Garlic is one of the most important vegetable crops in Egypt. It's naturally infected with fungal strains Alternaria alternata Aspergillus niger, A. flavus, Fusarium oxysporum, F. proliferatum and F. solani causes decayed garlic cloves, F. oxysporum was aggressive pathogen isolated from decayed cloves of the garlic (cvs Balady). Silver nanoparticles which synthesized from fungal strain Pleurotus ostreatus was used in our study to manage such disease we tested the effect of three different concentrations of silver nanoparticles (40 ppm, 70 ppm and 100 ppm) to assess their antifungal activities against the fungal causal pathogen. The experiment results indicated that all three concentration, 40 ppm, 70 ppm and 100 ppm of the nano-silver had inhibition rates and 100 ppm was the most efficient concentration and had the highest effect on the mycelial growth of pathogenic fungi and also enhanced the growth of garlic bulbs in vitro under laboratory conditions and in vivo