Direct Tissue Blotting for Detection of Tomato Spotted Wilt Virus in Impatiens. H. T. Hsu, Microbiologist, Agricultural Research Service, U.S. Department of Agriculture, Florist and Nursery Crops Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705. R. H. Lawson, Research Plant Pathologist, Agricultural Research Service, U.S. Department of Agriculture, Florist and Nursery Crops Laboratory, Beltsville Agricultural Research Center, Beltsville, MD 20705. Plant Dis. 75:292-295. Accepted for publication 13 September 1990. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1991. DOI: 10.1094/PD-75-0292.

Direct tissue blotting for detection of tomato spotted wilt virus (TSWV) was compared with enzyme-linked immunosorbent assay (ELISA) and a dot-blot immunoassay (DBIA). TSWV was readily detected in tissue blots of infected Nicotiana benthamiana leaves. When biotinylated mouse monoclonal antibodies were used, DBIA was nearly eight times more sensitive than ELISA for detection of TSWV in extracts from infected N. benthamiana leaves. Leaf and stem samples from Eustoma (lisianthus) and several Impatiens plants showing viruslike symptoms tested positively by double-antibody sandwich ELISA and by direct tissue blottings. Asymptomatic leaves or stems from the same plants were negative in ELISA tests. Although tissue blots of asymptomatic leaves and stems were negative to the naked eye, positive reactions were observed when blots were examined at × 10–20 with a dissecting microscope.