Abstract
ABSTRACT: One of the most aggressive invasive weeds, Parthenium hysterophorus (Asteraceae) is generating serious difficulties for the environment, economy, and livestock in India and other parts of the world. The present study was conducted to isolate and identify the fungal pathogens from the leaves of Parthenium weed and evaluate their cultural filtrates against the growth of the weed. Alternaria alternata was isolated from the infected Parthenium leaves by using standard isolation techniques utilizing potato dextrose agar (PDA), during an extensive search for natural enemies of P. hysterophorus. After applying Koch's postulates and leaf bioassay, it was discovered that A. alternata was found pathogenic and can be used as biocontrol agent of the weed. Seed germination bioassay was performed to check the herbicidal potential of A. alternata metabolites against Parthenium plant. The fungal pathogen's metabolites caused severe harm to the leaves and seeds of P. hysterophorus. This research aims to explore the biological control efficacy of isolated fungus A. alternata to inhibit Parthenium growth.