The effect of native medical plant "Clammy Inula" (Inula viscosa L.) in combination with a low dose of the fungicide iprodione (Rovral ® ) against gray mould disease (Botryis cinerea Pers.) was evaluated in vitro and in vivo. The results revealed that the plant extract had antifungal effect on mycelial growth rate and conidial germiation of pathogen isolates. The plant extract at the concentration of 1% -4% and the fungicide iprodione at the concentration of 0.2 -9 µg•ml −1 significantly reduced the mycelium growth and germination. In addition, the plant extract at the concentration of 2% -4% and iprodione at the concentration of 300 -600 µg•ml −1 significantly reduced the disease severity (%) on bean plants compared to the controls. The reduction of mycelium growth, germination, and disease severity was positively correlated with increasing plant extract and fungicide concentrations. The combination of a low dose of plant extract and fungicide at (EC 50 ) was able to reduce disease severity of gray mold by 84%. While, plant extract and fungicide alone reduced disease severity by 46% & 39% and by 70% & 76% for the isolate (Bo5-10 and Bc 99), respectively, compared with controls. The application of water extracts of I. viscose in combination of a low dose of an effective fungicide (iprodione) can be a feasible tool in reducing gray mould disease severity, but farther studies are still needed under field conditions to evaluate efficacy against the disease under field conditions.