In the spring and summer of 1998, a severe virus-like disease consisting of chlorotic mottle on leaves, yellowing, and stunting was observed at the Giardino delle Erbe of Casola-Valsenio (Emila-Romagna region, northern Italy). Most of the symptomatic plants were infected with a filamentous virus that was not identified. Moreover, one thyme plant showing yellow leaves was also found infected by an isometric virus, the identity of which was established by the following host reactions and serological assay. It was mechanically transmitted to 33 species belonging to 11 botanical families. All the Chenopodiaceae (Chenopodium amaranticolor Coste et Reyn., C. murale L., C. foliosum Ash., and C. quinoa Willd.) tested showed local and systemic symptoms in 3 to 4 days; among Leguminosae, broad bean (Vicia faba L.) showed necrotic local lesions and wilt. Virus particles reacted in protein A sandwich-enzyme-linked immunosorbent assay with the antiserum to Broad bean wilt virus (BBWV), serotype I (supplied from the Istituto di Fitovirologia Applicata, CNR, Turin, Italy). BBWV in the field was in all probability transmitted to thyme by aphids from weeds and/or other medicinal and aromatic species cultivated in the same herb garden, all recently shown to be hosts for BBWV: Polygonum fagopyrum L., Hedisarum coronarium L., Borago officinalis L., Phytolacca Americana L., Digitalis lanata Ehrh., and D. purpurea L. (1). This is the first report of BBWV in T. vulgaris and demonstrates that it is more prevalent in Italy than previously reported.
References: (1) C. Rubies-Autonell and M. G. Bellardi. 1999. 7th International Plant Virus Epidemiology Symposium, Aguadulce, Spain.