Beneficial effect of Trichoderma harzianum strain Ths97 in biocontrolling Fusarium solani causal agent of root rot disease in olive trees

•Biological control efficacy of T. harzianum Ths97 on F. solani Fso14 was tested.•Ths97 inhibited Fso14 growth in vitro, and exhibited mycoparasitic activity.•Dual inoculation of Ths97/Fso14 increased olive tree protection against Fusarium rot.•Ths97 stimulated local defense machinery in olive tree roots.•Ths97 Preventive application primed olive trees by potentiating its innate immunity.