Evaluation of Trichoderma harzianum as a biocontrol agent against vascular fusariosis of date palm (Phoenix dactylifera L.).

Date palm (Phoenix dactylifera L.) is qualified as a 'tree' of great ecological and socio- economical importance in desert oases. Unfortunately, this tree suffers from vascular fusariosis commonly named bayoud, caused by Fusarium oxysporum f.sp. albedinis (Foa). Bayoud is the most destructive fungal disease of date palm (Phoenix dactylifera L.). The impact of this disease is most severe in North Africa particularly in Morocco where 2/3 of palm trees were destroyed so far (Fernandez et al., 1995Fernandez et al., 1995). In this work, Trichoderma harzianum was tested to determine its effect on the mycelial growth of Fusarium oxysporum f. sp. albedinis (Foa) in dual culture and its control of fascular fusariosis disease in pot-grown date palm sets. In vitro and in vivo antagonistic effect of Trichoderma harzianum against Fusarium oxysporum f. sp. Albedinis, tests of direct confrontation, on PDA medium or remote confrontation, between Fusarium oxysporum f. sp. albedinis and Trichoderma harzianum, revealed that the latest has inhibited mycelial growth of the pathogen by more than 65% compared to the control and this after an incubation period of about four days at 25°C. Moreover, beyond this period and after six days, T. harzianum invades and also sporulates on Fusarium oxysporum f. sp. albedinis colonies revealing its high myco-parasitism. Some In pot experiments, where the soil was inoculated with a pathogenic isolate of Foa and a biocontrol agent T.harzianum. T. harzianum inhibited mycelial growth of the pathogen in vitro…. This study suggests the possible role of T. harzianum in the induction of antifungal compounds against F. oxysporum f. sp. Albedinis.