horizon 2020 research and innovation programme under grant agreement No 773311 (RustWatch) and Swedish Board of Agriculture. 020287