Archivio Journal of Plant Pathology

Abstract:

Starting from July 2014, symptoms of a previously unreported blight were observed on leaves, stems and inflorescences of Salvia oxyphora, family Labiatae, growing in a private garden near the city of Biella (northern Italy). Infections started from fallen flowers adhering to the leaves. A soft, grey mycelium developed on symptomatic stem tissues, from which a fungus was isolated that, on potato dextrose agar, produced abundant mycelium with branched conidiophores and enlarged apical cells. Conidia were unicellular, light ash-colored, ovoid, and measured 6.3- 14.8×5.3-9.8 (average 9.8×7.1) μm. These morphological features are typical of Botrytis cinerea (Ellis, 1971). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4, and sequenced (GenBank accession No. KP686392). BLAST analysis (Altschul et al., 1997) of the amplified 497 bp sequence, showed a 99% similarity with the sequence of Botryotinia fuckeliana isolate KF667540. Pathogenicity tests were performed by inoculating leaves of three healthy S. oxyphora plants with mycelial disks from PDA cultures. Controls were inoculated with sterile PDA disks. Plants were covered with plastic bags. The first foliar necrotic symptoms developed three days after the experimental inoculation and seven days afterwards the symptoms were similar to those observed in the field. B. cinerea was consistently re-isolated from symptomatic leaves, whereas controls remained healthy. This is the first report of B. cinerea on S. oxyphora in Italy and in the world.