The paper presents the results of a multi-year assessment of wheat resistance to yellow rust on an artificial infectious background in the field. The dynamics of the disease in the differentiator-varieties with identified resistance genes is studied. The formation of new races of the pathogen after its epiphytoties is revealed. The loss of resistance of certain genotypes that had "effective genes" and were resistant to the disease at the beginning of the experiment is registered. The age resistance of plants, which is of great importance in breeding of resistant varieties of wheat, is analyzed.