Abstract—: The effect of pre-sowing treatment of soft wheat seeds of the Darya (K-64432) and Leningradskaya 6 (K-64902) varieties using biologically active chitosan with or without the crosslinking agent glyoxal has been evaluated. Two methods of glyoxal administration have been considered: after the treatment with chitosan and simultaneously with chitosan. The phytometric characteristics of the crops, as well as the phytopathological and other indicators of disease development, have been analyzed. Regardless of the processing method, wheat productivity has been shown to increase significantly (by 188%), with the optimal chitosan solution concentrations being 5% for the Darya variety and 6–7% for the Leningradskaya 6 variety. Sequential treatment with chitosan and glyoxal has been found to be the most effective method, particularly reducing the incidence of powdery mildew in the Leningradskaya 6 variety (BE = 95.7%).