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The phytopathogenic fungus Pyrenophora tritici-repentis is a causal agent of tan spot. Antagonistic microorganisms can be used as a non-chemical alternative treatment against the tan spot of wheat. Bacillus velezensis BZR 336 g and BZR 517 stains were selected as the most active microorganisms and potential biocontrol agents. We found that B. velezensis strains BZR 336 g and BZR 517 exhibited antagonistic activity against P. tritici-repentis Kr-15/2016 in vitro: they inhibited mycelium growth by 72.4–94.3% and caused its degenerative changes. Treatment of seeds and plants with strains BZR 336 g and BZR 517 provided a biological efficiency of 31.2–38.4% against tan spot, while artificial inoculation of plants provided only 28.4–43.8% biological efficiency. Treatment of seeds and plants with BZR 336 g and BZR 517 in a three-year field trial demonstrated 24.6–50% biological efficiency. BZR 336 g and BZR 517 provided 5.0–7.6% additional yield. We conclude that BZR 336 g and BZR 517 are promising options for novel bioproducts that can control P. tritici-repentis tan spot.

Stem canker and black scurf caused by Rhizoctonia solani are the important diseases in potato, while spur blight caused by Didymella applanata is a major disease in red raspberry. In Western Siberia, both crops are grown predominantly in small-scale farming that requires maximal usage of biological products for plant protection instead of chemicals. We evaluated two promising Bacillus velezensis strains BZR 336 g and BZR 517 isolated in the south of Russia (45°1′N, 38°59′E) for their biological control potentials against the potato and red raspberry diseases under the more severe weather conditions of Western Siberia (55°1′N, 82°55′ E). We tested two techniques to apply biocontrol agents: (1) coating the seeds (potato tubers) and (2) spraying over the plants (raspberry canes). In each case, we estimated B. velezensis strains on two plant cultivars differed by the disease resistance. The degree of B. velezensis influence on disease incidence and severity depended on the bacterial strain, the protected plant, and its cultivar. We also demonstrated that two B. velezensis strains significantly stimulated plant growth of potato, which contributed to the plant productivity on both cultivars. The BZR 336 g strain affected the potato productivity more than the BZR 517 strain. Under the influence of both bacterial strains, raspberry yield was significantly higher compared to the control on the susceptible cultivar. These findings indicated that two southern B. velezensis strains had proved their efficacy as biological control agents in the control of the serious fungal infection of potato and raspberry plants under the more severe ecological conditions of Western Siberia. For the first time, we demonstrated B. velezensis strains potential for use as biological control agents against R. solani on potato, and against D. applanata on red raspberry.

As a result of stage screening, there were selected promising bacterial strains to create laboratory samples of biological products on their basis to protect winter wheat from the causative agents of fusarium root rot. The purpose of the work is to determine the growth-stimulating and protective effect of laboratory samples of Bacillus subtilis BZR 336g and B. subtilis BZR 517 on winter wheat plants, as well as to determine the antagonistic effect of strains on Fusarium fungi. As a result of the work, there was established a positive effect of laboratory samples on the growth, development and germination of plants in greenhouse conditions and the ability to significantly inhibit the mycelium of phytopathogenic fungi F. graminearun, F. culmorum and Microdochium nivale in laboratory conditions. The study of the samples artificially infected in a climatic chamber showed not only a high protective effect of these laboratory samples, but also made it possible to determine the regimes for their use. The conducted tests prove the viability of new bioagents as environmentally friendly plant-protective products.

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