Maya, 1921 Effect of Ferrous Sulphate on Chlorosis of Conifers 159 



cessive amount, except possibly in plot D. This experiment was carried 

 on in a section of the nursery in which the disease did not prove to be 

 prevalent, and little chlorosis occurred in any of the plots. The entire 

 number of yellow seedlings shows an increase with increased watering 

 through all four plots for the last three counts and a somewhat less 

 marked but similar relation for the earlier counts. The magnitude of 

 the difference is, however, not sufficient to permit positive conclusions. 

 Whether the apparent effect of the watering in increasing chlorosis was 

 mostly due to the solutes in the excess water, to cooling the soil, or to 

 hindering aeration, it is not possible to say. That the entire effect of 

 the watering should have been due to disturbance of aeration, or tem- 

 perature, seems scarcely possible in the cases of plots B and C, which 

 received relatively little artificial watering. These plots did not seem 

 excessively wet, but the soil of plot D was sufficiently wet to permit the 

 development of moss abnormally wet for this nursery. 



II. Effects of different amounts of artificial "watering on chlorosis in 4- to 5- 

 month-old Douglas fir seedlings 



a Two square feet counted in each plot. Number of seedlings per square foot at beginning of test: Plot A, 

 241; B, 244; C, 363; D, 278. 

 & Figures in parenthesis indicate total number of days on which rain or artificial watering occurred. 



A pathologic condition may be encountered in certain conifers growing 

 in wet situations. This condition would be unfavorable and therefore 

 would result in subnormal vigor and growth of the plants subjected to 

 such abnormal conditions. In studying hypertrophied lenticels at the 

 Bessey Nursery, near Halsey, Nebr., one of the writers (8) conducted an 

 experiment in heavy watering, in which irrigations approximately equiva- 

 lent to 2.2 inches of rainfall were repeated 17 times during a period of 

 three months on western yellow pine transplants grown two years in the 

 seed bed and one year in the transplant bed. Considerable chlorosis 

 appeared in the heavily watered beds, the plants of which were originally 

 thrifty and free of chlorosis, while the controls remained nonchlorotic. 

 There is also a possibility of a lack of proper aeration of the soil and of 



