SENSITIVITY OF QUARANTINE PHYTOPATHOGENS (CERCOSPORA KIKUCHII, COCHLIOBOLUS CARBONUM, DIAPORTHE HELIANTHI) TO A NUMBER OF ACTIVE FUNGICIDES INGREDIENTS

The objective of this study was to evaluate the biological effectiveness (BE) of nine active ingredients of fungicides from different classes (benzimidazoles, triazoles, antildes, strobilarins) against three species of phytopathogenic fungi quarantined for the EAEU: Cercospora Kikuchi, Diaporthe helianthi, Cochliobolus carbonum, and their closely related species (Cercospora sigma, Diaporthe novem, Helminthosporium maydis). The studies were conducted in 2025 in the mycology laboratory of the All-Russian Plant Quarantine Center (FSBI All-Russia Plant Quarantine Center). In vitro tests were conducted on potato dextrose agar, and the effects of the substances were assessed at four concentrations (10, 50, 100, and 200 mg/L). Data were collected on day 14. Biological effectiveness (BE, %) was calculated relative to the control. It was established that susceptibility was species-specific: C. Kikuchi was effectively inhibited mainly by triazoles (prothioconazole >100 mg/L), while strobilarins, antildes, and benzimidazoles were weakly effective; C. sigma retained high susceptibility to almost all classes. For C. carbonum and H. maydis, triazoles provided primary inhibition (up to 100%), strobilarins and antildes showed a partial dose-dependent effect, and benzimidazoles were less effective. D. helianthi was completely inhibited by triazoles and high doses of benzimidazoles, and D. novem responded only to triazoles and benzimidazoles, not to strobilarins and antildes. The obtained data confirm the need for species-specific specification in registration and methodological materials and indicate the feasibility of using protection schemes based on triazoles and rotation of mechanisms of action.