Maya, 1921 Effect of Ferrous Sulphate on Chlorosis of Conifers 155 



usually improve in color toward the end of the season without any special 

 treatment. 



An interesting American report is that on chlorosis of Sequoia 

 sempervirens by Peirce (17). 



CHLOROSIS OF CONIFER NURSERY STOCK IN THE UNITED STATES 



At several of the nurseries of the United States Forest Service in 

 Nebraska and farther west, conifers are occasionally somewhat chlorotic 

 The condition has become a matter of importance, however, only in the 

 Morton Nursery, in northwestern Nebraska, and the Pocatello Nursery, 

 in southern Idaho. Chlorosis has also been noted in conifers at the 

 Great Basin Experiment Station in central Utah, especially in lodgepole 

 pine (Pinus contorta) seedlings and transplants grown two years in 

 the seed bed and one year in the transplant bed. At the latter locality 

 native aspen (Populus tremuloides) was also chlorotic in places. 



ANALYSES OF SOIL AND WATER 



At all the points at which chlorosis was found, analysis (by courtesy 

 of the United States Bureau of Soils for the nursery soils, and of Dr. 

 J. E. Greaves, of the Utah Agricultural Experiment Station, for the 

 Great Basin Experiment Station soils, showed the presence of carbonates 

 as indicated by carbon-dioxid evolution. Carbon dioxid was, however, 

 reported from sites near the Great Basin Experiment Station on which no 

 chlorosis had been observed in either aspen or conifers, and from a 

 nursery at which chlorosis had never been serious. In some cases the 

 amount reported from soils on which the trees were green was greater 

 than from those where the trees were chlorotic. The acid-digestion 

 analyses showed for all the soils on which chlorosis was observed a con- 

 siderable amount of calcium, much greater than that ordinarily found in 

 the humid region of the United States, and in every case greater than the 

 average of the 570 soils of the arid region reported by Hilgard (10, p. 377) . 

 However, there is little apparent correlation between the amount of chlo- 

 rosis and the amount of calcium reported. The Utah soil on which coni- 

 fers were not chlorotic yielded over 17 per cent of lime (as CaO) and 12% 

 per cent of carbon dioxid. The Pocatello nursery soil on which chlorosis 

 was serious yielded more than twice as much calcium (2.9 to 4.7 per 

 cent CaO) as Hilgard 's average for arid soils. It was not an excessively 

 calcareous soil, however, as compared with some of the soils reported in 

 connection with chlorosis in Europe and Porto Rico, with the chalk soils 

 reported by Somerville (22) on which healthy Douglas fir was growing, 

 or with the Utah soil just mentioned as supporting normally green coni- 

 fers. The phosphorus (as P 2 O 5 ) for the Pocatello soil was reported as 

 approximately 0.7 per cent for all the samples, an unusually high figure. 

 This at once suggests a possible relationship, in view of the slight 



