34 BULLETIN 550, U. S. DEPABTMENT OE AGEICULTUEE, 
Table 23. — Relative efficiency of different times and numbers of applications. 
Treatments 
common to 
all pjats. 
Years 
tried. 
Num- 
ber of 
vine- 
yards. 
Num- 
ber of 
plats. 
Inie 
sted grape berries. 
Time and number 
of applications. 
Best 
plat. 
Adja- Poor- j Adja- 
cent est cent 
check. 1 plat, check. 
Aver- 
age 
of all 
plats. 
Aver- 
age of 
all ad- 
jacent 
:iif:kf. 
Two applications 
after blossoms 
hare fallen and 
when grape ber- 
ries are touch- 
tag. 
Two applications, 
same as above, 
including only 
plat adjacent 
to that sprayed 
3 times. 
Three applica- 
tions, 2 same as 
above; third 5 
weeks after first. 
One application 
when grape ber- 
ries are touch- 
ing. 
One application 5 
weeks after fall- 
ing of blossoms. 
Arsenate of lead, 
3 pounds paste 
of 1| pounds 
powder; laun- 
dry soap, 1 
pound; Bor- 
deaux mix- 
ture (3-3-50), 
applied with 
"trailers." 
do 
1915, 
1916 
1916 
1916 
:;:: 
1916 
7 
1 
1 
1 
: 
1 
1 
3 
1 
P.ct. 
0.S9 
1.57 
.68 
5.25 
19.97 
P.ct. 
50.43 
79.72 
67.52 
23.39 
55.53 
P.ct. 
8.43 
1.57 
.68 
33.95 
19.97 
P.ct. 
75.16 
79.72 
67.52 
75.16 
55.53 
P.ct. 
4.12 
1.57 
.68 
18.71 
19.97 
P.ct. 
50.03 
79.72 
do 
do 
67.52 
51.29 
(i) 
55.53 
1 Same as above, except arsenate of lead, 2 \ pounds, and resin fish-oil soap instead of laundry soap. 
FACTORS DETEBMININGr THE TIME AND NUMBER OE APPLICATIONS. 
The time and number of applications are determined not only by the 
seasonal history and habits of the grape-berry moth, but also by the 
development of the grape itself. Fortunately the times for spraying, 
most favorable in relation to the pest and also in relation to the crop, 
are nearly coincident. It is probable, therefore, that the vineyardist 
will find it most convenient to time his operations entirely by the 
development of the fruit. 
The first spraying probably destroys the largest number of first- 
brood larvae, for it is applied just before they begin hatching in num- 
bers. Besides these, it also destroys some larvae which hatch before 
the blossoms fall and are feeding in the cluster, but have not entered 
a grape berry. Following this application the grapes grow very rap- 
idly and the larger part of the berry surface does not long remain 
covered. But as at this time the majority of the larva? enter the 
berry at the stem end, where the spray always collects, compara- 
tively few escape. 
The second application is made after first-brood hatching begins to 
decline, but it is effective against the second brood also. As soon as 
the berries begin to touch, the majority of larvae begin entering at 
the points of contact instead of at the stem ends. Spray which is 
