A LEAF SPOT CAUSED BY STAGONOSPOROPSIS TRACHELII ON CAMPANULA TRACHELIUM IN ITALY
A. Garibaldi, D. Bertetti, S. Matić, M.L. Gullino
Campanula trachelium (family Campanulaceae), is widely present in the Italian flora and it is used in gardens for borders. In September 2016, a foliar disease was observed on 10-month-old plants grown in a garden located in the Biella province (northern Italy). Symptoms consisted in extensive chlorosis followed by dark brown, irregular, necrotic spots that extended onto and dried the affected leaves. A fungus was consistently isolated from affected leaf tissues. On oatmeal agar (OA), colonies were first whitish, then greenish olivaceous in the centre and produced spheroid pycnidia 81-287 (mean 138) µm in diameter that contained conidia elliptical to cylindrical in shape, non-septate measuring 3.3-6.7×1.1-2.9 (mean 4.4×1.8) µm in size. The internal transcribed spacer (ITS) of the isolate DB16SET27 was amplified using the primers ITS1/ITS4 and sequenced (GenBank accession No. KY704321). BLAST analysis (Altschul et al., 1997) showed 99% homology with the sequence of Stagonosporopsis trachelii KP136795. For pathogenicity tests mycelial PDA plugs (8 mm in diameter) of the isolate DB16SET27 were applied onto leaves of three 3-month-old plants of C. trachelium. Three control plants were treated with PDA dishes only. All the plants were maintained in a humid chamber at a temperatures ranging from 20.7 to 22.5°C. Two days after the appositions of the PDA dishes, the first necrosis appeared around the inoculum. The same fungus used for inoculation was reisolated from affected leaves. Controls remained healthy. S. trachelii had already been reported on Campanula medium in Italy (Garibaldi et al., 2015), whereas this represents the first report to the same pathogen infecting C. trachelium in the same country.