ACTIVITIES OF SOME ANTIFUNGAL AGENTS AGAINST PHYTOPATHOGENIC YAM ROT FUNGI SPORES IN ZARIA, NIGERIA

ACTIVITIES OF SOME ANTIFUNGAL AGENTS AGAINST PHYTOPATHOGENIC YAM ROT FUNGI SPORES IN ZARIA, NIGERIA

Abstract:

Postharvest deterioration has been a major problem associated with yam storage for both farmers and traders and it is caused mostly by micro-organisms especially fungi. The antifungal activity of some commonly used anti-dermatophytic agents (Fluconazole, Terbinafine Hcl, Ketoconazole, Sodium propionate and Griseofulvin) against phytopathogenic fungi such as Aspergillus flavus, Aspergillus niger, Penicillium citrinum and Rhizopus stolonifer spores were investigated. The sensitivity of phytopathogenic isolated fungi spores to test antifungal agents were carried out using zone of inhibition, Minimum Inhibition Concentrations (MICs), Minimum Fungicidal Concentrations (MFCs), Fractional Inhibitory Concentrations (FICs) and Fractional Fungicidal Concentrations (FFCs) to measure the antifungal activities of the test antifungal agents, their fungi toxic effects against A. flavus, A. niger, P. citrinum and R. stolonifer was found to be in the order of: Terbinafine Hcl > Fluconazole > Ketoconazole > Sodium propionate > Griseofulvin The in-vitro MICs of the antifungal agents for example Terbinafine Hcl against A. flavus, A. niger, P. citrinum and R. stolonifer were 1.0, 10.0, 1.0, and 50.0μg/ml respectively. This is an indication that R. stolonifer is the most resistant phytopathogenic fungal spores in this investigation against the observed potent antifungal agents in this study. The effects of fungicidal concentration of the different antifungal agents against viable test fungi spores number at different time interval showed rapid lethal effects. The six potential fungicides combination observed in this study, viz: Terbinafine Hcl, Fluconazole and Ketoconazole in combination each with either Sodium propionate or Griseofulvin displayed synergistic activity with value of FIC 0.19 to 0.83 against the test phytopathogenic fungal spores. The antifungal effects of evaluated fungicide combinations were observed to be stable at temperature ranges of 35-70ºC, but effect reduced as the temperature increased to 100 ºC. At acidic pH, there was general reduction in the antifungal effects of these combinations, but at neutral and alkaline pH the antifungal effects increased. Within six months storage of these combinations, antifungal effects were stable and sustainable. The in-vivo antifungal activity shows that these formulated fungicide combinations can be used to preserve yam as they inhibited Aspergillus niger and Rhizopus stolonifer (1.5 x 106cfu/ml) spores on sliced old and new yam.

ACTIVITIES OF SOME ANTIFUNGAL AGENTS AGAINST PHYTOPATHOGENIC YAM ROT FUNGI SPORES IN ZARIA, NIGERIA