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The treatment of agricultural crops with entomopathogenic fungi may disturb the structure of soil microarthropod communities, which can have an adverse impact on soil fertility and, ultimately, on the yield. The effect of the treatment of broad bean (Vicia faba L.) seeds, with the entomopathogenic fungus Metarhizium robertsii, on the abundance and community structure of soil microarthropods in the rhizosphere was assessed in different phases of plant vegetation in a two-year experiment. Under the conditions of the gradually decreased abundance of M. robertsii both in the soil cenoses and in the plants during summer, no adverse effect was revealed of the bean seed treatment, with the entomopathogenic fungus, on the abundance of soil microarthropods (Acari: Mesostigmata, Prostigmata, Oribatida and Astigmata; Collembola) and the structure of their communities. Similar results were obtained in the analysis, taking into account the positive colonization of plants. Some changes in the microarthropod community structure were explained primarily by the spatial heterogeneity of the field, the hydrothermal regime, and the features of the microarthropod life cycles. The results indicate the possibility of using dressing seeds with conidial suspension for plant inoculation with entomopathogenic fungus (at least M. robertsii) as a potentially safe plant protection method for non-target soil microarthropods.

The research was carried out to study the influence of biologization and chemicalization factors on the phytosanitary state of barley in the chain of the six-field fodder crop rotation of the second rotation in the forest-steppe of Western Siberia. The biologization factor was considered sowing peas to barley. The chemicalization factor was considered as the introduction of mineral fertilizers according to the results of agrochemical analysis at a dose of N60P20. It was found that the highest development of root rot was found in the variant with sowing barley without fertilizers, where the disease development index reached an average of 14.4% for the plant. The lowest one is in the variant “barley + peas + fertilizers’ (4.6%). In the variants “barley + peas’ and “barley + fertilizer”, the intensity of the disease was approximately the same and within the limits of the severity threshold – from 6.6 to 6.9 %. Similar data were obtained for the prevalence of the disease. Among the analyzed organs, the primary roots had the greatest damage, which was due to significant infection with Bipolaris sorokiniana Sacc. Damage by leaf-stem infections was almost 2 times lower in the variant with the use of the legume component and the application of fertilizers (16.8%) versus the control variant (31.8%). It was found that the correlation coefficient of the root rot development index on average for a plant with productive tillering was r = –0.63, and with plant height r = –0.99. Confirmation of the harmfulness of root rot is a close negative correlation between the yield and the indicators of the development of the disease on average for the plant: r = –0.74. It was found that the most favorable phytosanitary situation developed in the variant of sowing barley with the use of fertilizers and a legume component, which is associated with the healing effect of fertilizers and legumes, which is reflected, on the one hand, in increasing the endurance of the plant itself, and on the other, in an inhibitory effect on causative agents of the disease.

Faba beans (Vicia faba L.) are affected by a large number of pathogens. Studies carried out in western Siberia revealed the influence of the entomopathogenic fungus Metarhizium robertsii on reducing the development and prevalence of a complex of diseases in faba bean in the field. There was a decreasing tendency of the level of phytopathogen infection of seed material and fragments of underground organs during presowing treatment of the bean seeds with M. robertsii. Treatment with M. robertsii significantly reduced the development of root rot by 2.9 and 9.5 times in 2019 and 2020, respectively, and the prevalence of the disease decreased by 2.9-3.0 times. It also resulted in reduction of the severity of diseases of aerial organs during the growing season on average for the plant: the disease development index (DDI) of powdery mildew by 3.8 times and chocolate spot by 3.5 times. There was a significant increase in the number of active nodules on the roots of plants during the treatment with M. robertsii. The results obtained indicate that the treatment of bean seeds with the entomopathogenic fungus M. robertsii improved the phytosanitary situation of the sowing of the crop, and in the future, this technique can be used in agricultural practice.

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