14 
BULLETIN 837, IT. S. DEPARTMENT OF AGRICULTURE. 
In Table IV are brought together all of the data bearing on the 
time and number of spray applications, arranged by vineyards and 
varieties. This table provides for a comparison of the plats within 
each vineyard by reading from top to bottom, as well as a com- 
parison of the plats receiving similar spray treatment in the different 
vineyards, by reading across. While the comparison between plats 
within a vineyard is relatively consistent, considerable variations 
exist between vineyards. A study of the column of averages shows 
satisfactory commercial control to have been effected in all plats 
which received either two or three spray applications with the excep- 
tions of the first two plats. These two plats illustrate the necessity of 
timeliness of spraying and adhesiveness of spray material, since in 
1917 the more timely spray treatment, and the use of resin fish-oil 
soap throughout, reduced the average infestation from 19 per cent 
in 1916 to 5 per cent in 1917. 
RELATIVE EFFICIENCY OF DIFFERENT TIMES AND NUMBERS OF SPRAY 
APPLICATIONS. 
Table V. — Summarized results -from Table IV — relative efficiency of different 
times amd numbers of spray applications, 1916, 1917, and 1918 — Arsenicals 
applied in Bordeaux mixture and soap solution* 
a 
o 
o 
ffi 
"3 
.2 
o 
OB 
L 
ft<S 
ffi ffi 
la 
Percentage of grape berries infested, aver- 
CD 
,a 
<» <3 
ft+j 
03 w 
t- 3 
k 
gtf 
ffi o 
m 
■d 
ages of all experiments, 1916, 1917, 1918. 
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ft 
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03 
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B.S 
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fl'Sb 
ffi ffi 
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ffi 
a 
CO 
~03 
o 
8 
03 
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IS 
n 
-d 
> 
o 
o 
03 
ft 
■s 
ft 
■s 
1 
ft 
a 
GO 
g 
©& 
03 o 
g~ 
tn 
(4 
ffi 
a 
ffi- 
a 
T3 
ffi 
>, 
03 
S 
>> 
1 
03 
a 
o 
03 
3 
.3, 
S 
& 
£ 
i® 
3 
3 
ft 
"3 
ft 
"O 
ft 
-3 
£ 
Ph 
gq 
EH 
««{ 
^ 
fc 
ft 
CQ 
< 
Ul 
■^ 
Ul 
<j 
2 
X 
X 
2£ 
1916,1917 
9 
11 
11.35 
79.22 
3.04 
48.20 
2.11 
39.67 
2 
X 
X 
2| 
1916 
3 
4 
18.99 
83.98 
2.31 
22.67 
2 
X 
X 
11 
2| 
2£ 
1917,1918 
11 
14 
4.67 
64.92 
.82 
26.00 
1.53 
16.85 
2 . 
X 
x" 
X 
X 
X 
X 
1917, 1918 
1916 
1916 
5 
3 
6 
6 
4 
8 
1.11 
2.66 
1.32 
35.64 
22.67 
66.26 
2.07 
30.14 
2 
5.78 
6.86 
79.27 
79.98 
3 
X 
3 
X 
X 
X 
l 
1917, 1918 
5 
5 
.41 
42.00 
1.21 
52.96 
1.31 
17.92 
1 
X 
1916. 1917 
1917. 1918 
1918 
6 
4 
2 
7 
4 
2 
16.90 
79.77 
6.21 
13.30 
31.91 
26.40 
7.23 
8.75 
2.08 
39.67 
1 
X 
X 
9.89 
2 
X 
7.39 
62.36 
6.93 
1 
X 
H 
1918 
2 
2 
25.67 
82.82 
4.20 
10.04 
A comparison of the combinations of the first and second sprays 
with first and third sprays shows little choice between them as far 
as berry-moth control is concerned. Since the combination of the 
first and second sprays leaves the fruit practically free of all spray 
residue at harvest time and since the second spray is more easily ap- 
plied than the third because of lighter grape foliage, this combina- 
tion of the first and second application is preferred by the writers. 
It is important to know, however, that if for any reason the second 
spray can not be made, the third may be applied and will give about 
