Effect Of Acacia Raddiana Extracts On Fusarium Oxysporum F. Sp. Albedinis, The Causal Agent Of Bayoud

In the present study, a medicinal plant from algerian Sahara (South-West of Algeria), Acacia raddiana has been used (leaves, bark) to evaluate its extracts (reflux extraction with four solvents: methanol, ethyl acetate, dichloromethane, hexane) on Fusarium oxysporum f. sp. albedinis (Foa). The Foa is the causal agent of the most dangerous disease of date palm (Phoenix dactylifera L.). The preliminary evaluation has been realized by agar diffusion technique and virulence test on potato tuber tissues. The extracts that present an inhibition or decrease the relative virulence (RV) below 50% undergo phytochemical screening and direct bioautography. The bioautography has been used to localize the antifungal activity on the chromatogram and study the correlation with phytochemical screening data. Among eight extracts, five has been chosen for phytochemical screening and bioautography (2 leaves extracts and 3 bark extracts). Only six tests among 32 (22.58%) present a detectable effect. The best effect is related to bark extract with ethyl acetate (inhibition diameter: 18mm), which is a moderate effect. Some extracts show an increase in RV. On the other hand, others decrease the RV. The best effect on RV is presented by hexanic extract of bark (RV=48%). The phytochemical screening highlighted the presence of flavonoids, tannins, coumarins and alkaloids in the studied plant. The direct bioautography has demonstrated no detectable effect. According to realized analyses, we can conclude that this species contains bioactive substances on Foa but need more precise analyses. The reason is simple, in addition to synergy principle in the crude extracts; the quantity of these metabolites is low compared to the detection level.