Influence of Interspecific Relations of Soil Micromycetes on Their Parasitic Activity

The role of interspecific competition between species of soil micromycetes (Bipolaris sorokiniana Sacc. Shoem., Fusarium poae (Peck.) Wollenw., F. oxysporum Schltdl., F. equiseti (Corda) Sacc.) on their pathogenicity and aggressiveness towards spring wheat seedlings. A comparative assessment of the degree of influence of culture fluids (CF) of soil micromycetes B. sorokiniana, Fusarium poae, F. oxysporum, F. equiseti during their individual and paired cultivation on the morphological parameters and phytosanitary condition of spring wheat seedlings of the Licamero variety was carried out. The study was carried out in the laboratory using generally accepted methods. All soil phytopathogens were characterized by high pathogenicity and aggressiveness: the decrease in germination under the action of CF of all fungi was significant and reached 16% (F. poae). The suppression of the development of seedlings reached 58.8% (F. equiseti), roots – 40.3% (F. oxysporum), coleoptile – 28.9% (F. poae), the phytomass of seedlings decreased to 53.8% (F. equiseti). The aggressiveness of phytopathogens in terms of the prevalence of root rot symptoms reached 2.9 of the economic threshold of harmfulness (ETH) (B. sorokiniana and F. poae). The pairwise competitive relationships of micromycetes reduced their pathogenicity, the CF of the combination B. sorokiniana + F. oxysporum increased root length by 16.1, phytomass by 23.8%, the combination F. poae + F. equiseti stimulated root development by 22.6, phytomass growth by 40%, the combination F. oxysporum + F. equiseti stimulated root growth by 37.1, phytomass – by 43.8% compared to the control. The increase in the prevalence of root rot symptoms under the influence of CF in pairs of cultivated species reached 32.5 times compared with the control, was expressed in pigmentation and was not accompanied by an increase in harmfulness.