Effect of entomopathogenic fungus Metarhizium robertsii on disease incidence of Faba beans (Vicia faba L.) in field conditions

Abstract

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.

Biopriming of broad bean seeds with entomopathogenic fungus Metarhizium robertsii J.F. Bisch., S.A. Rehner et Humber, 2009 does not affect invertebrate communities of the agroecosystem

“…This work is a part of a comprehensive study of the eff ect of endophytes on the entire agricultural system of the broad bean fi eld, including agricultural plants, fungi and invertebrates, both pests and accompanying species. The characteristics of the colonization of plant tissues and rhizosphere soil by the fungus M. robertsii, as well as the eff ects on plants, are detailed in our previous work [Ashmarina et al, 2022]. We found that soaking broad bean seeds with M. robertsii conidia before planting led to signifi cant decrease in the intensity of plant diseases (root rot, powdery mildew, spotting) even at a relatively low level of plant colonization by the fungus.…”

“…In June, the colonization of internal tissues of stems and root surfaces reached 18 % and 36 %, respectively, compared to 4 % of Metarhizium-positive plants in the control. In the following months (July-August), the level of colonization decreased to the control values [Ashmarina et al, 2022].…”

“…In addition, this treatment stimulated the formation of active nodules on the roots, increased plant biomass and the yield of beans in agroecosystems in Western Siberia. 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 [Ashmarina et al, 2022].…”

“…The treatment of plants was carried out by soaking the seeds according to the previously described method [Tomilova et al, 2019;Ashmarina et al, 2022]. Conidia were suspended in a water-tween solution (Tween-20, 0.04 %) with a fi nal concentration of 5 × 10 7 conidia/ml.…”

“…Metarhizium robertsii (strain P-72, Genbank #KP172147) from the collection of microorganisms of the ISEA SB RAS was used in the study. Fungal conidia were cultivated on autoclaved millet as previously described [Ashmarina et al, 2022]. Concentrations of conidia were determined using a Neubauer hemocytometer.…”