Race Analysis of Stem Rust Inoculum and its Virulence on Commercial Wheat Varieties at Seedling in Kari-Njoro, Kenya

Stem rust (Puccinia graminis pers. f. sp. tritici) is one of important foliar diseases of an economic importance in wheat (Triticum aestivum L.) worldwide. Commercial varieties are valuable genetic resource for wheat improvement. The objective of this study was to determine stem rust race in Narok and the seedling resistance of commercial wheat varieties to stem rust race from Narok. In this experiment, five sets of stem rust differential from CIMMYT were inoculated with stem rust inoculums from Narok North District, Kenya. There were different infection types as far as stem rust virulence is concerned on the commercial varieties and the stem rust differentials. From the five sets of differentials, the inoculums from Narok were found to be TTKST (Ug99+Sr24). Twenty commercial wheat varieties were evaluated for resistance to stem rust race Ug99 in three replicates in the green house. The infection type ranged between “0” to “4” with 55% of the genotypes showing resistance which could be considered for improvement of wheat varieties. About 45% of the genotype was susceptible to Ug99 suggesting elusiveness of resistant gene for stem rust. Kingbird and robin were among the resistant varieties indication of having resistant genes. Farmers need to adopt the new varieties such as kingbird and robin for better yield.