Disease Note.

Tomato Spotted Wilt Virus on Chrysanthemum in Argentina. E. Dal Bo, Instituto de Bioquimica y Biologia Molecular, Fac. de Cs. Exactas, UNLP, Calles 47 y 115 (1900) La Plata . L. Ronco and A. M. Alippi, CStedra de Fitopatologia, Fac. de Cs. Agrarias y Forestales, UNLP, Calles 60 y 119 (1900) La Plata, and R. Fernandez, UEEA Gran Buenos Aires, INTA, Argentina. Plant Dis. 79:538. Accepted for publication 10 April 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/PD-79-0538E.

Plants of Chrysanthemum x morifolium Ramat, showing chlorotic ringspots, line patterns and necrosis on leaves, stunting, necrotic streaks on the stem, pith necrosis, and flower distortion were seen during the 1993-94 summer in commercial greenhouses near La Plata (Buenos Aires). The most affected cultivars were Palisade and Southern Sun. In nearly 60% of the greenhouses 5 to 70% of the plants of the two cultivars were symptomatic. No pathogenic fungi and bacteria were associated with symptomatic plants. Tomato spotted wilt virus (TSWV) was identified by inoculation to indicator hosts (systemic infection on Nicotiana rustica L. and N. glutinosa L., and local lesions on Petunia ? hybrida Hort. Vilm.-Andr. and Chenopodium quinoa Willd.) and by immunobind-ing assays on prints of rolled leaves and stems using a monoclonal antibody specific for TSWV (MAB17B4) (1). The virus was detected more clearly in stem than in leaf prints of the same plant. Spherical particles with a diameter of 80 to 100 nm were observed in negatively stained preparations by electron microscopy. This first outbreak of TSWV on chrysanthemum in Argentina appears together with the first record of Frankliniella occidentalis Pergande in the country (2).