224 FRUIT CULTURE. 



causes the mixture to adhere, and also acts 

 chemically upon the copper. Hence the value 

 of the mixture. But the lime is objectionable 

 on account of the stain to the foliage, and also 

 because of the clogging. Another formula is 

 recommended by the United States Depart- 

 ment of Agriculture, increasing the propor- 

 tion of sulphate of copper, and also the amount 

 of water, but diminishing the proportion of 

 lime, as follows : Dissolve twelve pounds of 

 sulphate of copper in fifteen or twenty gallons 

 of water. In another vessel make a milk of 

 lime with eight pounds of lime in ten or twelve 

 gallons of water. Strain and mix in a barrel, 

 adding at least fifteen gallons of water. 

 There is a growing tendency to increase the 

 copper and diminish the proportion of lime. 



Sulphate of Copper (blue vitriol). — This is 

 undoubtedly the efficient element in destroy- 

 ing mildew. When used without the lime it 

 is more liable to injure foliage. It does not 

 adhere as well, and it may be doubted whether 

 it is as efficient. Still it is so much more easily 

 applied, and without staining the foliage, that 

 it may be used with care. One pound of the 

 sulphate is sufficient for twenty-five gallons of 

 water. As a wash or a spray for trees and 

 vines in early spring, it may be used much 



