IN VITRO COMPARATIVE SCREENING OF ANTIBACTERIAL AND ANTIFUNGAL ACTIVITIES OF SOME COMMON WEEDS EXTRACTS

Herbal pesticides are gaining interest because of their cost effective and eco-friendly attributes. If this antifungal and antibacterial potency resides in weeds, it will be a great advantage. The present investigation is therefore undertaken to investigate the efficacy of three common weeds i.e., Amaranthus viridis, Lantana camara and Malvastrum coromandelianum against four bacterial species viz, Xanthomonas axonopodis, Pseudomonas syringae (gram negative bacteria), Corynebacterium minutissium, Clostridium difficile (gram positive bacteria) and major seed-borne fungi Aspergillus niger, Alternaria alternata, Drechslera biseptata, Fusarium solani were studied in vitro. The chloroform and aqueous leaf extract of these weeds were used in this study. The antimicrobial activity was tested by well diffusion method. Chloroform extract of M. coromandelianum were effective against all the four bacteria with maximum inhibition zone of 3.5cm in P. syringae while its aqueous extract showed the minimum inhibitory effect with 0.7cm inhibition zone of X. axonopodis; whereas the aqueous extract of L. camera was most active against the bacteria. Aqueous extracts of L. camera also showed good antifungal activity as compared to other weed extracts and chloroform extracts of all weeds were moderately active against seed-borne fungi tested. The antifungal components from these weeds can be used as an alternative to develop novel pesticides by replacing some chemical commercial antifungal and antibacterial for the plant diseases.