24 BULLETIN 1146, U. S. DEPARTMENT OF AGRICULTURE. 
was applied four times, show that the tubers were lower in solids in 
the former than in the latter case, suggesting again that too much 
copper may have reached the plant for the best results in the absence 
of any late blight. 
Tubers from several varieties of potatoes grown in a northern State 
were higher in solids than tubers of the same varieties grown in a 
State farther south. 
A larger yield of potatoes was secured from copper-sprayed than 
from check or noncopper-sprayed vines. Late blight (Phytophthora 
infestans) is eliminated as a necessary factor in the case. 
When a lime spray containing no copper was used at Arlington Ex- 
perimental Farm, Va., the yields of tubers were decreased. Picker- 
ing-limewater spray and a barium-water spray gave practically the 
same increase in yield and in solids of the tubers as a Bordeaux spray. 
The copper in the spray seems to be the essential factor. 
LITERATURE CITED. - 
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(4) Bascock, D. C. 
Potato diseases. Ohio Agr. Exp. Sta. Bull. 319 (1917) : 121-136. 
(5) BALL, EB. D. 
The potato leafhopper and the hopperburn. Phytopath., 9 (1919): 
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(6) CHUARD, and PoRCcHET, E. 
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(7) CLARK, W. M., and Luss, H. A. 
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applications in bacteriology. J. Bact., 2 (1917): 1-84. 
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(1915) : 421-487. 
(9) Cook, F. C. 
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(11) 
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(12) DIEULAFAIT. 
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(13) Duptry, J. E., and Witson, H. F. 
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