PICKERING SPRAYS. 
27 
IN VIRGINIA. 
On June 10 a heavy hail storm broke the leaves, punctured the 
grapes, and broke off many shoots from the vines. Two or three days 
after the storm serious burning of the leaves was noticed. This in- 
jury was particularly severe on the plats sprayed with the strongest 
Pickering solutions. The weakest Pickering spray produced about 
the same injury as the Bordeaux spray. On June 26 new growth 
appeared on all the sprayed vines, and a fourth spraying was made 
on July 3, with no additional spray injury. As in the case of the 
tests in New Jersey, the injury to the leaves was in direct proportion 
to the percentage of copper sulphate present in the Pickering sprays. 
Among the numerous theories advanced to explain the burning 
or scorching of foliage by copper sprays are the following: (1) A 
specific susceptibility of the protoplasm of the plant to copper; 
(2) solvent properties or activities of the cell sap of the plant on the 
copper compound of the spray; (3) permeability of the epidermis or 
cuticle to the cell contents when conditions are favorable for exos- 
mosis and for a trace of copper which has been rendered soluble; 
(4) weather conditions following spraying, particularly moisture, 
which provides suitable conditions for the exosmosis of some of the 
contents of the cells of leaves; (5) the amount of spray on the leaves 
or foliage, the proportions of other constituents, such as lime, to the 
copper in the spray, the condition of the leaves, whether normal or 
injured by the weather, insects, etc., and, above all, the climate. 
Effect on Maturing of Fruit. 
IN VIRGINIA. 
At the time of picking, samples of grapes from the different plats 
were analyzed for reducing sugar, sucrose, and acidity, using the 
methods of the Association of Official Agricultural Chemists, in 
order to determine the influence of the sprays in preventing a proper 
maturing of the fruit. 
Table 
9. — Effect of various sprays on 
composition of 
grapes ( " 
Virginia) 
Plat. No. 
Spray used. 
Copper 
sulphate 
in spray 
used. 
Composition of grapes at 
picking time. 
Reducing 
sugar. 
Sucrose. 
Acidity. 
A 
Bordeaux, 3-3-50 
Per cent. 
0.75 
.64 
.38 
.38 
.13 
.23 
.36 
Per cent. 
7.35 
10.52 
8.57 
8.54 
7.50 
9.10 
7.60 
Per cent. 
0.07 
.22 
.42 
.10 
.10 
.28 
.20 
Cc. nor- 
mal al- 
kali per 
kilo. 
162 
1 
152 
2 
do 
159 
2b 
Pickering (A) and rosin-fish-oil soap. 
157 
3 
155 
5 . . 
Pickering (C) 
152 
7 
do 
151 
