Fusarium oxysporum is the primary cause of Fusarium wilt, one of the major diseases that harm shallots. 50% of yield can be lost due to Fusarium wilt. It is anticipated that endophytic fungus will inhibit the growth of Fusarium wilt disease in shallots. The endophytic fungi from shallot plants that have the potential to act as biological control agents for the fungal disease F. oxysporum are suggested to be chosen in this study. Using Malt Extract Agar (MEA) medium, endophytic fungi were isolated from healthy shallot plant components (roots, tubers, stems, and leaves). Using dual culture and volatile techniques, the antagonistic potential of endophytic fungi against F. oxysporum was examined. Using shallot seeds, pathogenicity studies for endophytic fungus were conducted in vitro. Twelve endophytic fungal isolates were able to impede the growth of F. oxysporum using the dual culture method; the percentage of inhibition reached 72.52% at seven days post-inoculation. The endophytic fungus was also able to stop F. oxysporum mycelial growth using the volatile compound test, with a percentage inhibition ranging from 4.08 - 27.37%. The findings of the pathogenicity test demonstrated that the four isolates posed a risk to the shallot seeds. The most successful isolate in preventing the growth of F. oxysporum was the endophytic fungus AB4D1, which is a member of the Trichoderma asperellum species.

Key word: Antagonist, DNA, dual culture, Fusarium oxysporum, shallot, volatile