How does Nébih perform pathological resistance tests?

The testing of plant varieties’ resistance to diseases is basically carried out in two types of experiments: economic value testing (GÉV) and provocation experiments at variety testing stations. Here, they can record the possible natural infection of pathogens, but experts often also detect a significant, sometimes severe, occurrence of one or another disease. Since there is no guarantee that the most important diseases of a plant species will occur naturally every year, it is necessary to ensure that the necessary resistance tests are carried out every year by conducting experiments with artificial infection in the most important host-parasite relationships or by conducting experiments in an area with a special microclimate that facilitates the occurrence of the pathogen. At the Nébih site in Röjtökmuzsaj, candidate varieties are artificially infected with a hypodermic needle, sprayed with pathogens, and made sick in order to screen out those that are very susceptible to a particular pathogen.

Methods for determining infection

The infection of a single plot of a given variety is the single manifestation of susceptibility or resistance. Resistance or susceptibility is when the variety has a similar infection in all series of a given experiment, and even more so if its infection develops similarly in different places and in different years. The determination of the degree of susceptibility is therefore based on the knowledge of more or less single plot infection. It is obvious that the second most important task, besides the identification of the disease, is to correctly determine the degree of infection. This can be done using different methods, which must be chosen according to the type of disease and symptoms. In the case of cereal plant species, two basic methods are known for determining the infection of individual pathogens: determining the percentage of infection (Fusarium internal eye infection – infected eye%) and assessing, i.e. estimating, the infected plant surface (powdery mildew, the range of pathogens causing leaf spot, rust fungi).

The importance of resistance tests in variety recognition

The aim of resistance tests is to determine the behavior of plant varieties towards pathogens, i.e. to decide whether a plant variety is resistant or susceptible to a given disease, and to what extent it is susceptible. The practical benefits of resistance or low susceptibility can be summarized as follows:

• In certain host-parasite relationships, it is the only means of protection (because effective chemical control is not available, e.g. viral diseases, fusarium, etc.).

• Resistant or less susceptible varieties can be considered our most effective means of protection against the development of epidemics.
• Resistance is of invaluable importance in that by reducing the number of chemical controls, the contamination of natural wildlife with chemical substances is also reduced.
• Reducing the number of chemical controls makes farming more cost-effective. Additional advantages include avoiding trampling damage caused by ground machinery, spreading viruses, etc.
• Often chemical protection is not feasible due to weather conditions (e.g. in the case of Fusarium species, rain lasting for days, mist continuously covering the plant), in such cases the most effective protection is the one inherent in its resistance.

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