Grapevine dieback is an increasing concern in Morocco, where fungal pathogens, particularly Fusarium species, are involved in disease development. This study aimed to isolate, identify and evaluate the pathogenicity of Fusarium species associated with symptomatic grapevine plants. Fungal isolates were obtained from symptomatic tissues and then identified using morphological and molecular approaches, Analyses revealed the presence of isolates belonging to Fusarium solani (R1 and R3), Fusarium falciforme (R2 and A46), and Fusarium chlamydosporum (D11). Pathogenicity was evaluated using herbaceous stem inoculation assay on grapevine. All isolates were pathogenic, inducing progressive vascular lesions and foliar symptoms typical of Fusarium dieback. At 14 days post inoculation (dpi), isolate R1 was the most aggressive, with a 25.67 ± 10.52 mm lesion length and 52.1 % height reduction compare to the control. This growth inhibition was directly associated with the expansion of the necrosis, causing stem dieback and structural collapse. The isolate R2, A46 and D11 exhibited intermediate levels of aggressiveness. At this stage, the foliar disease severity was significantly higher in all infected plants. By 21 days, the whole plant disease severity index reached 100 %, confirming a lethal systemic infection. The pathogen was successfully re-isolated from symptomatic tissues, fulfilling Koch’s postulates. To our knowledge, this study represents the first report of F. solani and F. falciforme associated with grapevine in Morocco. Overall, this study highlights the diversity and pathogenicity of Fusarium species associated with grapevine dieback in Morocco and demonstrates the effectiveness of herbaceous stem inoculation for pathogenicity assessment.