34 BULLETIN" 866, U. S. DEPARTMENT OF AGRICULTURE. 
Of the leaves picked two weeks after spraying, those receiving the 
Bordeaux, 4-4-50, held the most copper. The leaves sprayed with 
Bordeaux, 2-1-50, held more copper than those on which 2-2-50 
spray was used. No important differences were noted between the 
adhesive properties of the copper of the Pickering (A) and (C) sprays. 
In three cases the leaves treated with the Pickering sprays held prac- 
tically the same amount of copper per 0.1 per cent of copper sul- 
phate used as the leaves sprayed with Bordeaux, 4-4-50. The other 
three Pickering sprays gave lower results. The results for copper on 
the leaves by area were slightly in favor of the Bordeaux spray. 
The analyses of the second set of leaves, gathered nearly four 
weeks after spraying, showed the most copper on the Bordeaux- 
sprayed leaves, although the leaves from plat A t sprayed with 
Pickering spray held 800 parts of copper per million. Contrary to 
the results recorded on page 19, the leaves receiving the Bordeaux, 
2-1-50, spray did not hold as much copper as those sprayed with 
the Bordeaux, 2-2-50. 
Ail of the Pickering-sprayed leaves held more copper than the 
Bordeaux-sprayed leaves per unit of copper sulphate in the spray 
applied, indicating that per unit of copper sulphate present in the 
spray the copper of the Pickering sprays adheres to apple leaves in 
larger proportions .than the copper of standard Bordeaux spray. 
IN 1918. 
Leaves from the trees sprayed with Pickering, barium water, and 
Bordeaux and from the check tree were collected on June 28, just 
after spraying, and July 26, 1918, 28 days after spraying, and analyzed 
for copper. The results appear in Table 11. 
As the period from the time of the collection of the first set of 
leaves until the collection of the second set was very dry, about as 
much copper was found on the second set as on the first set of leaves. 
The results for the leaves picked immediately after spraying, per 
0.1 per cent of copper sulphate present in the sprays, are highest for 
those- receiving the barium-water spray. The Bordeaux-sprayed 
and the Pickering-sprayed leaves gave practically the same results. 
The results for the leaves picked 28 days after spraying from Picker- 
ing-sprayed trees are low, while those for the barium-water- and the 
Bordeaux-sprayed leaves are practically identical. 
Injury to Leaves and Fruit. 
IN 1916. 
Although the season was wet and sultry, only a trace of injury to 
the leaves and fruit was noted on the trees. treated with Pickering 
spray. This injury had no practical significance. The Bordeaux 
spray did not injure the leaves or fruit. 
