**5. Conclusions**

The Fusarium resistance testing is a very sensitive experimental system. The pathologically uncontrolled mixing and conidium concentration adjusting cannot secure the stable high aggressiveness needed to receive high differentiation of the genotypes [16–63]. Mixing and conidium concentration adjusting, which are applied without controlling by plant pathological methods, cannot secure the stable high aggressiveness needed to receive a correct data on differentiation of the genotypes. It also became clear that FDK or DON specific behavior could not be verified exactly by single inocula. In the mixing variants with the same level of DI, very diverse results for FDK and DON can be recorded. It is also sure that one isolate, or mixture, should it be selected as good as possible, provides only one pathogenic level. Without controlling for aggressiveness of the dilution, concentration or mixing can lead to artifacts. Again, without using more isolates independently, will not have the chance to present the phenotypic data that are necessary to receive reliable data for the identification and validation in medium and low effects of QTL. There are strong arguments to change the resistance testing methodology followed until now.

**Author Contributions:** Conceptualization, A.M.; methodology, A.M., A.G.; M.V., and B.T.; investigation, A.G., B.T., M.V.; data curation, A.G. and A.M.; writing original draft preparation, A.M. and B.T.; writing—review and editing, A.M., supervision, A.M.; project administration, B.T. and A.M. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors are thankful for the financial support of the MycoRed FP7 (KBBE-2007-2-5-05) and GOP-1.1.1-11-2012-0159 projects and GINOP 2.2.1-15-2016-00021 (supported by Hungarian and EU sources) and the national Hungarian TUDFO/51757/2019/ITM project, 2019–2023.

**Acknowledgments:** The authors acknowledge the kind help of Matyas Cserhati in correcting the English of the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
