Abstract: The study was carried out during June-September 2001 at the Department of Botany, University of Karachi. Present investigation concluded that aqueous extract of Conyza canadensis had no significant impact on egg hatch of Meloidogyne javanica in vitro. However, aqueous extract of C. canadensis caused considerable mortality of M. javanica juveniles at 24 h but not at 48 h. Ethanolic extract of powdered shoot of C. canadensis did not exert any inhibitory effect on radial growth of root-infecting fungi including Macrophomina phaseolina, Fusarium solani and Rhizoctonia solani in vitro. Soil amendment with powdered shoot of C. canadensis at 5% concentration significantly reduced galling due to M. javanica in mungbean roots grown in non-sterilized soil but not in sterilized soil. C. canadensis at 2.5% concentration did not affect root-knot development in either of the soil types tested. Soil amendment with 5% C. canadensis in non-sterilized soil markedly reduced plant height and fresh weight of mungbean shoots. Fresh root weights were markedly lowered, in both sterilized and non-sterilized soil, amended with 5% C. canadensis. C. canadensis suppresses root-knot nematode disease indirectly by enhancing soil microbial assemblages, particularly the microfungi antagonistic to root-knot nematodes.