In 1997, we observed high incidence of severe disease symptoms in a plantation of St. John's-wort (Hypericum perforatum L.) that has been cultivated as a medicinal plant in Hungary. Symptoms were characterized by brown, 2- to 15-mm-diameter, sunken lesions that girdled the stems and, when occurring near the base, killed the plants. Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. was consistently isolated from lesions. Acervuli containing conidia and dark setae emerged from the lesions. Perithecia of the teleomorph Glomerella cingulata (Stoneman) Spauld. & H. Schrenk also appeared on stems. Plants were inoculated with conidial suspension of the fungus (2 × 107/ml), then incubated in a moist chamber for 24 h, and subsequently transferred to the greenhouse. The first symptoms appeared on stems and leaves 7 days after inoculation. Chlorotic spots grew into circular and buff-colored lesions that coalesced and then desiccated. The fungus caused severe defoliation and plant death within 2 weeks. Koch's postulates was completed by consistently reisolating the pathogen from inoculated plants. This disease on St. John's-wort has not previously been reported in Hungary. However, an anthracnose disease caused by Glomerella cingulata (Stoneman) Spauld. & H. Schrenk var. migrans Wollenweber (Gloeosporium orbiculare Berk. & Mont.) was reported in Germany in 1949 (1).
Reference: (1) H. W. Wollenweber and H. Hochapfel. Z. Parasitenkd. 14:181, 1949.
