30 
BULLETIN 169, U. S. DEPARTMENT OF AGRICULTURE. 
before sowing and did no perceptible damage to pines or pine seed. 
This was true even in series 508, plat G, in which 0.75 fluid ounce per 
square foot was applied six days before sowing and evaporation 
allowed for only three days before sowing. The effect of formalin, on 
the weed stand seemed approximately equivalent to that obtained 
with one-half or one-third the volume of sulphuric acid. As the 
weight of H 2 S0 4 per fluid ounce of acid used was at least four times 
as great as the weight of HCHO in the formalin, the formaldehyde 
appears rather more effective, weight for weight, in keeping down 
weeds. The radical difference in the type of action of the formalin 
against the pines renders impossible any direct comparison with acid. 
LIME-SULPHUR SOLUTION. 
The results in series 519, plats R and S (Table VI), are contra- 
dictory. Injury to pines from fairly heavy applications of lime-sulphur 
at the time of sowing can probably be prevented by sufficient water- 
ing during the germination period. The injury to weeds occurred 
despite heavy watering. 
EXPERIMENTS AT MORRISVILLE, PA. 
During the season of 1912, in pursuance of recommendations by 
the writer, tests with sulphuric acid were conducted by Mr. II . E. 
Lee, under the direction of Mr. John Foley, forester of the Pennsyl- 
vania Railroad, at the nursery near Morrisville, Pa. Sulphuric acid 
only was used. All treatments tested resulted in a decreased stand. 
The results of very weak treatments on beds given ordinary nursery 
watering are shown in Table VII. 
Table VII. — Evidence of injury to pines by sulphuric acid applied at the time of sowing, 
Morrisville, Pa. 
Plat. 
Num- 
ber of 
plats 
aver- 
aged. 
Species. 
Sowing 
to germi- 
nation. 
Acid per 
square 
foot. 
Watering. 
Final 
stand, 
taking 
average 
of checks 
as 100. 
Decrease 
in stand 
appar- 
ently 
due to 
acid. 
Series 631.. 
( \ 
16 
21 
7 
17 
7 
14 
1 
1 
1 
1 
1 
1 
Pinus ponderosa 
do 
do 
Days. 
6to 9 
6 to 9 
6 to 9 
9 to 10 
16 to 21 
7 
9 to 12 
11 
8 to 10 
Fluid oz. 
0.031 
.042 
.083 
.083 
.083 
.083 
.083 
.083 
.083 
.188 
.25 
.375 
.188 
.25 
.375 
Only as in ordi- 
nary nursery 
practice. 
0.15 inch, twice 
daily. 
f 91 
95 
90 
55 
27 
74 
63 
56 
62 
34 
26 
I 4 
f 83 
53 
45 
Per cent. 
9 
5 
10 
Series 632.. 
Series 633.. 
Series 634.. 
Series 635 . . 
Pinus resinosa 
Pinus strobus 
Pinus sylvestris 
do 
45 
73 
26 
37 
Series 636.. 
Series 637.. 
Series 638: 
A 
D 
c 
G 
F 
J 
Piceaexcelsa 
Pinus sylvestris 
do 
do 
do 
do 
do 
do 
44 
38 
66 
74 
96 
17 
47 
55 
