A leaf spot disease on sweet basil (Ocimum basilicum L.) was observed in Chiba Prefecture in 1997. The lesions were amphigenous, circular to irregular, hygrophanous, dark brown.
Stromata were amphigenous, composed of a few brown cells. Conidia with a thickened truncate base, filiform to cylindrical,
hyaline, were produced from conidiophores with thickened conidial scars. These morphological characteristics agreed with those
of Cercospora guatemalensis Mueller et Chupp. This species was new to Japan. The symptoms appeared 10 days after inoculation and the inoculated fungus
was re-isolated. Artificial sporulation and detection from commercial seeds were not successful.