An attempt has been made to identify and study the growth pattern of Alternaria porri that causes purple blotch of onions. Czapek-Dox medium amended with nutrients like lactose, urea, diammonium hydrogen orthophosphate, ammonium sulfate and pH 5.0 supported good growth of the pathogen. Toxic potential of the culture filtrates of the strain was assessed in terms of phytotoxicity against seed germination as well as seedling growth of onions and antibacterial activity against selected bacteria. Mancozeb and extracts from the plant species, Mentha arvensis were effective in controlling the growth of A. porri.
