28 BULLETIN 866, U. S. DEPARTMENT OE AGRICULTURE. 
The results (Table 9) naturally varied with the condition of the 
individual samples. The grapes from plat A, sprayed with standard 
Bordeaux mixture, showed the highest acidity and the lowest sugar 
content, while those from plat 1, treated with Pickering spray con- 
taining 0.64 per cent of copper sulphate, gave the highest content 
of sugar and a low acidity. Since the percentage of sugar increases 
and the percentage of acidity decreases during the ripening of grapes, 
no influence of the sprays in preventing a proper maturing of the 
fruit is indicated. On the contrary, an increase in the sugar con- 
tent and a decrease of acid is evident in the Pickering-sprayed grapes, 
compared with those sprayed with Bordeaux. As no unsprayed 
grapes were analyzed, it is impossible to state whether or not the 
copper in the sprays exerted a stimulating action on the grapes. 
The variation in the composition of the grapes sprayed with Pick- 
ering and Bordeaux may possibly be due to the greater availability 
of the copper in the Pickering sprays. The fact that more burning 
resulted from using the Pickering sprays than from using the 
Bordeaux sprays is evidence of a greater availability, or at least 
solubility, of the copper of the Pickering sprays. It has been sug- 
gested that the effect of the sprays on the composition of the fruit 
came through foliage injury. 
Summary. 
Pickering (A) and (C) sprays, containing 0.64, 0.36, and 0.38 per 
cent of copper sulphate, caused severe injury to the grape foliage 
and fruit after a hail storm which tore the leaves and injured the 
vines both at Vineland, N. J., and Vienna, Va., in 1916. Under simi- 
lar conditions the Pickering sprays containing 0.23, 0.13, 0.115, and 
0.065 per cent of copper sulphate caused less injury than the stronger 
Pickering sprays, but more injury than standard Bordeaux, 3-3-50, 
containing 0.75 per cent of copper sulphate. 
The strongest Pickering spray, that employed on plat 1, controlled 
the black rot fully as well as the Bordeaux, 3-3-50, and the Picker- 
ing sprays containing 0.36 and 0.38 per cent of copper sulphate 
showed practically as effective control as the Bordeaux. The weaker 
Pickering sprays, containing 0.23 per cent of copper sulphate or less, 
did not control the black rot as well as the Bordeaux spray. 
The yield of grapes was reduced by all of the Pickering sprays 
except the two weaker ones. 
The copper of the Pickering sprays did not adhere to the grape 
leaves as well as the copper of the Bordeaux, 3-3-50. The averages 
of all the results obtained, including some not reported in the tables, 
show that where the Pickering sprays were applied with a power 
