Datura spp. are medical herbs used as raw material in products such as pain-killers. Since September, 2012, we have investigated diseases of the medical herbs in the Tokyo Metropolitan Medicinal Plant Garden and found leaf spots on Datura inoxia and D. metel. On the spots, Alternaria crassa was abundantly observed. In this study we confirmed the pathogenicity of A. crassa to three Datura species (D. stramonium, D. metel and D. inoxia) and proposed the name of leaf spot (Japanese name: rinmon-byo) for the diseases.
