First report of Alternaria sp. PMK1: causative agent of leaf spot disease on parthenium weed

Congress grass, Parthenium hysterophorus L. (Asteraceae, tribe Heliantheae), is an erect and much branched annual or ephemeral herb, known as a pest for environmental, medical and agricultural reasons. Survey of fungal pathogens of P. hysterophorus was conducted in Kurukshetra and its adjoining areas, Haryana, India. A leaf spot pathogen Alternaria sp. PMK1 was isolated. Koch's postulates were performed and proved that this isolate was pathogenic to this weed. This is the first report of this pathogen causing leaf spot on parthenium weed.