The cause of purple-top of potatoes, as indicated by a study of its distribution within fields

Summary

From a statistical study of the distribution of purple-top within tuber-unit plantings it is clear that the cause of purple-top may operate variously over a field but with similar freedom along and across rows of potatoes. There is, further, certainly no tendency for one plant to be infected as a co-member of a tuber-unit has purple-top; hence the condition cannot be simply transmitted from a plant to its neighbor. There is an uncertain suggestion, to the contrary, that a regular proportion of plants in each tuber-unit tend to purple-top, as might be the case if structure of the mother tuber, for each unit, were involved.