32 
BULLETIN 866, U. S. DEPARTMENT OF AGRICULTURE. 
At the time of the third spraying it was noticed that three or four 
apples on the check tree were infected with bitter rot, whereas the 
sprayed trees seemed to be entirely free from it. On August 13, 
the date of the fourth application, one or two apples on the Pickering- 
sprayed, barium-water-sprayed, and Bordeaux-sprayed trees were 
infected with bitter rot, while the check tree showed a fairly large 
amount of rot. 
At the time of picking very little bitter rot was found on any of 
the trees. The Bordeaux spray gave 100 per cent protection from 
bitter rot. The barium-water spray gave a better control of bitter 
rot than the Pickering spray. The 1918 results (Table 10) are incon- 
clusive because of the small number of apples infected with bitter 
rot on the sprayed trees. 
Adherence of Copper from Various Sprays to Leaves. 
IN 1916. 
One set of leaves was gathered from the sprayed and check trees 
on July 12, 13 days after the second spraying, and a second set on 
July 13, three hours after the third spray had been applied. The 
outlines of these leaves were immediately traced on paper, and later 
measured with a polar planimeter. The area of each set of 50 leaves 
was calculated, but one side of the leaves being used in the calcula- 
tion. Later the leaves were dried, and the copper determined in each 
set (Table 11). 
Table 11. — Adherence of copper from various sprays to apple leaves (Virginia). 
Spray used. 
Copper 
sulphate 
in spray 
used. 
Time 
between 
spraying 
and 
gathering 
of leaves. 
Copper adhering to leaves. 
Plat No. 
Parts per 
million 
(dry 
basis). 
Parts per 
million 
per 0.1 
per cent 
of CuS0 4 
in spray. 
Mg. per 
square 
meter of 
leaf 
surface. 
Mg. per 
square 
meter of 
leaf 
surface 
per 0.1 
per cent 
CuS0 4 
in spray. 
1916. 
Bordeaux, 4-5-50 
Per cent. 
1.00 
.13 
.065 
.23 
.115 
1.00 
.13 
.065 
.23 
.115 
Days. 
13 
13 
13 
13 
13 
i 
i 
i 
I 
i 
i 
15 
15 
15 
15 
15 
15 
15 
425 
59 
90 
248 
77 
3,150 
260 
185 
646 
249 
42.5 
45.4 
138.5 
107.8 
67.0 
315.0 
200.0 
284.6 
280.9 
216.6 
26.0 
1.3 
9.3 
25.6 
2.2 
266.6 
16.0 
10.2 
15.9 
20.3 
2.6 
3 
1.0 
4 
do 
14.3 
5 
11.1 
6 
do 
1.9 
Bordeaux, 4-5-50 
26.7 
3 
12.3 
4 
do 
15.7 
5 
Pickering (C) 
6.9 
6 
do 
17.7 
Check 
1917. 
Bordeaux, 4-4-50 
1.00 
644 
6.6 
316 
255 
206 
146 
62 
64.4 
33.8 
.3 
15.5 
12.5 
10.5 
6.5 
3.0 
3.4 
Check 
Bordeaux, 2-1-50 
Bordeaux, 2-2-50 
Pickering (A) 
.5 
.5 
.50 
.25 
.125 
63.2 
51.0 
41.2 
58.4 
49.6 
3.1 
2.5 
Ai 
2.1 
A 2 
do 
2.6 
A3 
do 
2.4 
