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Disease Note.

Tomato Spotted Wilt Virus on Oncidium Orchids in Hawaii. J. S. Hu, Department of Plant Pathology, University of Hawaii, Honolulu 96822. M. Wang, S. Ferreira, and D. Ogata. Department of Plant Pathology, University of Hawaii, Honolulu 96822. Plant Dis. 76:426. Accepted for publication 24 October 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0426D.

Because Frankliniella occidentalis (Pergande) and F. palmi (Karmy) are common insect pests on commercial orchids in Hawaii and are important vectors of Tomato spotted wilt virus (TSWV) on many crops, we tested orchid samples for TSWVin an orchid virus survey. Recently, TSWV-infected Oncidium orchids showing symptoms ranging from chlorotic ring spots to necrotic lesions 1-2 cm in diameter were found in a nursery in Hawaii. The plants were about 4 yr old and were being grown adjacent to chrysanthemums infected with the TSWV lettuce strain. This virus was detected from the ring spots and lesions with an antibody specific to TSWV lettuce strain in enzyme-linked immunosorbent assay (ELISA). The TSWV infection was localized, and samples from symptomless areas of infected leaves and new growth of infected plants were virus-free. Root samples from infected plants were also TSWV-free. At this one locaction, 50-100% of the Oncidium plants were infected with TSWV; healthy Oncidium control plants elicited no ELISA reaction. No flower symptoms were observed. TSWV impatiens strain, cymbidium mosaic virus, odontoglossum ringspot virus, and potyviruses were not found in the infected orchids. Approximately 2,500 orchid samples collected from 23 other farms and nurseries in Hawaii were all TSWV-free.

Reference: (1) M. Wang and D. Gonsalves. Plant Dis. 74:154,1990.