Biocidal and resistance-inducing effects of chitosan on phytopathogens

In connection with the of the law adoption on organic products in the Russian Federation, as well as the appearance of fungicide-resistant forms of phytopathogens, the search for new preparations of biological origin for plant protection from disease remains relevant. Chitosan is a promising substance obtained from shells of crustaceans, zygomycete fungi: on the one hand, it prevents the pathogen's penetration into the plant inducing a horizontal resistance, and on the other, it has a bactericidal effect against some bacteria and fungi. This article shows the biocidal effect of chitosan hydrolysate with a molecular weight of the main fraction of 33.7 kDa in relation to 5 phytopathogenic bacteria. The minimum bactericidal concentration ranged from 0.25 to 0.5%. It was noted that the substance acts more actively against Gram-negative bacteria than in relation to Gram-positive. Biological substance efficacy on artificial infectious background of cucumber downy mildew during preventive treatment amounted to the average of 55.4% compared to control with no treatment.