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Species of the genera Bacillus Cohn and Pseudomonas Migula are successfully used as biocontrol agents for many mycopathogens, including Alternaria sp. To assess the bacteria antagonistic potential against Alternaria sp, we used the method of counter cultures on various nutrient media – universal and specialized. Of the 24 bacterial strains of the genus Bacillus, 18 strains were developed antagonistic activity to Alternaria sp. after 10 days of co-cultivation on the Tylona-3 medium. The maximum sterile zone (8.0 mm) was formed by bacterial strains (R-9, 5B-1, 01 cor f Bacillus sp.). 3 strains of 9 bacteria of the genus Pseudomonas, developed antagonistic activity to Alternaria sp. on Kinga B medium - 14-3 Pseudomonas sp., Oif 2-1 Pseudomonas sp., 14-4 Pseudomonas sp. The maximum antibiotic activity on potato-sucrose agar was established in strains 3-3 Bacillus sp., and K 1-1 Bacillus sp. (sterile zone 7.5 mm). All the tested bacteria most often caused one sign of antagonism – antibiosis.

To prevent phytosanitary destabilization in apple agrocenoses, it is necessary to include ecologically safe microbiological preparations in the protection systems. In the Krasnodar region in 2016 and 2019 in the field, laboratory samples of microbiological preparations were tested in the formulation “wettable powder” from the collection of the laboratory of the biological method of the FGBNU VNIIMK against Venturia inaequalis (Cooke) G. Winter. Of the 9 laboratory samples tested in 2016, the highest efficiency, approaching the effectiveness of a chemical fungicide, was shown by samples based on fungal producer strains: RK-1, XK-1 and T-2 - 76.9-92.5%. In 2019, all variants (in the amount of 4) using laboratory samples of microbiological preparations were more effective in comparison with the active substance of chemical origin. The best scab control was provided by a laboratory sample of a three-component mixed preparation based on two fungal and one bacterial producer strain RK-1 + XK-1 + B-12 - 83.0-84.9%. The isolated samples are promising for research on the creation of microbiological preparations against apple scab.

Fungi from the genus Alternaria Nees are new harmful grapes mycopathogens; they are a part of the necrotic leaf spot pathocomplex. The disease intensive development leads to more than 50% necrotisation of the leaf surface, leaving no leaf on the plant by the end of the growing season. An alternative to chemical protection against the disease is the use of biocontrol agents. For this purpose, the screening of fungal antagonist strains from the collection of the laboratory of the biological method of the Federal scientific center «V.S. Pustovoit All-Russian Research Institute of Oil crops» (FSBSI «FSC «ARRIOC») was carried out in relation to the causative agent of necrotic leaf spot of grapes Alternaria sp. by the dual cultures method on two nutrient media – potato-sucrose agar and Rudakov’s agar. Of the 27 fungal strains that were screened for the antagonistic activity to 425-3 Alternaria sp. 17 strains showed the activity. Of these, 12 strains competed for feeding area and exhibited hyperparasitism. Strains A-1 and I-3 Basidiomycota, Tr-1 Trichothecium sp. and all strains of Trichoderma sp. showed the greatest antagonistic activity on both media.

There are presented data of the first stage of the secondary screening of antagonist strains from a collection of the biological methods laboratory of V.S. Pustovoit All-Russian Research Institute of Oil Crops to the aggressive isolate of Phoma macdonaldii Boerema infecting sunflower. We used methods of ‘agar blocks’ and ‘perforated Petri dishes’. As a result of a screening of 55 antagonist strains to Phoma macdonaldii pathogen we selected 17 promising strains-producers of microbiological preparations having biological efficiency exceeding 40.0 %. In control variant without seed treatment sunflower seedlings infection was up to 76.2 %, and maximal biological efficiency of laboratory samples from fungi-producers were determined for a strain M-24 Penicillium sp. (73.8 %); from bacteria of a genus Bacillus – for a strain D-10 Bacillus sp. (74.2%); from bacteria of a genus Pseudomonas – for a strain Sgc-1 Pseudomonas sp. (73.8 %). Maximal colonizing activity were noted for fungi-producers M-24 Penicillium sp. (85.7 %) and Xk-1 Ch. olivaceum (71.4 %), as well as for bacteria of a genus Bacillus – 5B-1 B. subtilis (71.4 %) and a genus Pseudomonas – Oif 2-1 Pseudomonas sp. and 14-3 P. chlororaphis (71.4 %) against Phoma infection in control of 70.0 %.