Control Measures 219 



ever container is used should be filled three-fourths full 

 of water. If a 5 : 5 : 50 solution is desired, 5 gallons of 

 copper sulphate stock solution should be added to this 

 water for every 50 gallons of mixture to be made. The 

 solution requires stirring until it is well diluted, after 

 which 5 gallons of the stock mixture of milk-of-lime should 

 be added to each 50 gallons of mixture. The lime-water 

 should be run through a strainer in order to prevent the 

 larger particles of lime from getting into the sprayer tank. 

 While the milk-of-lime is being added to the dilute copper 

 sulphate solution in the sprayer tank, the material in the 

 container should be stirred constantly. The sky-blue 

 bordeaux mixture will result. Enough water to make the 

 required amount of mixture must be added to it. 



It is often more convenient, although not necessary, to 

 make the bordeaux on an elevated platform so as to allow 

 the mixture to run by gravity into the sprayer tank (see 

 Plate XIII). When such a platform is provided, it is easily 

 possible to dilute both the stock copper sulphate solution 

 and the stock lime solution in separate containers before 

 mixing them by allowing them to run together. This 

 method makes a bordeaux that stays in suspension a little 

 better than that made by diluting but one stock before 

 mixing. In case the latter method is used the required 

 amount of stock in each case should be diluted with one- 

 half the amount of water necessary to make the mixture. 



The mixture should now be tested with a few drops 

 of a solution of potassium ferrocyanide. This is made 

 from crystals of potassium ferrocyanide dissolved in soft 

 water. Five cents' worth of crystals dissolved in a pint of 

 water will provide enough of the solution to last through- 

 out the season. Should a brown precipitate result when 

 a few drops of this solution are added to the bordeaux 



