DETECTION OF CYMBIDIUM MOSAIC-VIRUS, ODONTOGLOSSUM RINGSPOT VIRUS, TOMATO SPOTTED WILT VIRUS, AND POTYVIRUSES INFECTING ORCHIDS IN HAWAII

Approximately 3,600 orchid plants representing 44 genera from three orchid collections, 22 commercial farms, and six nurseries on the islands of Oahu and Hawaii were tested for Cymbidium mosaic virus (CyMV), Odontoglossum ringspot virus (ORSV), tomato spotted wilt virus (TSWV), and potyviruses with enzyme-linked immunosorbent assay (ELISA). CyMV was detected in 59 samples and ORSV was detected in 23 samples, which represented 61 and 25% of the 44 genera surveyed, respectively. Double infection with both viruses occurred in 20 samples, representing 20% of the genera. CyMV and ORSV were detected in 29 and seven of the 31 sites surveyed, respectively. When 330 cloned orchid samples were tested, CyMV was detected in 45% and ORSV in 9% of the clones. Most commercial Dendrobium orchids grown in Hawaii are seed-propagated hybrids produced by the Horticulture Department at the University of Hawaii (UH). Only 4% of the 758 UH Dendrobium hybrids less than three years old were infected by CyMV. Of 2,381 UH Dendrobium hybrids more than 3 yr old, CyMV was detected in 94% of the samples from some farms, but only 2% from other farms. ORSV was not identified from any commercially grown UH Dendrobium hybrids. TSWV-infected Oncidium orchids, found in only one nursery in Hawaii, exhibited symptoms ranging from chlorotic ring spots to necrotic lesions 1-2 cm in diameter. The TSWV infection was localized in the ring spots and lesions. Dendrobium mosaic potyvirus was detected in Dendrobium superbum.