30 
BULLETIN 195 ; XL S. DEPARTMENT OF AGRICULTURE. 
were remarkably uniform in size and there could, therefore, have 
been little difference in the size of the seed pieces used. Any varia- 
tion, therefore, which occurred between the plants of the various 
tubers which were planted would seem to be due to some inherent 
tendency in the tuber itself. The remarkable dissimilarity between 
the growing plants of the individual units of a variety planted con- 
tiguously in the row was so surprising that some three dozen units 
were photographed and when these were harvested the tubers were 
also photographed. It was found that the divergency in yield was 
just as great as in the size and vigor of the plants. In 1912 five 
units Y\ r ere planted from both the strong and the weak plants, and 
it was found in practically every instance that the low-yielding 1911 
plants gave poor germination, a feeble vine growth, and a still lower 
yield than in 1912 (PI. XV). Table VI gives the data obtained 
during 1911 and 1912 from 12 strong and weak tuber-unit plants of 
well-known commercial varieties. 
Table VI. — Potato yields from strong and weak tuber-unit plants in 1911 and 1912. 
[Weight of tuber yields in pounds.] 
1 
§5 
2* 
< 
Variety. 
Strong plants, 
1911. 
Strong plants, 
1912. 
Weak plants, 
1911. 
Weak plants, 
1912. 
c/5 
® 
a 
£ 
8 
o 
Eh 
<8 
g 
o 
3 
o 
Eh 
1 
"3 

Eh 
»5 
1 
■a 
"0 
Eh 
4245 
4235 
4972 
Beauty of Hebron 
Carman No. 1 
Gold Coin 
4.0 
2.6 
3.4 
3.8 
4.3 
3.8 
2.6 
2.8 
3.9 
4.4 
1.5 
3.1 
1.5 
1.6 
2.0 
1.3 
.3 
.3 
2.0 
1.3 
1.4 
1.4 
2.7 
1-0 
5.5 
4.2 
5.4 
5.1 
4.6 
4.1 
4.6 
4.1 
5.3 
5.8 
4.2 
4.1 
2.9 
4.4 
3.0 
2.0 
4.8 
1.7 
2.9 
2.1 
3.94 
4.1 
3.9 
2.7 
1.2 
.8 
.54 
.6 
.9 
2.0 
.85 
.4 
1.1 
1.7 
.64 
.64 
4.1 
5.2 
3.54 
2.6 
5.7 
3.7 
3.75 
2.5 
5.04 
5.8 
4.54 
3.34 
0.4 
'"".'9 
"l'.'o 
..... 
0.9 
.8 
1.1 
1.1 
.8 
1.0 
.6 
.3 
.5 
.9 
1.3 
.1 
1.3 
.8 
1.1 
1.1 
.8 
1.9 
.6 
1.8 
.5 
.9 
1.5 
.1 
0.7 
..„. 
.14 
"'."25 
"."l2 
'".12 
.04 
1.0 
.14 
.25 
.17 
.04 
.38 
.02 
.29 
.03 
.08 
.33 
1.7 
.14 
.65 
4968 
8686 
4970 
5036 
Green Mountain 
do 
Irish Cobbler 
Keeper 
.31 
.04 
.63 
.02 
6153 
5460 
McCormick 
.41 
.03 
5462 
5480 
do 
Rural Blush 
.2 
.37 
6690 
Total 
Average 
40.2 
3.35 
16.8 
1.4 
57.0 
4. 75 
38.44 
3.2 
11.37 
.95 
49.81 
4.15 
3.0 
.25 
9.4 
.78 
12.4 
1.03 
1.77 
.15 
2.73 
.23 
4.50 
.38 
Two-year tuber-unit average: 
Strong plants — 3.28 pounds primes; 1.18 pounds culls; total, 4.46 pounds. 
Weak plants— 0.20 pound primes; 0.51 pound culls; total, 0.71 pound. 
Gain in primes in favor of strong plants, 1,540 per cent; total gain in favor of strong plants, 528.2 per cent. 
The average yield of merchantable or prime tubers from the strong 
plants was 3.35 pounds in 1911, with 1.4 pounds of culls, while the 
yield from the weak plants was 0.25 and 0.78 pound, respectively. 
In 1912 the yields were 3.2 pounds of primes and 0.95 pound of culls 
from the strong plants and 0.15 and 0.23 pound, respectively, from the 
weak plants. The average production for 1911 and 1912 was 3.28 
pounds of primes and 1.18 pounds of culls from the strong plants and 
0.20 pound of primes and 0.51 pound of culls from the weak plants. 
These yields represent a gain in primes of over 1,500 per cent in favor of 
