Primary screening of a collection of bacterial strains against the winter rapeseed Alternaria blight pathogen Alternaria brassicicola in vitro

In order to develop environmentally safe microbiological preparations, a preliminary screening of bacterial strains from the working collection of the Biomethod Laboratory at the V. S. Pustovoit AllRussian Research Institute of Oil Crops was conducted against the winter rapeseed Alternaria blight pathogen Alternaria brassicicola (Schwein.) Wiltshire, using the dual or reciprocal culture method. Among the bacteria of the genus Bacillus, 23 strains exhibited antibiotic activity, forming sterile zones ranging from 0.5 to 9.5 mm on two nutrient media: potato sucrose agar (PSA) and Tylon3. The maximum sterile zone was observed in five strains: P9 B. polymyxa (9.5 mm), 5B1 B. subtilis (8.0 mm), B (21) B. licheniformis (7.5 mm), K 11 B. subtilis (7.5 mm) and Fz9 Bacillus sp. (7.0 mm). All nine strains of Pseudomonas bacteria exhibited antagonistic activity against the Alternaria blight pathogen, with one mechanism of action – antibiotic (0.5–10.5 mm). The largest sterile zones on PSA and King's B media were observed for strain 122 Pseudomonas sp. (3.0 and 10.5 mm, respectively).