The aim of the present study was to check the antimicrobial potential of eleven different aqueous leaf extracts on <i>Xanthomonas campestris</i>, <i>Agrobacterium rhizogenes</i> and <i>Aspergillus fumigatus</i> based on formation of the zone of inhibition (ZOI). <i>Prosopis juliflora</i> showed maximum and significant inhibitory effect on the growth of all the three pathogens. In case of <i>Xanthomonas campestris</i> the effect of this plant extract was almost equal to the strength of Streptomycin 10 mcg, (the metric system uses the term mcg to represent micrograms). Aqueous extracts of some plants formed low zone of inhibition. While some plant extracts were comparatively more effective against all the three pathogens (<i>Xanthomonas campestris</i>, <i>Agrobacterium rhizogenes</i> and <i>Aspergillus fumigatus</i>)