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Eradication of Potato Spindle Tuber Virus by Thermotherapy and Axillary Bud Culture. Richard Stace- Smith, Plant Pathologist, Canada Agriculture Research Station, 6660 N.W. Marine Drive, Vancouver 8, British Columbia, Canada; Frances C. Mellor, Plant Pathologist, Canada Agriculture Research Station, 6660 N.W. Marine Drive, Vancouver 8, British Columbia, Canada. Phytopathology 60:1857-1858. DOI: 10.1094/Phyto-60-1857.

Potato spindle tuber virus (PSTV) was eradicated from infected potato (Solanum tuberosum) by nutrient culture of axillary buds excised from heat-treated plants. Plants infected with severe PSTV were subjected to air temperatures which alternated daily from 33 to 36 C. Fluorescent lights provided a 16-hr photoperiod. At intervals during treatment, axillary buds 0.5-1.0 mm long were excised for nutrient culture. Severe PSTV survived in 62 of the 66 plantlets that developed. The remaining 4 plantlets showed no symptoms, but indexing revealed that all were infected with mild PSTV. Rooted tip cuttings of 1 plant infected with mild PSTV were again subjected to the combined treatment of thermotherapy and nutrient culture of axillary buds. Mild PSTV survived in 242 of the 248 plantlets that developed. In the remaining 6 plantlets, PSTV could not be detected, either by direct inoculation to tomato (Lycopersicon esculentum) or by the challenge-inoculation technique. The low incidence of virus-free plantlets may be associated with the fact that PSTV appears to be free nucleic acid with no protein coat.