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 Aj sprayed with 

 Pickering spray held S00 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. ^ 



All 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. 



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 loaves or fruit. 



