Biologically manufactured silver nanoparticles are increasingly being used for various sterilization purposes because of its broad spectrum antibacterial activity. There have been relatively few studies on the applicability of silver NPs to control plant diseases. The present study was aimed to investigate the potential of green synthesized silver nanoparticles (GAgNPs) to analyze disease burden in poppy plants affected with Downy mildew (DM) disease caused by fungi Peronospora arborescens for the first time. The GAgNPs was also assayed to determine its antimicrobial potential against bacterial strains. We found that there were some bacterial strains in addition to the fungus which affected the crop yield, by measuring colony forming unit (CFU), caused disease burden on poppy plants. In in vitro examination shows, GAgNPs significantly inhibited bacterial strains even at 10 ppm (least minimum inhibitory concentration (MIC)) then control. Maximum inhibition shows at 100 ppm (most MIC) which is an optimize concentration of GAgNPs. These results suggest that GAgNPs have potential for use as economic, low-dose, potentially non-persistent anti-microbial agents against both DM fungi and the bacterial strains. Copyright © 2017 VBRI Press.