Abstract

Kabera Justin, Ugirinshuti Viateur, Ntahonshikira Charles, Nteziryayo Emile and Niyondora Martin

An assay of antifungal activity of essential oils of Ocimum urticifolium and Cymbopogon citratus was conducted to assess their potentials in controlling potato mildew in Irish potato. The disc diffusion method was used to evaluate the zone of fungal growth inhibition while the oil-supplemented medium was used to evaluate the antifungal activity of these essential oils at various concentrations. These essential oils were used to cure the infected plants as ex situ investigation. The results revealed that the essential oils exhibit fungicidal activity against P. infestans at higher concentrations. In vitro antifungal activity was recorded with the minimum inhibitory concentrations ranging from 200 to 10 μl/l and from 600 to 400 μl/l for the essential oils of O. urticifolium and C. citratus, respectively. The essential oil of O. urticifolium was more efficient than the essential oil of C. citratus and the ex situ investigation succeeded in curing infected plants. The eugenol and citral were described to play the major role in imparting the antifungal activity to this oil. The fungistatic effect against P. infestans was observed. These results indicate the possibility of exploiting O. urticifolium and C. citratus in fighting P. infestans which causes heavy losses of Irish potato.