Reactions of Tuber-Bearing Solanum Species to Infection with Potato Spindle Tuber Viroid. R. P. Singh, Research Scientist, Agriculture Canada, Research Station, Fredericton, New Brunswick, E3B 4Z7, Canada. S. A. Slack, Associate Professor, Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 68:784-787. Accepted for publication 12 March 1984. Copyright 1984 Department of Agriculture, Government of Canada. DOI: 10.1094/PD-68-784.

A total of 555 plant introductions belonging to 81 tuber-bearing Solanum species were evaluated in greenhouse or field tests for their reactions to mild and severe strains of the potato spindle tuber viroid (PSTV). Plants tolerant to PSTV were found, but none were immune. Although most plants of all species displayed diagnostic symptoms, symptomless plants were observed for 38 species. None of the inoculated plants for 17 of the 38 introductions developed symptoms. Primary symptoms consisted of stunting of whole plants; reduced leaf size; and necrosis of petioles, leaf veins, and stems. Selection and clonal propagation before inoculation of plants that develop diagnostic symptoms when inoculated with either mild or severe strains of PSTV may be useful for bioassay purposes.