Interaction of a promising bacterial antagonist strain 11-1 Bacillus sp. with the phoma rot pathogen Plenodomus lindquistii

Phytosanitary instability of agrobiocenoses and deterioration of the general ecological situation suggest increasing use of biological plant protection means. The purpose of this research was to study the mechanism of antagonistic action of the promising antagonist strain 11-1 Bacillus sp. on the sunflower Phoma rot pathogen Plenodomus lindquistii Gruyter, Aveskamp & Verkley, as one of the stages of developing elements of microbiopreparation production technology. The interaction of the promising antagonist strain with the Phoma rot pathogen before colony adhering was expressed in the formation of spherical swellings of apical parts of hyphae, giant cells, vacuolization, and compression of cytoplasm in mycelium of the pathogen. After colony adhering, we noted sorption of bacteria along pathogen hyphae, which resulted in even greater compression of cytoplasm, destruction of a cell wall, release of contents, dissolution of substrate, and vesiculation of aerial mycelium. Death of the pathogen mycelium under co-cultivation with bacillus-antagonist occurred on the seventh-eighth day.