28 
BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 
the Southwick vineyard, 1916 (Plats I and II), the results in the 
plat sprayed with the higher amount appeared so much better in the 
final counts that the result could hardly be accounted for by variable 
infestation. Moreover, checks on either side showed that very little 
variation existed. In this vineyard at one end, although not through- 
out the vineyard, the checks showed an infestation very near to 
total, and probably enough moths had emerged to have totally 
infested a crop several times as heavy. Under such conditions of 
extremely heavy infestation the higher amount of poison was more 
effective. As previously stated in the discussion of results in the 
Southwick vineyard, the two amounts of poison were apparently 
equally effective when the first counts were made, but the higher 
amount withstood the weathering better and was more eff ectivea gainst 
the late second brood. 
ADHESIVE S. 
The necessity of adding adhesives to the spray mixture became 
apparent to the writer in the experiments in 1914. It was readily 
observed that the spray solutions from which an adhesive was absent 
did not adhere to the waxy skin of the grape berries, and this was 
undoubtedly one of the chief reasons for the failure to control the 
grape-berry moth during that season. The solutions to which soap 
was added appeared to adhere much better, but since this was used 
only in the last application a definite contrast in the final count was 
not shown. The counts in plats where soap had been added to the 
spray solution and applied with " trailers, " however, when compared 
with counts in the nearest checks are consistently better than the 
others. 
The effect of applying a spray mixture without adhesives was 
specifically demonstrated in 1915 by a comparison of the results in 
Plats V and IX in the Miller and Carlburg vineyard, pages 18-19. 
Table 21. — Relative effectiveness of spray mixtures with various adhesives and without 
adhesive. 
(Treatments common to all plats: Arsenate of lead, 3 pounds of paste or 1| pounds of powder; Bordeaux 
mixture (3-3-50 formula) applied twice with "trailers.") 
Years 
tried. 
Num- 
ber of 
vine- 
yards. 
Num- 
ber of 
plats. 
Infested grape berries. 
Kind of adhesive used. 
Best 
plat. 
Adja- 
cent 
check. 
Poor- 
est 
plat. 
Adja- 
cent 
check. 
Aver- 
age 
of all 
plats. 
Aver- 
age of 
all ad- 
jacent 
checks. 
1916 
1 
2 
3 
4 
7 
1 
1 
1 
1 
2 
3 
4 
7 
1 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
Per ct. 
2.14 
1.97 
3.95 
4.14 
4.12 
19.60 
18.89 
21.05 
Perct. 
55.93 
Fish-oil soap (without i 1916 only, 
resin). 
Do 1 1915,1916 
Laundry soap 1916 onlv. 
31.29 
0.47 
25.76 
7.91 
65.94 
42.84 
61.79 
Do 
1915, 1916 
.89 
50.43 
8.43 
75.16 
50.03 
1916 
1915 
1915 
33.99 
1 
1 
28.80 
28.80 
