Corynespora cassicola, Curvularia sp., Curvularia lunata, Fusarium oxysporum, F. monilifonne, Monilia sp. and Trichoderma harzianum were isolated from Parthenium infested soil of Coimbatore district of Tamil Nadu. Spore suspension as well as culture filtrates of F. oxysporum and F. monilifonne were highly pathogenic to the weed and its seed germination and their pre-emergence and post-emergence applications at 5% level resulted in complete inhibition of seed germination and 100% wilt incidence, respectively. T. harzianum was highly pathogenic to the Parthenium seeds only but not to the established weed.