ANTAGONISTIC ACTIVITY OF A NEW STRAIN OF TRICHODERMA VIRIDE AND ITS EFFECT ON MICROMYCETES POPULATIONS IN THE ROOT ZONE OF CORN PLANTS

Goal. To investigate the antagonistic activity of a new strain of Trichoderma viride F-100076 and its effect on the formation of micromycetes populations in the root zone of corn plants under field conditions. Methods. The antagonistic activity of T. viride F-100076 was studied by the method of mixed (counter) cultures on wort agar using phytopathogenic fungi, which were isolated and identified in the Laboratory of Plant-Microbial Interactions. The appearance and type of relationship were registered using a scale modified by Symonian and Mamikonian. The number of micromycetes was determined by the method of soil dilutions. Isolation, accounting and cultivation of fungi was carried out according to conventional methods. Micromycetes were identified according to the determinants appropriate for a specific systematic group of micromycetes. Results. It was found that T. viride IMB F-100076 is characterized by high antagonistic activity against a wide range of phytopathogenic fungi, showing hyperparasitism as early as on the eighth day. The highest antagonistic activity of the strain was found against: Alternaria radicina, Acremonium strictum, Acremonium сucurbitacearum, Fusarium oxysporum var. orthoceras, Fusarium moniliforme var. lactis, Torula expansa (5 points on the corresponding Symonian and Mamikonian scale). Data from the mycological analysis of the sod-podzolic soil of the corn rhizosphere showed that the mycocenosis of the sod-podzolic soil of the corn rhizosphere was formed by micromycetes belonging to the genera Acremonium Link, Cladosporium Corda, Fusarium Link:Fr, Gliocladium Corda, Mucor Mich, Penicillium Link:Fr, Rhizopus Ehrenb, Trichoderma Hers, among which the most represented were micromycetes of the genus Penicillium (59 %). The total number of fungi in the control variant was 291.00 ± 79.67 thousand CFU/g of soil. The introduction of straw affected both the total number of micromycetes and the genus composition of fungi. The total number of fungi in the variant with straw increased 2.6 times and amounted to 744.00 ± 114.67 thousand CFU/g of soil. The number of representatives of all studied genera of micromycetes also increased. In addition, the introduction of straw provoked the development of fungi of Bipolaris and Fusarium genera, which can be considered a negative outcome since representatives of these species are commonly recognised as pathogens of root diseases. Application of the fungus antagonist T. viride IMB F-100076 to the soil along with straw did not significantly affect the total number of micromycetes. At the same time, a displacement of fungi of the genus Bipolaris and Fusarium from the rhizosphere of corn was registered. The number of fusaria decreased from 96.00 ± 5.44 to 23.00 ± 2.32 thousand CFU/g of soil or almost 4 times and reached the level of the control variant. Fungi of the genus Bipolaris in the variant with the introduction of trichoderma were not detected. Conclusion. The antagonist fungus T. viride F-100076, introduced into the soil along with straw, strikes root in the soil and exhibits antagonistic activity against micromycetes of the genera Bipolaris and Fusarium, which are commonly represented by root rot pathogens of many crops. Thus, the new strain T. viride F-100076 allows increasing the antagonistic potential of the rhizosphere soil of corn and protecting plants from pathogens.