Resistance to multiple leaf spot diseases in wheat

Tan spot (TS), Stagonospora nodorum blotch (SNB), and Septoria tritici blotch (STB) are three major leaf spot diseases of wheat worldwide. Host plant resistance (HPR) is one of the main components in the management of these diseases in wheat. The objective of this study was to identify new sources of resistance to TS (races 1 and 5), SNB, and STB. A total of 164 wheat genotypes developed by the International Maize and Wheat Improvement Center (CIMMYT), Mexico were individually evaluated for TS, SNB and STB in spring and fall of 2006 in the greenhouse. Two experiments were conducted in a randomized complete block design with three replicates. Each replicate consisted of 164 wheat genotypes planted in cones with three seedlings/genotype in each cone and disease reaction was assessed for each race or pathogen at the two- to three-leaf stage. Based on the disease reactions, three wheat genotypes were resistant to both TS and SNB, while 13 genotypes were resistant to TS and STB. Similarly, 13 genotypes were resistant to both SNB and STB. In addition, four wheat genotypes were highly resistant to TS, SNB, and STB. These results suggest that the resistant genotypes identified in this study possess high levels of resistance to multiple leaf spot diseases and could be valuable sources for wheat improvement programs.