18 BULLETIN 1146, U. S. DEPARTMENT OF AGRICULTURE. 
the tubers from copper-sprayed plants were: 10-10-50 spray, 17.9 
per cent solids and 0.38 per cent nitrogen; 5-5—50 spray, 18.5 per cent 
_ solids and 0.34 per cent nitrogen; 24-24-50 spray, 20.1 per cent solids 
and 0.33 per cent nitrogen. The check tubers contained 18.3 per cent 
solids and 0.33’ per cent nitrogen. The tubers from the plots receiy- 
ing the 23-24-50 spray were highest, and those from the 10-10-50- 
sprayed plots were lowest in solids. 
These results suggest the possibility that a certain proportion of 
copper in a spray gives the maximum-stimulating effect in this local- 
ity and that a spray containing a greater proportion of copper may 
have a toxic rather than a stimulating effect. Tubers grown at 
Arlington Experimental Farm in 1920 from vines that were sprayed 
with a 10-10-50 Bordeaux spray (p. 18) seemed to have no advan- 
tages over the tubers from plants sprayed with a 44-50 Bordeaux. 
It is, of course, probable that the stimulating effect of the copper 
varies with the climatic conditions, variety of potatoes used, etc. 
Tubers from vines in New Jersey sprayed with a 5—5-50 spray eight 
times during the season were compared with tubers from vines 
sprayed only four times with Bordeaux spray of the same strength. 
The average data for four sets were 18.6 per cent of solids and 0.37 
per cent of nitrogen in the tubers from vines sprayed eight times and 
19.1 per cent of solids and 0.35 per cent of nitrogen for the tubers 
from vines sprayed only four times. These variations are small and 
may not be due to the differences in the spray applications. These 
data also indicate that too much copper may have reached the vines 
by the eight applications, whereas the amount of copper present in 
the four applications was nearer the quantity required to give the 
best protective effect or a maximum stimulation to the plants. 
INFLUENCE OF ENVIRONMENT ON COMPOSITION OF TUBERS. 
The following data were obtained during the 1919 season. Early 
Rose tubers grown in Connecticut contained 21.59 per cent solids and 
0.38 per cent nitrogen and the same variety grown at Arlington Ex- 
perimental Farm contained 15.83 per cent solids and 0.33 per cent 
nitrogen. Irish Cobbler tubers grown in Connecticut contained 22.28 
per cent solids and 0.43 per cent nitrogen, while the same variety 
grown at Arlington Experimental Farm contained 18.57 per cent 
solids and 0.36 per cent nitrogen. Dibble Russets from New York 
contained 25.38 per cent solids and 0.39 per cent nitrogen and thesame 
variety grown at Mt. Carmel, Conn., contained 21.24 per cent solids 
and 0.380 per cent nitrogen. Early Ohio tubers from Minnesota con- 
tained 22.79 per cent solids and 0.48 per cent nitrogen and the same 
variety from Connecticut, 20.52 per cent solids and 0.48 per cent 
nitrogen. These results again suggest that the composition of the 
tubers is infiuenced by the environment. 
Although these tubers were not grown from the same stock, the 
results in each case seem to indicate that a northern tuber is higher in 
solids than asoutherntuber. Thismay explain why a northern grown 
potato is a better seed potato than one grown in the South. The data 
also show that there is a decided variation in the percentage of 
solids in tubers of different varieties grown in the same locality. 
In this connection it is interesting to recall the findings of LeClere 
and Yoder (27) who, working with wheat in four different parts 
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