May 2 ,1921 Effect of Ferrous Sulphate on ChloYosis of ConifeYS 
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. 
Table II .—Effects of different amounts of artificial watering on chlorosis in 4 - to 5- 
month-old Douglas fir seedlings 
Plot A, 
un¬ 
watered. b 
Plot B, 
lightly 
watered. & 
Plot C, 
moderately 
watered. b 
Plot D 
heavily 
watered. & 
1917 - 
Rainfall and artificial watering (in inches): 
First half of August. 
Traces. 
o- 54 (3) 
• 34 (4) 
I. 
1.11 (3) 
• AX (a) 
1-65 (3) 
• Cl (a} 
Last half of August. 
o- 25 (3) 
1.07 (6) 
• 71 (2) 
First half of September. 
• \*t/ 
I. 61 (7) 
• JJ 
I. OI ( 7) 
Last half of September. 
1.07 (6) 
. 18 (2) 
I. AX ( 6 ) 
A *y* \ // 
1.83(6) 
• 56 (2) 
First half of October. 
•36 (2) 
Total, Aug. 2 to Oct. 6. 
2.03 (11) 
3-47 (22) 
4.94 (22) 
6.48 (22) 
Percentage of seedlings found chlorotic:« 
Sent. 1. 
7.8 
11. 8 
7. c 
TO. 7 
Sept. 13. 
6.1 
7. O 
1 7 * y 
T 4 . 7 
Sept. 22... 
T* 7 « 
C. T 
14. 7 
8 A 
Oct. 2. 
. A 
4 * j 
2* 2 
a 
O. 4 
4-8 
A . O 
Oct. 22. 
• *r 
• A 
2* 2 
+* y 
2* 6 
* *f 
4. U 
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. 
b 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 (<?) 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 
