Meloidogyne incognita Kofoid et White is one of the most dangerous root-knot nematodes in greenhouses. In this study, we evaluated two Bacillus strains (Bacillus velezensis BZR 86 and Bacillus velezensis BZR 277) as promising microbiological agents for protecting cucumber plants from the root-knot nematode M. incognita Kof. The morphological and cultural characteristics and enzymatic activity of the strains have been studied and the optimal conditions for its cultivation have been developed. We have shown the nematicidal activity of these strains against M. incognita. Experiments with the cucumber variety Courage were conducted under greenhouse conditions in 2016–2018. We determined the effect of plant damage with M. incognita to plants on the biometric parameters of underground and aboveground parts of cucumber plants, as well as on the gall formation index and yield. It was found that the treatment of plants with Bacillus strains contributed to an increase in the height of cucumber plants by 7.4–43.1%, an increase in leaf area by 2.7–17.8%, and an increase in root mass by 3.2–16.1% compared with the control plants without treatment. The application of these strains was proved to contribute to an increase in yield by 4.6–45.8% compared to control. Our experiments suggest that the treatment of cucumber plants with two Bacillus strains improved plant health and crop productivity in the greenhouse. B. velezensis BZR 86 and B. velezensis BZR 277 may form the basis for bionematicides to protect cucumber plants from the root-knot nematode M. incognita.

ISOLATION AND CHARACTERIZATION OF ANTIFUNGAL METABOLITES OF Bacillus subtilis STRAINS BZR 336G AND BZR 517 USING THE MODIFIED BIOAUTHOGRAPHY METHOD Т.М. Sidorova, А.М. Asaturova, A.I. Homyak, N.S. Tomashevich

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 studies were carried out to search for bacterial strains with growth-stimulating activity. Eighty strains were evaluated during the experiments. The Ba