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Manganese Effect on the Local Lesion Symptom of Potato Spindle Tuber ‘Virus’ in Scopolia sinensis. R. P. Singh, Research Scientist, Agricultural Canada Research Station, Fredericton, New Brunswick; C. R. Lee(2), and M. C. Clark(3). (2)(3)Research Scientists, Agriculture Canada Research Station, Fredericton, New Brunswick, (2)Present address: Dept. of the Army, Waterways Experiment Station, Vicksburg, Mississippi 39180. Phytopathology 64:1015-1018. Accepted for publication 22 February 1974. DOI: 10.1094/Phyto-64-1015.

The influence of manganese on the development of local lesions in Scopolia sinensis was followed in plants inoculated with the potato spindle tuber ‘virus’ and maintained in sand culture at levels of Mn which varied from 0 to 18 µg/ml. Optimum expression of symptoms occurred on leaves which contained 1,900 µg Mn/g leaf tissue at a Mn/Fe ratio of 27. Over the shorter periods of lesion development, the effect of Mn at this concn in the leaf tissue was to produce a greater number of lesions in the upper leaves of S. sinensis than in the lower ones. Magnesium was without effect on the enhancement of symptom expression by Mn in this local-lesion indicator plant. These and other considerations suggest that higher-than-normal Mn levels are required for the replication of potato spindle tuber RNA in the tissues of its various hosts.