Highly adapted obligate endoparasites of the root system, root-knot nematodes (Meloidogyne spp.), cause great damage to agricultural crops. Our research is aimed at the assessment of nematicidal activity and effectiveness of antagonist fungal and bacterial strains against the most common type of root-knot nematode in the south of Russia. By means of molecular genetic identification, it was found that in the south of Russia, the species Meloidogyne hapla Chitwood, 1949 and Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 cause galls on the roots of open-ground and greenhouse tomato. Screening of microbial agents against second-stage juvenile (J2) M. hapla was carried out in the laboratory. At the end of the experiment, two liquid fungal cultures of Paecilomyces lilacinus BK-6 and Metarhizium anisopliae BK-2 were isolated, the nematicidal activity of which reached 100.0 and 70.2%, and exceeded the values of the biological standard (Nemotafagin-Mikopro) by 38.4% and 8.8%. The highest biological efficacy was noted in the liquid cultures of P. lilacinus BK-6, M. anisopliae BK-2, and Arthrobotrys conoides BK-8 when introduced into the soil before planting tomato. The number of formed galls on the roots was lower in comparison with the control by 81.0%, 75.5%, and 74.4%.

Background: In the South of Russia, due to the large acreage of tomato crops (Solanum lycopersicum Mill.), there is an acute problem of plant protection against the obligate endoparasitic of the root system Meloidogyne hapla Chitwood 1949. The aim of this study was to assess the nematicidal activity of fungal strains isolated from the rhizosphere of tomato plants infected with root-knot nematodes (RKN) (Meloidogyne spp.). Results: After conducting route surveys, 10 soil samples were selected from the rhizosphere of tomato plants affected by RKN. Fifteen isolates of fungi belonging to different species were isolated from the soil samples. The species composition of the isolated fungal strains was determined: Metarhizium anisopliae IG01, Penicillium citrinum IG02, Trichoderma harzianum IG03, Aspergillus niger IG04, Trichoderma ghanense IG05, Trichoderma harzianum IG06, Trichoderma atroviride IG07, Aspergillus awamori IG08, Trichoderma atroviride IG09, Paramyrothecium roridum IG10, Trichoderma atroviride IG11, Trichoderma hamatum IG12, Beauveria bassiana IG13, Aspergillus ochraceus IG14, Purpureocillium lilacinum IG15. After initial screening in the laboratory, strains with the greatest nematicidal activity and safe for humans were selected: M. anisopliae ИГ01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09. The mortality rate of RKN when using these fungal strains varied from 79.4 ± 1.8 to 93.9 ± 3.1%. In the greenhouse, the fungal strains M. anisopliae IG01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09 showed high results in reducing the number of galls on the roots of tomato plants, and their biological efficacy was 71.4–83.0%. Conclusion: Work on the study of the nematicidal activity of fungi, in vitro and in vivo, allows us to conclude that strains isolated from the rhizosphere of plants can be effective in combating the north RKN (M. hapla). In the future, it is planned to establish the compatibility of M. anisopliae IG01, T. harzianum IG03, T. ghanense IG05, T. atroviride IG07, T. atroviride IG09 with each other and selecting the ratios of the studied strains to obtain mixtures to create an effective biological nematicide.

Aim. To determine the nematicidal activity of native bacterial isolates from the rhizosphere of tomatoes affected by the northern root‐knot nematode Meloidogyne hapla.The study was carried out using bacterial isolates obtained from the rhizosphere of a tomato affected by meloidogynosis, the species of which was determined using DNA nucleotide sequence analysis. The analysis was carried out on a DNeasy Plant Mini Kit and the results were compared using the Unipro UGENE program. Nematicidal activity was calculated based on the number of dead nematodes counted using a microscope.From the rhizosphere of tomatoes infected with the northern root‐knot nematode Meloidogyne hapla, 10 isolates of antagonist bacteria were isolated into a pure culture and identified. To consider their safety for humans and warm‐blooded animals, 7 of these were tested for nematicidal activity. According to the data obtained, the use of 5 studied bacterial strains caused mass mortality of northern root‐knot nematode larvae, starting from 24 hours and reaching 92.2–97.2 % by 96 hours after the start of the experiment.Bacterial strains Bacillus thuringiensis IB17 (titer 1x10⁵, CFU/ml), Pseudomonas silesiensis IB18 (titer 1x10⁶, CFU/ml), Bacillus mycoides IB19 (titer 1x10⁸, CFU/ml), Glutamicibacter arilaitensis IB23 (titer 1x10⁶, CFU/ml), Pseudomonas silesiensis IB24 (titer 1x10⁷, CFU/ml) exhibits high nematicidal activity against M. hapla larvae and can be used to create bionematicides.