216 
Journal of Agricultural Research 
Vol. VII, No. s 
July 3 in two cases—but otherwise the procedure was practically the 
same as that generally followed in northern Maine, and the plants 
received, so far as possible, the same cultural treatment as potatoes 
growing under field conditions. Owing to the late planting and early 
frost, the plants had a rather short growing season; and although not 
harvested until October 15, the tubers were small and in most cases 
immature. However, the conditions were sufficiently favorable to per¬ 
mit the development of the disease, which was the primary object of the 
experiment, and the results from this standpoint are given in Table III. 
Table III .—Results of planting potatoes infected with Spongospora suhterranea at 
Presque Isle , Me ., in soil from the plots in which diseased seed had been grown in various 
States 
Source of soil. 
Number 
Number 
of sound 
tubers. 
Tubers infected — 
of hills. 
Number. 
Per cent. 
Diamond Springs, Va. 
I 
3 
2 
Amherst, Mass. 
3 
2 
0 
15 
0 
? 
40. OO 
16. 66 
Q 
College Park, ■ Md. 
0 
0 
Morgantown, W.Va. 
A 
V 
12 
A 
25. 00 
New Brunswick, N. J. 
T- 
2 
II 
T- 
3 
1 
Unknown a . 
2 
IO 
2 1 • 40 
9* 00 
0 
Geneva, N. Y. 
I 
8 
0 
Mount Carmel, Conn... 
3 
2 
16 
I A 
2 
11. 11 
6. 66 
27. 27 
0 
Gainesville, Fla. 
1 
Ithaca, N. Y. 
2 
- Li r 
8 
3 
0 
■Newark, Del. 
2 
*5 
7 
8 
Unknown a . 
1 
0 
0 
Presque Isle, Me. 
2 
2 
20. 00 
a In both of these cases the tags showing the source had been lost en route, which made it impossible 
to say definitely whence they came. 
From the fact that Spongospora suhterranea developed in 8 of the 12 
soils tested, as shown by Table III, it seems safe to assume that it would 
have resulted in all had it been possible to have more soil and to make 
conditions more favorable for the growth and development of the po¬ 
tato plant. However, the experiment developed the important fact 
that powdery-scab was produced under Maine conditions in soils in 
which in their native States the disease was not produced. 
This raised the question as to whether soil from infected sections 
will produce an infected crop when transplanted into a noninfected sec¬ 
tion. To test this, two lots of soil of 200 pounds each were collected 
from a field in northern Maine that produced an infected crop in 1914, 
and one was shipped to Washington, D. C., and was used in growing 
potatoes in the green house, and the other to Norfolk, Va., where it 
was .placed in large iron cylinders sunk into the ground at the edge of a 
potato field and planted with clean tubers. The former produced a 
crop that became badly infected with powdery-scab, while the plants 
produced in the latter developed unusually well and the progeny re- 
