CONTROL OF THE GRAPE-BERRY MOTH. 
27 
Results in this vineyard showed that spraying will control the 
grape-berry moth fully as well in the very compact clusters of the 
Niagara grapes as in the less compact Concord. The test was thor- 
ough, as shown by the heavy infestation in the checks. Arsenate 
of lead used at the rate of 5 pounds (paste) to 50 gallons of liquid 
(Plat I) did not appear to have any advantage over 3 pounds to 50 
gallons (Plat II). 
The Spray Mixture. 
ARSENATE OF LEAD, AMOUNT NECESSARY. 
Arsenate of lead, either as paste or as powder, was the insecticide 
used in all field experiments. In all instances but one, when used 
at the rate of 3 pounds, paste, or 1^ pounds, powder, to 50 gallons 
of liquid, the amount was sufficient to reduce the grape-berry moth 
satisfactorily. During the seasons of 1915 and 1916 at least one plat 
was sprayed with poison at the above rate, and one other plat was 
sprayed under conditions as nearly the same as possible except that 
the amount of poison was increased to 5 pounds of paste or 2 \ pounds 
of powder to 50 gallons of liquid. In all instances except the one 
referred to no distinct advantage was shown in favor of the higher- 
amount, while in two of the vineyards the plats sprayed with the 
higher amount were actually the more heavily infested. The differ- 
ences in results that did appear were usually slight and could be 
accounted for largely by variation of infestation. The comparative 
value of the two amounts of poison as it appeared in the different 
vineyards is summarized in Table 20. 
Table 20. — Relative efficiency of arsenate of lead at the rate of 3 pounds and 5 pounds 
(paste) to 50 gallons of liquid. 
Treatments 
common to all 
plats. 
Years 
tried. 
Num- 
ber of 
vine- 
yards. 
Num- 
ber of 
plats. 
Infested grape berries. 
Amount of arse- 
nate of lead. 
Best 
plat. 
Adja- 
cent 
check. 
Poor- 
est 
plat. 
Adja- 
cent 
check. 
Aver- 
age 
of all 
plats. 
Aver- 
age of 
all ad- 
jacent 
checks 
3 pounds paste 
or 1J pounds 
powder to 50 
gallons of water. 
Laundry soap, 
1 pound, 
B o r deaux 
mixture (3-3 
formula). 
50 gallons ap- 
plied twice 
with "trail- 
ers." 
1915, 1916 
1915, 1916 
1915, 1916 
7 
6 
6 
7 
6 
16 
Perct. 
0.89 
Perct. 
50.43 
Per ct. 
8.43 
Per ct. 
75.16 
Per ct. 
4.12 
3.41 
3.34 
Per ct. 
50.03 
49.17 
above. Poor- 
est plat elimi- 
nated. 
5 pounds paste or 
2% pounds pow- 
der to 50 gal- 
lons of water. 
3.15 
75.16 
5.06 
94.83 
54.90 
i Plat II, Miller and Carlburg vineyard, is not included in this average because the results were prejudiced 
by rain. 
Table 20 indicates that as a rule there is practically no difference 
in effectiveness between the two amounts of poison. However, in 
