26 BULLETIN 866, IT. S. DEPARTMENT OF AGRICULTURE. 



(C) sprays. The leaves sprayed with Bordeaux mixture contained 

 more copper and a higher ratio of copper per unit of copper sulphate 

 present in the spray than the average for those treated with the 

 Pickering sprays, showing that the copper of the Pickering sprays 

 did not adhere to the grape leaves as well as that of the standard 

 Bordeaux spray. The addition of rosin-fish-oil soap to the Pickering 

 (A) spray used on plat 2 did not increase the adherence of copper 

 to the leaves. 



IN VIRGINIA. 



Duplicate sets of leaves from the plats treated with the different 

 sprays were gathered on June 1 (six days after the second spraying) 

 and on June 3 (eight days after the second spraying) and analyzed 

 (Table 8). 



The results, both by weight and area, for the leaves gathered June 1 

 show that the copper of the Bordeaux spray adhered practically 

 twice as well as that from the Pickering sprays. The use of rosin- 

 fish-oil soap seemed to be of decided advantage. These results do 

 not agree with those obtained by analyzing leaves in New Jersey 

 where similar sprays were used. The low results for copper on 

 the Pickering-sprayed leaves in Virginia, as compared with those 

 obtained on leaves treated with sprays of the same formula and 

 strength in New Jersey, may be accounted for in part by the fact 

 that in New Jersey the first two applications were made with a 



power sprayer. 



Injury to Vines. 



in new jersey. 



Until the severe hail storm of June 11 no burning or other injury 

 was noticed on the Pickering-sprayed plats. After the storm, how- 

 ever, the leaves were torn, the grapes were punctured, and young shoots 

 broken from the vines. The Pickering-sprayed plats were then re- 

 duced in size, only one or two rows of the vines treated with the weaker 

 Pickering sprays being continued through the rest of the season. 

 The stronger Pickering sprays were dropped entirely. By July 7 

 new foliage had appeared on all the vines and no additional injury 

 was evident. 



Copper sprays used on grapes are often mixed with lead arsenate. 

 Lead arsenate, however, was not used with the Pickering or Bordeaux 

 sprays in this investigation. Consequently its influence on the 

 burning of the foliage was not determined. 



The Pickering sprays containing 0.23 per cent and more of copper 

 sulphate controlled the fungous diseases as well as the Bordeaux 

 spray. As commercial sprays, however, they arc impracticable 

 because of their tendency to injure the grape leaves and fruit. The 

 use of rosin-fish-oil soap with Pickering (A) containing 0.38 per 

 cent of copper did not affect the caustic properties of the spray. 



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