MICROBIAL PREPARATIONS FOR CONTROL OF PHYTOPATHOGENIC BACTERIA
D.K. Zabolotny Institute of Microbiology and Virology of the NAS of Ukraine,
Department of plant pathogenic bacteria
One of the effective biological methods for plant protection against phytopathogens is the use of microorganisms able to inhibit the growth and reproduction of pathogens, which are known as antagonist strains. An important feature of the use of antagonist bacteria is their ability to exist for a long time directly in the centre of infection – within the phyllosphere and rhizosphere of plants and to synthesize highly active antimicrobial substances that inhibit the growth and development of pathogens. The purpose of this work was to determine the activity of a number of widely used domestically-produced biologicals to the most common and aggressive phytopathogenic microorganisms, to determine the possibility of expanding the range of pathogenic microorganisms susceptible to the drugs. The sensitivity of the most common and aggressive genera and species of phytopathogenic bacteria to a number of newly created biologicals was determined. Not only the declared toxic activity of biologicals, but also possibilities of their permanent effect were tested. The effect of biologicals on the bacterial phytopathogens was analysed. There were such drugs as «Mikofrend» – a mycorrhizal biological that «promotes plant nutrition and protection»; «Mikokhelp» is «the complex fungicidal-active biological for control and prevention of pathogens»; «Fitotsyd»: «the fungicidal-active biological to protect plants from diseases»; «Fitokhelp»: «the biological with antimicrobial and growth-promoting effect, against bacteriosis». The results show that the effect of drugs and their components on phytopathogens is quite strong, stable, but selective. There is substantially no option that would have a permanent effect on all tested bacterial phytopathogens. Among the phytopathogens, pseudomonads usually were the most resistant to bioagents. However, those variants that show bactericidal and bacteriostatic effect on phytopathogens are characterized by stable and prolonged effect. Variants that show high bactericidal effect (from 30-70 mm in the d zone of growth inhibition to absolute sterility – destruction of the pathogen) and medium toxicity are very promising for use. The pathogen of bacterial cancer of plants was sensitive only to those drugs which include Bacillus sp. It was found that «Phytohelp» and «Mycofriend» biologicals have antimicrobial effect against the causative agents of vegetable rotting (Pectobacterium carotovorum), bacterial cancer of plants (Agrobacterium tumefaciens), black rot of agricultural plants (Xanthomonas campestris), and cancer of tomatoes and other solanaceous (Сlavibacter michiganensis). That is, the range of effect of the «Mycofriend» can be significantly expanded, as it revealed significant activity against various pathogens of bacteriosis. In addition, «Mycofriend», as well as «Mycohelp» shows average activity (from – 18 mm in d zones of growth inhibition) on Pseudomonas fluorescens – the pathogen of spots and rots. It was also determined that titration of the drug to a higher than recommended dilution dose does not significantly alter its effect on phytopathogenic bacteria. Due to the fact that «Mycofriend» is active against pathogens of black rot, tomato cancer and cancer of other agricultural plants, its components could be an effective part of other bacterials in this group being differently targeted. «Phytocid» has antibacterial effect on P. syringae, P. fluorescens and X. campestris, which are the pathogens of black rot of plants, spots and rots. Thus, the obtained results allowed us to expand the recommendations on the use of experimental bacterials in agriculture of Ukraine and horticulture for protection against phytopathogenic bacteria.