154 Journal of Agricultural Research vol. xxi, NO. 3 



manganese content of the soil. Dement jew (4) discusses the question of 

 whether chloroses corrected by iron are really cases of iron hunger. 



The literature on the chlorosis of conifers is relatively small. Sorauer 

 (23) has reported chlorosis in Thuja occidentalis in Europe, and Schmuzi- 

 ger (21) and Dafert and Kornauth (j) have noted chlorosis in spruce, 

 without attempting to connect it with causal factors. Schmuziger re- 

 ports, as do other observers on angiosperms, that the chlorotic leaves con- 

 tained plastids which became green when the leaves recovered. Neger 

 (16) has described in more detail a chlorosis of spruce in a cold autumn 

 in which the yellow leaves or parts of them were found to contain much 

 more starch than the green leaves or their green bases with yellow tips. 

 He rather vaguely connects both current low temperature and the drouth 

 of the preceding winter with the various phenomena observed. 



Contejean (j) lists Scotch pine (Pinus sylvestris) as somewhat calcifuge, 

 and makes the general statement that excess lime accompanied by lack 

 of iron, or "encore plus" lack of potassium, results in chlorosis of calcifuge 

 plants. He, however, makes no specific mention of chlorosis in any 

 conifer. Fliche and Grandeau (5) attribute the calcifuge tendencies of 

 P. sylvestris to the physical rather than the chemical qualities of lime 

 soils. They find Austrian pine (P. austriaca), P. halepensis, and Abies 

 pectinata doing well on strongly calcareous soils, but they find P. pinaster 

 making a poor growth in plantations on calcareous soil in all cases ob- 

 served and entirely refusing to grow in some cases. Deficiency in starch 

 and chlorophyll are noted for this pine on the lime soils, and also to a 

 very slight extent for the Austrian pine on soils with extremely high 

 calcium-carbonate content. The chloroplasts of the chlorotic plants are 

 said to be small. The poor condition is attributed to potash hunger, 

 and no mention is made of iron hunger as a possible cause. Ash analyses 

 showed the following conditions : 

 On good soil, 



Pinus pinaster, potash 16 per cent, iron oxid 3.8 per cent, linie 

 40 per cent. 



On excessively calcareous soil, 



Pinus pinaster, potash 5 per cent, iron oxid 2.1 per cent, lime 



56 per cent. 



Pinus austriaca, potash 14 per cent, iron oxid 3.3 per cent, 

 lime 49 per cent. 



Sachs (20) reports chlorosis in young trees of Abies balsamea, A. 

 apollonis, and A. bicolor and says that entirely chlorotic new growth 

 becomes green more or less promptly after considerable quantities of 

 solid iron sulphate are placed in ditches in the soil near the roots. No 

 controls are mentioned, but the promptness with which the younger 

 trees are reported to have responded to the treatment supports his con- 

 clusion that the recovery was due to the iron added, despite the fact 

 that fast-growing chlorotic shoots, according to his own statement, 



