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The different methods and application rates of an inoculum powder of sunflower Phoma rot pathogen Plenodomus lindquistii Gruyter, Aveskamp & Verkley for an artificial infection of seeds in the laboratory in soil were studied, the results are presented. The following methods of application of Phoma inoculum powder into soil were studied: into row, mixtures with soil, and on the bottom of a growth tray covered with a filter paper under soil. The application rates of an inoculum powder were 2.5 and 5.0 g per a row of 11 cm length; 5.0 and 10.0 g per 600 g of soil – mixing with soil and on the bottom of the growth tray. The method of application of the inoculum powder into a row in a rate of 5.0 g when the most seeds perished before sprouting were considered to be an optimal one. The sunflower infection with Phoma rot pathogen was weak in variants where pathogen powder was mixed with soil or placed under soil on the bottom of the growth tray. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

To develop environmentally safe multifunctional biological preparations, we carried out the primary screening of bacterial strains (from the collection of the biomethod laboratory of V.S. Pustovoit All-Russian Research Institute of Oil Crops) against the sunflower dry rot pathogen Rhizopus oryzae Went & Prins. Geerl. by the method of double or reciprocal cultures. 17 strains of the Bacillus genus exhibited antagonistic activity against the sunflower dry rot pathogen with two types of mechanism of action (competition for feeding area and antibiosis). Strains 01 kor f and D 1-1 Bacillus sp. competed for surface feeding area and inhibited the growth of aerial mycelium of the pathogen. We observed the maximum sterile zone in three strains: 3-3 Bacillus sp. and K 1-1 B. subtilis – 4.0 mm, and P-9 B. polymyxa – 3.0 mm. 6 bacterial strains of the genus Pseudomonas had antagonistic activity against the dry rot pathogen with one type of mechanism of action – antibiosis. Strain 12-2 Pseudomonas sp. had the largest sterile zone on potato sucrose agar (PSA) (5.5 mm), and strains 14-4 and 15-1 Pseudomonas sp. had the largest sterile zone on the King B medium (5.0 and 6.0 mm). [ABSTRACT FROM AUTHOR]