Medicinal Plants Extracts as Source of Antifungal Agents against Fusarium oxysporum f. sp albedinis

Fusarium oxysporum f. sp. albedinis (Foa) is a soil borne fungus causing the most serious disease of date palm (Phoenix dactylifera L.) called "Bayoud". In the present study, five medicinal plants from the Algerian Sahara (Southwest of Algeria): Limoniastrum feei (aerial part, roots), Launeae arborescens (Batt.) Murb. (aerial part, roots), Fredolia aretioides Moq. et Coss. (aerial part, roots), Asteriscus graveolens (Forsk) (leaves, stems) and Acacia raddiana (leaves, bark), were used to evaluate their extracts for antifungal activity against Foa. Two parts from each plant were used for extraction by four solvents: methanol, ethyl acetate, dichloromethane and hexane. The antifungal test was conducted using disc diffusion technique and relative virulence (RV) test (on potato tuber tissue). For both tests, four extract quantities were used (200, 400, 800 and 1,600 mu g). The relative virulence was presented as necrotic tissue weight (mg) of potato tuber tissue. Among all solvents, methanol had the best extraction yield (mean: 6.35%, minimum: 2.27%, maximum: 9.80%). The highest frequency of antifungal effect on Foa was presented by ethyl acetate extracts (32.50% of detectable effect). The best effect was observed for ethyl acetate extract of Limoniastrum feei (aerial part). The virulence test showed a decrease in RV up to 30% for ethyl acetate extract of Launea arborescens aerial part. The increase in RV was observed mostly for hexanic extract from Fredolia aretioides reflecting its high toxicity compared to the other extracts.