Ageratum conyzoides L. is an allelopathic weed. The present study was conducted to investigate the antifungal activity and allelopathic affects of A. conyzoides against Fusarium solani (Mart.) Sacc. which is a devastating pathogen on various plants. Different types of extracts i.e. aqueous, methanol and n-hexane of all vegetative plant parts e.g. inflorescence, leaf, stem and roots of A. conyzoides were tested for their antifungal activity in various concentrations. Leaf extracts proved to be most inhibitory and among all concentrations highest concentration markedly reduced the biomass production as compared to the lower concentrations. It is evident from present findings that A. conyzoides has the potential to control the growth of F. solani. Further studies were done to check the genetic variability among same pathogen isolated from different sources. Molecular characterization of F. solani revealed that isolate V3 (Lycopersicum esculentum Mill.) and V5 (Solanum melongena L.) have the highest percentage similarity.