PICKERING SPRAYS. 
19 
sprayed with Pickering (A) and (C) sprays varied markedly. On an 
average more copper was found on the leaves sprayed with Pickering 
(C) sprays than on those treated with Pickering (A) sprays. 
Table 5.— Adherence of copper from various sprays to potato leaves (northern Maine). 
Spray. 
Cop- 
per 
sul- 
phate 
in 
spray. 
Copper adhering to leaA 
es. 
Plat 
No. 
Parts per million 
(dry basis). 
Parts per mil- 
lion per 0.1 
per cent 
CuS0 4 in 
spray (dry 
basis). 
Mg. per 
square meter 
ofleafsurface. 
Mg. per 
square meter 
ofleafsurface 
per 0.1 per 
cent CuS0 4 
in spray. 
Lot I.* 
Lot 2.2 
Lot*. 1 
Lot 2.2 
Lotl. 1 
Lot 2.2 
Lot I. 1 
Lot 2.2 
1916. 
Standard Bordeaux, 
5-5-50 
Pa- 
cent. 
1.25 
.64 
.38 
.13 
.065 
.23 
.115 
.36 
.38 
.38 
.7 
.6 
.6 
.5 
.5 
.4 
.4 
.3 
,5 
.5 
.5 
1.25 
163.3 
149.7 
29.4 
35.8 
9.11 
42.9 
36.6 
61.8 
120.8 
73.6 
519.8 
455.1 
422.6 
338.1 
277.5 
274.2 
111.9 
138.6 
141.4 
128.9 
213.3 
387.4 
332.6 
53.7 
22.3 
19.6 
7.2 
23.8 
18.9 
97.9 
54.0 
38.0 
571.7 
533.9 
373.6 
431.5 
334.5 
319.3 
200.5 
163.3 
338.0 
275.0 
390.0 
1,073.7 
41.8 
22.05 
956. 19 
1,641.60 
1,098.0 
16.9 
878.3 
1,217.5 
1,703.0 
1,700 
1,100 
1,700 
1,500 
1,200 
2,300 
13.0 
23.4 
7.7 
27.6 
14.0 
18.7 
31.8 
17.2 
31.8 
19.4 
74.2 
75.8 
70.4 
69.6 
55.5 
68.6 
28.0 
46.2 
28.3 
25.8 
42.7 
31.0 
26.6 
8.4 
5.9 
15.1 
11.1 
10.3 
16.4 
27.2 
14.0 
10.0 
81.7 
89.0 
62.3 
86.3 
66.9 
79.8 
50.1 
54.4 
67.6 
55.0 
78.0 
86.0 
31.15 
15.77 
8.00 
11.64 
.80 
7.97 
5.99 
12.80 
24.13 
5.98 
11.17 
10.64 
10.96 
6.98 
5.34 
6.25 
2.11 
3.32 
2.96 
2.66 
4.38 
7.55 
18.61 
13.07 
10.39 
14.13 
8.96 
9.10 
7.00 
3.97 
9.24 
8.57 
10.02 
30.00 
2.5 
2.4 
2.1 
9.0 
1.2 
3.5 
5.2 
3.6 
6.4 
1.6 
1.60 
1.77 
1.83 
1.40 
1.07 
1.56 
.53 
1.11 
.59 
.53 
.88 
.60 
Pickering (A) 
'.'.'.'.'.'.'.'. 
do 
do 
do 
Pickering (C) 
do 
do 
Pickering (A) and 
rosin-fish-oil soap 
Barium water 
1917. 
1 
Pickering (A) 
2.66 
2 
. . . .do 
2 18 
3 
Pickering (C) 
1.73 
4 
Pickering (A) 
1.83 
5 
do. 
1.80 
6 
do 
1 82 
7 
Pickering (C) 
1.78 
8 
12 
13 
14 
* Check." 
* Check. 
do 
Pickering (A) and 
rosin-fish-oil soap 
Pickering (A) and 
lead arsenate 
Pickering (C) and 
lead arsenate 
Bordeaux, 5-5-50 
1.32 
1.85 
1.71 
2.00 
2.40 
Check.' 
Bordeaux, 3-3-50 
Bordeaux, 5-5-50 
Bordeaux, 3-1^-50 
.75 
1.25 
.75 
363.0 
566.4 
618.1 
48.4 
45.3 
82.4 
127.5 
131.3 
146.4 
5.87 
22.12 
11.41 
31.71 
48.74 
31.44 
.78 
1.77 
1.52 
4.23 
3.90 
4.19 
Barium water. . 
.7 
1.25 
1.25 
.7 
.7 
1.0 
1.0 
1.0 
1.25 
.6 
.6 
.6 
.6 
.6 
271.4 
38.8 
236 
200 
195 
185 
140 
180 
217 
233 
233 
200 
150 
125.5 
97.4 
136.4 
243 
157 
170 
120 
184 
5.86 
21.37 
36.19 
51.57 
.84 
3.05 
Burgundy mixture 
Bordeaux, 5-5-50 
Pickering (A) 
2.89 
4.13 
1918. 
1,650 
1,400 
1,950 
1,850 
1,400 
2,250 
1,300 
1,400 
1,400 
1,200 
900 
2 
3 
Bordeaux, 4-4-50 
Bordeaux, 4-2-50 
Bordeaux, 5-5-50 
4 
5 
6 .. .. 
A 
c 
Pickering (C) 
D 
E 
j F 
lead arsenate 
i In 1916, picked two days after spraying, and in 1917, eight days after spraying. 
2 In 1916, picked seven days after spraying, and in 1917, two days after spraying. 
IN 1917. . • 
Leaves picked on August 11, eight days after spraying Got 1) and 
on August 24, two days after spraying (lot 2), were analyzed with the 
results shown in Table 5. 
