A multiple disease test for field-based phenotyping of resistances to Fusarium head blight, yellow rust and stem rust in wheat

Wheat is affected by many diseases, in Germany eight fungal diseases are recorded during the cultivar registration process. For a commercially successful cultivar, therefore, at least moderate resistances to important diseases, like yellow rust (YR) and Fusarium head blight (FHB), are necessary. Additionally, in 2013 a regional stem rust (SR) epidemic occurred in Central Germany for the first time for decades. Our objective was to analyze the resistance of 36 commercially grown winter wheat cultivars to YR, FHB, and SR in three individual and one combined inoculation. Appreciable disease severities were achieved for YR and FHB at three to four locations in two years (= seven location × year combinations), for SR at one to two locations in two years (= three location × year combinations). Wheat cultivars showed a significant genotypic variation for all diseases with high heritabilities (0.90–0.95). Interaction between inoculation treatments (individual vs. combined) and wheat genotype was not significant for each of the three diseases. Accordingly, correlations between both inoculation treatments were very high (R2 = 0.95–0.99). Several cultivars showed multi-disease resistance (MDR) to YR, FHB, and SR. In conclusion, resistance ranking among genotypes was not changed when plants were challenged with all three pathogens together compared to factorial inoculations of only one of them. Substituting factorial inoculation trials by multi-pathogen inoculation makes it more efficient to select for MDR in practical breeding programs.