﻿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 t {Phytophth&m 

 hifestans) is eliminated as a necessary factor in the case. 



When a lime spray containing no copper was used at Arlington Ex- 

 perimental Farm, \ r a.. 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. 



(1) Amos, A. 



The effect of fungicides upon the assimilation of carbon dioxide by 

 green leaves. J. Agr. Sci., 2 (1907) : 257-266. 



(2) Appleman. C. O. 



Changes in potatoes during storage. Md. Agr. Exp. Sta. Bull. 167 

 (1912) : 327-334. 



(3) Assoc. Official Agk. Chemists. 



Official and tentative methods of analysis, 417 pp. Washington, D. C, 

 1920. 



(4) Babcock, D. C. 



Potato diseases. Ohio Agr. Exp. Sta. Bull. 319 (1917) : 121-136. 



(5) Ball, E. D. 



The potato leafhopper and the hopperburn. Phytopath., 9 (1919) : 

 291-293. 



(6) Chuard, and Porchet, E. 



L'action des sels de cuivre sur les vegetaux. Arch. sci. phys. nat, l't 

 (1902) : 502-5. 



(7) Clark, W. M., and Lubs, H. A. 



The colorimetric determination of hydrogen ion concentration and its 

 applications in bacteriology. J. Bact, 2 (1917) : 1-34. 



(8) Clinton, G. P. 



Report of the botanist for 1915. Conn. Agr. Exp. Sta. 39th Ann. Rpt. 

 (1915) : 421-487. 



(9) Cook, F. C. 



Pickering sprays. U. S. Dept. Agr. Bull. 866 (1920) : 47 pp. 

 (10) 



(11) 



Composition of tubers, skins, and sprouts of three varieties of potatoes. 

 J. Agr. Research, 20 (1921) : 623-635. 



Absorption of copper from the soil by potato plants. J. Agr. Research, 

 22 (1921) : 281-287. 



(12) DlEULAFAIT. 



Sur la presence normale du cuivre dans les plantes qui vivent sur les 

 roches de la formation primordiale. Compt. rend., 90 (1880) : 

 703-705. 



(13) Dudley, J. E., and Wilson, H. F. 



Comhat potato leafhopper with Bordeaux. Wis. Agr. Exp. Sta. Bull. 

 334 (1921) : 31 pp. 



(14) Duggar, B. M., and Cooley, J. S. 



The effects of surface films on the rate of transpiration : Experiments 

 with potted potatoes. Ann. Mo. Bot. Gard., 1 (1914) : 351-356. 



(15) Edgerton, C. W. 



Delayed ripening of tomatoes caused by spraying with Bordeaux mix- 

 ture. La. Agr. Exp. Sta. Bull. 164 (1918) : 1-16. 



