﻿COPPER SPRAYS ON TTUSH POTATO TTTRKRS. 



19 



of the United States, concluded that environment rather than hered- 

 ity is the major factor in determining the physical and chemical 

 characteristics of the wheat crop. 



COPPER CONTENT OF VINES, STEMS, ROOTS, AND TUBERS OF SPRAYED AND UN- 

 SPRAYED PLANTS. 



Copper is widely distributed in nature. Apparently all plants 

 and animals contain small amounts of this metal. 



In 1816 Meissner (35) reported that copper was present in the ash 

 of various plants in small quantities. Dieulafait (12) in 1880 showed 

 that the amount of copper present in vegetation was largely de- 

 termined by the nature of the soil. 



Lehmann (28), in 1895 and 1896, estimated the copper in wheat, 

 rye, barley, oats, maize, buckwheat, potatoes, beans, linseed, apricots, 

 pears, breads, cocoa, and chocolate. He found that only in the 

 plants grown in soil relatively high in copper does any appreciable 

 amount of copper get into the plant. The species of plant is ap- 

 parently of less importance than the copper content of the soil in 

 determining the amount of copper found in the plant. In wheat 

 and buckwheat the copper was chiefly in the stems and leaves, 

 little being found in the fruits and seeds. Therefore a high copper 

 content in the soil does not necessarily mean that much copper is 

 present in the grain and seed. The form in which the copper exists 

 in plants is not known. Lehmann gives data showing that the 

 quantity of copper in any species of plant varies with the individuals 

 of the species, even when grown on the same soil in the same year, 

 and under similar conditions. 



MacDougal (34) examined microscopically and analyzed various 

 parts of a tree which had grown in copper-bearing soil. He found 

 metallic copper in relatively large quantities throughout the tissues, 

 indicating an absorption of copper by the tree over a period of years. 



Table 8. — Copper in tubers from copper-sprayed and noncopper-sprayed plants. 



[Parts per million.] 





Place grown. 



Copper in dry tubers from vines treated with '— 



Variety. 



Calcium 

 arsenate 

 (no cop- 

 per). 



Bordeaux 



spray. 



Picker- 

 ing spray. 



Lead 

 arsenate 

 (no cop- 

 per). 



Check 

 (no cop- 

 per). 





Arlington Experimental 



Farm, Va. 

 do 



8 



11 

 11 

 14 

 11 



11 



13 

 15 



16 

 14 



15 



9 



14 

 15 



13 







Irish Cobbler 







Do 



do 







Do 



. .do 



















11 

 10 

 10 





American Giant 





11 









1 9 

 10 

 10 

 11 



f 2g 

 \ 38 



8 

 10 











13 



Green Mountain 











9 



Magnum Bonum 











10 



Dibble Russet 



do 































10 



Average 











10 















1 All of the copper-sprayed plants received an arsenical spray as well. 

 i Sprayed twice. 

 3 Sprayed 6 times. 



