Screening of antagonistic strains <i>Trichoderma</i> Pers. towards causative agent of root rot in apples of genus Fusarium Link.

Abstract

In recent years, in the south of Russia, fungi of the genus Fusarium Link (1809) constitute a special danger to such important agricultural perennial crops as the apple tree. Тhese fungi cause root rot, a harmful disease, which weakens the vascular organs, leading to a significant decrease in yield and even death of the plant. A literature review showed that the genus Trichoderma has great potential for the integrated protection of apple trees. In this regard, due to the lack of registered microbiological agents for the control of fusarium root rot in apple trees, the search for antagonistic strains for biotechnological control of this disease becomes relevant. In this work, the parasitic activity of strains of the genus Trichoderma against the causative agents of root rot in apple trees, namely Fusarium sporotrichioides and Fusarium oxysporum, was studied in vitro. Тhe research was carried out in 2020–2021 in the Laboratory of biotechnological control of phytopathogens and phytophages of the FGBSO “North Caucasian Federal Scientific Center of Horticulture, Viticulture and Winemaking”. Тhe research was focused on monoconidial strains of the causative agent of apple root rot: F. sporotrichioides (strain RR20XXIV/4.3) and F. oxysporum (strain RR20XXV/6.2), as well as 7 strains of the genus Trichoderma having expected antagonistic activity. Тhe activity of strains of the genus Trichoderma against fungi of the genus Fusarium was determined by the dual culture method using joint splicing on the PGA medium (potato-glucose agar). Тhe Trichocin, SP (titer 1010 CFU/g Trichoderma harzianum, strain G-30 VISR), registered against root rot for a number of crops, was used as a standard. A monoculture of the test object (strains of the genus Fusarium) was used as a control. Out of the 7 strains of antagonistic fungi, strains 20I/1 and 20II/2 showed the greatest activity against F. sporotrichioides by a dual mechanism of action, which involves competition for a nutrient medium and fungicidal parasitic antagonism; the latter strain showed hyperparasitism. Antibiotic (strain 20XIV/5) and alimentary antagonisms (strain 20II/3.2) were also detected. Strain 20XIV/5 showed antibiotic antagonism against F. oxysporum, having higher activity than the standard; strain 20I/1 showed alimentary antagonism. Тhe remaining antagonist strains showed competitive interactions for the environment.