356 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
The above readings indicate a sugar content well above the require¬ 
ment for grapes of table quality. The color of the grapes varied from 
dark-blue to blue-black. The average reading for the composite 
samples was 18.14 and the average reading for the selected samples was 
18.68, showing only a slight difference in the quality of the grapes taken 
at random in the more infested portions of the vineyards and in those 
selected for their good appearance and condition. 
The demonstrations do not show what would have been the quality 
of the grapes had the nicotine not been applied to the vines. Such a 
contrast is given in the analyses of Hartzell in 1913 between the sprayed 
and non-sprayed grapes in his series of experiments. His comparisons 
apply only to the seasonal conditions under which his experiments were 
carried out. 
An opportunity was offered for a comparison in the Erie County work 
this season. In one vineyard, apart from the demonstrations, a block 
of grapes did not receive the nicotine spray while a block directly across 
the alley was sprayed with the same outfit used in the treatment of one 
of the demonstration plots. All the conditions in the sprayed and un¬ 
sprayed blocks were otherwise identical. At harvest time samples 
from the sprayed and non-sprayed vines gave the following readings of 
the Brix spindle. 
Table II. Brix Readings, Sprayed and Non-sprayed Grapes, Concord Variety 
Janes 
vineyard. 
Brix Reading 
Composite samples 
Selected 
samples 
1st. 
2nd. 
Average 
Sprayed. 
18.67 
16.87 
17.77 
18.44 
Unsprayed. 
13.69 
14.29 
13.99 
15.79 
Difference. 
4.98 
2.58 
3.78 
2.65 
In the average readings of the composite samples of sprayed and non- 
sprayed grapes there is a difference of 3.78, which indicates an increase 
of approximately 27.01% in the sugar content due to the control of the 
leaf-hopper by the nicotine spray. The season was very favorable for 
ripening the grapes but the color of the grapes from the non-sprayed 
vines was reddish purple while those from the sprayed vines varied 
from dark-blue to blue-black. The results of these comparative read¬ 
ings show that the high sugar content on the demonstration plots was 
due to leaf-hopper control and that the sugar content of grape juice,. 
