Bayoud caused by Fusarium oxysporum f.sp. albedinis (Foa), is the most destructive disease of the date palm (Phoenix dactylifera L.) in Morocco and Algeria and there is no effective control strategy. We found that although Foa isolates vary morphologically, Foa strains can be identified by species-specific primers. PCR analysis revealed that the strains that we isolated from infected date palm rachis were the Bayoud pathogen Foa. We used these strains to evaluate the antifungal activity of tar extracted from Acacia tortilis subsp. raddiana. The A. raddiana tar had a density of 1.15, a refraction index of 1.3850, a pH of 5.2 and a dried matter ratio of 48.75%. The A. raddiana tar effectively inhibited the growth of Foa in vitro with a minimum inhibitory concentration of 3 µg/ml.

Bayoud, a vascular disease of date palm, caused by Fusarium oxysporum f. sp. albedinis (FOA) is the most damaging disease of date palm in Algeria, with no effective control strategy yet available. This research aims to esti-mate the antifusarium activity of the Olea europaea subsp. sylvestris tar growing in Bechar (Algeria) against FOA, the cause of Bayoud disease of the date palm. The values of physicochemical analysis of the tar such as density value, index of refraction, pH and dry matter percentage were also deter-mined. In order to identify FOA pathogenic isolates, a specific PCR assay was used to verify that the isolated strains were the Bayoud pathogen FOA. Tar extracted from O. europaea subsp. sylvestris was tested for its antifungal activity against FOA. The physicochemical analysis results of vegetable tar showed a density value of 1.08, an index of refraction 1.5110, a pH of about 3,7 and 35% of dry matter. The specific PCR analysis allowed absolutely that all the isolates corresponded well to the Bayoud pathogen. The results of the antifungal activity revealed that the O. europaea subsp. sylvestris tar has a great percentage of inhibition against FOA, with minimal inhibition concen-tration value 2,1 μg/ml. This confirms the possible implication of vegetable tar in triggering date palm defence against its pathogen and confers a prom-ising strategy for effective control of the bayoud disease.