septoriaPronunciation: /sɛpˈtɔːrɪə/Definition of septoria noun [mass noun] a fungus of a genus that includes many kinds that cause diseases in plants. Genus Septoria, subdivision Deuteromycotina leaf spot disease caused by a septoria fungus. Origin:modern Latin, from Latin septum (see septum)septoria in other Oxford dictionaries Definition of septoria in the US English dictionary