Archivio Journal of Plant Pathology

Abstract:

Campanula medium, family Campanulaceae, is used in borders of gardens and as a cut flower. During the summer 2014, 12-month-old plants grown in a garden near Biella (Northern Italy) showed a severe foliar disease. Approximately 60% of about a hundred plants were affected. Symptoms were extensive chlorosis, followed by the appearance of brown, irregular spots on the leaves. Also stems were damaged, showing longitudinal necrosis. From affected leaves, on PDA, a fungus with a dark olive mycelium at maturity was consistently isolated on potato dextrose agar (PDA) plates. On oat agar (OA), colonies produced dark, spheroid to elongated pycnidia, 75-297 (mean 159) μm in diameter. These contained numerous cylindrical non-septate conidia, measuring 4.1-8.0×0.9-2.3 (mean 5.7×1.6) μm. The internal transcribed spacer (ITS) was amplified using the primers ITS1/ITS4 and sequenced (GenBank accession No. KP136795). BLAST analysis (Altschul et al., 1997) showed 99% homology with the sequence of Stagonosporopsis trachelii (GU237850). For pathogenicity tests a suspension of mycelial fragments was sprayed onto leaves of three healthy plants of C. medium. Three controls were inoculated with sterile water. Plants were covered with plastic bags. The first foliar lesions developed on leaves three days post inoculation. The fungus reisolated from leaf lesions was identical in morphology to the isolate used for inoculation. Controls remained healthy. This is the first report of S. trachelii on C. medium in Italy.