Archivio Journal of Plant Pathology

Abstract:

During the summer and autumn 2015, symptoms of an unknown leaf blight were observed on fruit-scented sage (Salvia dorisiana), Labiatae family, cultivated in a private garden located in the Biella province (northern Italy). Brown necrosis with irregular margins developed on both leaf surfaces, on the apexes and along the borders. Sometime, a soft, grey mycelium grew on affected tissues. Fungal colonies isolated from leaves on potato dextrose agar (PDA) were typical of Botrytis cinerea (Ellis, 1971) and produced branched conidiophores and unicellular, ovoid conidia, measuring 7.8-14.5 × 6.4-9.0 (average: 10.8×7.5) μm. The Internal Transcribed Spacer (ITS) region of rDNA extracted from a pure culture was amplified using the primers ITS1/ITS4 (White et al., 1990), and sequenced (GenBank accession No. KU163301). BLAST analysis of the 456 bp amplicon had 100% homology with the sequence of B. cinerea (KR080287). To reproduce the field symptoms, one isolate was inoculated on healthy leaves of three S. dorisiana plants. Five leaves per plant were treated with mycelial disks obtained from a pure fungal culture, while three controls were exposed to sterile PDA. All plants were covered with plastic bags and maintained in a greenhouse at temperatures ranging from 15 to 23°C. Five days post inoculation , the first symptoms developed on inoculated leaves only. B. cinerea was reisolated from affected tissues, while controls remained healthy. This is the first report of B. cinerea on S. dorisiana in Italy, as well as in the world. The economic significance of this disease is limited at present, however its importance may expand due to the increasing use of S. dorisiana as a bedding plant.