EN
The biotechnical preparations: Biosept Active (based on a grapefruit extract) and BioZell (based on thyme oil) as well as Hypericum perforatum extract, streptomycin solution and fungicide Champion 50WP (active ingredient substance – e.i. 50% copper hydroxide) were investigated for antimicrobial effects against plant pathogenic bacteria: Agrobacterium tumefaciens, Pseudomonas syringae pv. syringae and Xanthomonas arboricola pv. corylina. The screening was carried out in vitro on three media: Nutrient Agar (NA Difco), Pseudomonas Agar F (Merck) – analogue of King B and 523. In the experiments, the agar plate method was applied. There were no statistically significant differences in the effect of streptomycin and Champion 50WP on the growth inhibition of three bacteria strains for medium 523 and Nutrient Agar and of P. syringae pv. syringae and X. arboricola pv. corylina for medium King B. It was determined that the antibacterial activity of Biosept Active and BioZell biopreparations and H. perforatum extract against Agrobacterium tumefaciens (strain C58), Pseudomonas syringae pv. syringae (strain 760) and Xanthomonas arboricola pv. corylina (strain RIPF-x13) were dependent on the strain of pathogen as well as the growth medium used. According to the research results obtained, the Biosept Active preparation and H. perforatum extract demonstrated high bacteriostatic activity against three bacterial strains grown on the Nutrient Agar medium.