*4.2. Resistance Expression*

The correlations between cultivar reactions to the 15 isolates and mixtures for DI are between r = 0.96 and 0.98, *p* = 0.001. However, we have about tenfold di fference in aggressiveness. From the 15 aggressiveness level the di fferent inocula and their mixtures represent, only 1–2 cases were found where all genotypes significantly di ffered from each other. Normally two or three genotypes should have been marked without significant di fference for the given inoculum. The data are clear that the DON contamination show closer relation with FDK than with DI. Seeing the three traits, the least reliable di fference between genotypes is at disease index; larger is at FDK and the largest is at DON. However, this depends also on ecological conditions. It occurred that a higher DI was followed a poorer FDK and DON presentation. As normally only one data set is given, which is the set of the 15 possible cases shown, is a question. It seems to be clear that one inoculum surely will not describe medium or lower resistance di fferences, with more isolates, it can be done much better, but large resistance di fferences can be identified with an aggressive inoculum with a high probability. This is a confirmation of earlier results where resistance component kernel resistance and specific DON resistance were measured [2,4,14,15,70]. Resistance expression depends on the composition of the mixture, resistance level, conidium concentration and ecological conditions, so a prediction of the result of the mixture is hardly possible.
