Survey of New South Wales Potato Crops for Potato Spindle Tuber Viroid with Use of a ³²P-DNA Probe. M. W. Schwinghamer, Visiting Scientist, N.S.W. Department of Agriculture, P.M.B. 10, Rydalmere, New South Wales 2116. G. R. Scott, Former Research Horticulturist, Agricultural Research and Advisory Station, Glen Innes, New South Wales 2370. Plant Dis. 70:774-776. Accepted for publication 9 January 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-774.

The dot-blot membrane hybridization assay, which employs a ³²P-labeled complementary deoxyribonucleic acid probe, was tested as a means of detecting potato spindle tuber viroid (PSTV) in bulked leaf samples from potato (Solanum tuberosum). Levels as low as one infected leaf disk in 400 were detected. Inoculating tomato (Lycopersicon esculentum) plants and assaying these with the probe was less reliable and no more sensitive. The direct assay was used in a statewide survey of certified seed potato crops, and it was concluded that none of the 18,900 plants sampled was infected with PSTV.