Effect of selected plant extracts on winter wheat (Triticum aestivum L.) plant growth stimulation and flag leaf infection by fungal pathogens

The aim of the study was to assess the effect of plant extracts from hemp inflorescences (H) as well as a mixture of extracts from hemp inflorescences, sage leaves and tansy leaves (M) on the stimulation of plant growth and the infection index of the flag leaf of winter wheat (Triticum aestivum L.) by fungal pathogens in a two-year field experiment. The analysis of selected biometric parameters in both growing seasons (2022/2023 and 2023/2024) showed a beneficial effect of both types of extracts, regardless of the type and concentration of the extract, on the length of ears, fresh weight of the aerial part of plants and the mass of one thousand wheat grains. The study also analyzed the intensity of the occurrence of wheat flag leaf diseases (septoria leaf blotch, tan spot of wheat, and brown leaf rust of cereals), in two growing seasons. In the case of septoria leaf blotch, the lowest infection index (IP) of the flag leaf was recorded after spraying the plants with a mixture of extracts (M) in the 2022/2023 season (4.91%) and after spraying the plants with hemp extract (H) in the 2023/2024 growing season (2.13%). Similarly, in the case of tan spot of wheat, in both growing seasons, the infection of the flag leaf with the pathogen was most effectively limited by hemp extract (H) in the 2022/2023 season: 24.43%; in the 2023/2024 season: 6.23%. In turn, the infection with brown leaf rust of cereals was strongly correlated with weather conditions, and the lowest index of infection with this pathogen was recorded only after the application of chemical protection (F: 2022/2023: 0.33% and 2023/2024: 6.38%). The presented results constitute the basis for the production of a biological preparation that will contribute to the biostimulation of plants and optimize the protection of wheat against fungal diseases.