The data presented confirm the opinion that the healthy hills adjoined by leaf roll plants on one or on both sides, compensate,
in part, for the low yield of the leaf roll plants.
The gain in yield of a healthy plant adjoined on both sides by leaf roll plants is approximately double the gain of such plants
adjoined by a leaf roll plant on one side only.
The tables presented show the average yields of the plants in the different classes in these fields and also the relative
yields of potatoes with various percentages of leaf roll in them. The same results are also expressed in the form of equations
which can be used to estimate the yielding capacity of a variety, strain or plot, even though, when grown, it has in it a
known percentage of leaf roll.
The following research assistants participated in collecting the data presented in this paper.—C. S. Tuthill, Dr. P. Decker,
R. E. Wilkinson, C. A. Thomas and W. F. Mai.