218 The Potato 



tions are taken from the New York Cornell Agricultural 

 Experiment Station, Circ. 19, 1913. 



The best bordeaux mixture is made by mixing a dilute 

 solution of copper sulphate (blue vitrol) with a dilute milk- 

 of-lime. The mixture may be made of various strengths 

 by using different amounts of copper sulphate and lime to 

 a given amount of water. A combination of 3 pounds 

 of copper sulphate and 3 pounds of lime to 50 gallons 

 of water is probably strong enough to control the blight, 

 but because of the stimulating action of bordeaux mixture 

 on the potato plant, a strength of 5 pounds each of 

 copper sulphate and lime to 50 gallons of water is usually 

 recommended. This is indicated by the formula 5 : 5 : 50. 

 In order to make the bordeaux mixture of any strength, 

 the procedure should be as follows : — 



A stock solution of copper sulphate should be made in a 

 barrel from 45 pounds of copper sulphate dissolved in 45 

 gallons of water. A gallon of the solution will then con- 

 tain about one pound of copper sulphate. If the crystals, 

 placed in a gunny sack, are suspended so as to be slightly 

 beneath the surface of the water, they will dissolve in 

 three or four hours. 



A stock mixture of lime should be made from a bushel 

 of good stone lime placed in a barrel and slaked by the 

 gradual addition of water. Care must be taken not to 

 "drown" the lime, ^^^^en it has become pulverized by 

 the slaking, water is added to make a paste, and then 

 enough more water may be added to make 45 gallons. 

 This should not be allowed to dry out. Hydrated lime 

 (which is already slaked) may be used in place of stone 

 lime, but air-slaked lime should never be used. 



Another barrel or larger container or even the sprayer 

 tank itself may be used for mixing the bordeaux. What- 



