24 
BULLETIN 550, U. S. DEPARTMENT OF AGRICULTURE. 
Table 15. — Percentage of infestation in experimental plats, Southwick vineyard, North 
East Pa., 1916. 
Number 
of 
vines. 
Number 
of 
clusters. 
Total 
berries. 
First brood. 
Second brood. 
Plat No. 
Infested 
berries. 
Infesta- 
tion. 
Infested 
berries. 
Infesta- 
tion. 
Check A. 
20 
20 
20 
20 
20 
20 
609 
570 
638 
623 
585 
584 
16,443 
15, 960 
19, 778 
15,575 
14,625 
16,936 
15, 200 
2,866 
565 
597 
2,129 
1,364 
995 
1,073 
Per cent. 
17.43 
3.41 
3.02 
13.61 
9.32 
5.87 
7.06 
11,635 
1,339 
835 
11, 706 
4,966 
3,242 
9,963 
Per cent. 
70.76 
I 
8.43 
II 
4.22 
Check B 
75 16 
Ill 
33.95 
IV 
19.13 
Check C 
608 
65.65 
A/0/P7?? 
tnrsr 
s 
227 
cs* ec* 
227 
JZ7 
f/4ST 
The final counts in this vineyard showed that the grape-berry moth 
had been controlled in the plat where two applications with " trailers " 
had been made, using arsenate of lead (powder) at the rate of 2 J 
pounds to 50 gallons with an 
adhesive (Plat II). This was 
in the face of a very heavy in- 
festation in the checks. In 
contrast to the results in all 
other vineyards, in the plat 
in which 1 J pounds of arsen- 
ate of lead (powder) was used 
the final count was distinctly 
less satisfactory (Plat I). 
This difference was conspic- 
uous only at the north end of 
the vineyard, where the in- 
festation in the checks was practically total and where several eggs 
had been deposited on a majority of the berries. It should be noted 
that the contrast was not apparent until the second-brood counts 
were made, and the first-brood infestation was about the same in 
both plats. An unusually large percentage of second-brood larvae 
found in Plat I were very late, indicating that the early second 
brood had failed to enter the berries. This would indicate that the 
two amounts of poison were equally effective for some time, but that 
the higher amount withstood the weathering better. 
Two applications (1) with "set nozzles" and (2) with " trailers" 
(Plat IV) were partially effective, though not satisfactory. A single 
application with " trailers" when the berries were just touching 
(Plat III) was entirely unsatisfactory. 
sours/ 
Fig. 8.— Diagram showing arrangement of experimental 
plats in the vineyard of Mr. J. M. Moorhead, Moorhead- 
ville, Pa., 1916. (Original.) 
