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Disease Detection and Losses

Potato Spindle Tuber Disease: Procedures for the Detection of Viroid RNA and Certification of Disease-Free Potato Tubers. T. J. Morris, Assistant Professor, Department of Biology, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3, Present address of senior author: Department of Plant Pathology, University of California, Berkeley 94720; E. M. Smith, Technical Advisor, Plant Protection Division, Production and Marketing Branch, Agriculture Canada, Fredericton, New Brunswick, Canada E3B 5A3. Phytopathology 67:145-150. Accepted for publication 21 May 1976. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-145.

Detection of viroid RNA in small quantities of potato spindle tuber viroid-infected potato and tomato terminal tip tissue has been used for rapid and reliable diagnosis of the disease. The method involved the extraction of cellular nucleic acids followed by electrophoretic analysis of the extracts on 5% polyacrylamide gels. Initial inoculation of tomato plants with extracts from potato terminal tip tissue and subsequent analysis of the inoculated tomatoes by the gel method allowed detection of one infected plant in a 250-plant test. Application of these procedures to a routine potato-indexing program is discussed in relation to the possibility of producing seed potatoes certified to be free of this disease.