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.

Fungi of the genus Fusarium are economically significant pathogens in most wheat-growing regions worldwide. The biocontrol agents Bacillus velezensis BZR 336 g and BZR 517 were tested for growth inhibition of F. graminearum BZR 4. The results demonstrated that the strains are capable of deforming and destroying hyphae. The modified bioautography technique showed that the strains produce iturin A and surfactin, which probably explains the mechanism of pathogen inhibition. Furthermore, lipopeptides were detected and identified in two samples by the HPLC-HRMS. Compounds such as surfactin and their isomers and homologues were found in both samples. An experiment on an artificial infectious background in a climatic chamber established that the biological effectiveness of strains is close to that of chemical and biological references. Cultivation of plants with B. velezensis showed that the strains are likely to reduce the stress load. An efficacy of up to 45.0% was determined for bioagents BZR 336 g and BZR 517 in field trials, while the yield was up to 7.9 t/ha. The use of B. velezensis BZR 336 g and BZR 517 as biocontrol agents provides an environmentally friendly approach to the control of Fusarium rots on wheat, reduction of the pesticide load, and hence quality harvest.

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.

Currently, there is an active development of environmentally friendly methods of farming. However, the range of products for this type of farming system is limited. Growth stimulation is one of the mechanisms ensuring plant resistance to diseases that reduce crop yields. The aim of the work is to study the effect of laboratory samples of new biological products based on B. subtilis BZR 336 g, B. subtilis BZR 517, P. chlororaphis 245 F strains and organo-mineral fertilizers PRK White Pearl Brown (WPB) and PRK White Pearl Universal” (WPU) on plant growth and development of plants, as well as study of the possibility of their joint use for subsequent inclusion in organic farming systems or integrated plant protection. Growthpromoting ability was assessed in winter wheat and sunflower plants grown in sand in a climatic chamber. As comparison variants there were seed treatment with water (control), chemical (Dividend Star, KS) and biological (Fitosporin-M, F, B. subtilis 26 D) standards. In two plant cultures there was an expected retardant effect of the chemical standard and the growth-promoting effect of the biological standard. Statistically significant data were obtained for such a parameter as the shoot length. On winter wheat, laboratory samples provided the shoot length of 24.1-25.2 mm (an addition to the control of 3.4-8.2%), organic and mineral fertilizers - 23.9-24.5 mm (2.6-5.2%), mixtures with WPU - 23.2-24.4 mm (-0.4-4.7%), mixtures with WPB - 24.1-25.9 mm (3.4-11.2%), a significant increase in root length was not observed in this culture. On winter wheat, it is advisable to use the studied products separately. Sunflower is more responsive to the action of laboratory samples. They provided a shoot length of 13.6-14.6 mm (20.9-27.0%) and a root of 9.2-10.2 mm (4.5-15.9%). Organo-mineral fertilizers provided a shoot length of 14.2-14.5 mm (23.5-26.1%) and the root length of 10.8 mm (22.7%). Mixtures with WPU provided shoot length of 14.7-15.4 mm (27.8-33.9%), mixtures with WPB provided shoot length of 11.9-14.5 mm (3.5-26.1%), and no significant increase in root length was noted. The data obtained indicate the presence in the laboratory samples of fungicidal biological products growth-promoting properties, which vary depending on the culture and additionally used organic and mineral fertilizers. To confirm the results, additional experiments are necessary. Research in this direction will allow the rational use of the studied means of protection and increase plant yields in systems of organic, ecologized and integrated farming, and can help reduce the pesticidal pressure on agrocenoses.Conflict of interest: the authors stated that there was no conflict of interest.

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.