FORMULAS FOR SPRAY MIXTURES 91 



Bordeaux mixture may be made of different strengths for 

 spraying different plants, but a common strength is four pounds 

 of Ume, four pounds of copper sulfate and fifty gallons of water. 

 If large quantities are to be used, it is better to make stock solu- 

 tions of copper sulfate and of lime than to prepare separate lots 

 each time a barrel of spraying material is needed. If the stock 

 solutions are made by using one pound of copper sulfate or of 

 lime to each gallon of water, it is only necessary to measure out 

 four gallons of each stock solution to get the required amounts to 

 make fifty gallons of Bordeaux mixture. The stock solutions 

 should be kept in wooden vessels, and should be stirred thoroughly 

 just before any of the material is measured out, in order to insure 

 getting material of uniform strength. The stock solutions will 

 keep indefinitely, if covered to prevent evaporation; but the 

 Bordeaux mixture should be used the day it is made. 



Paris green is purchased in the form of a dry powder. It 

 may be applied as a simple mixture wdth water, but since it is 

 likely to contain soluble arsenic which is injurious to foliage, a 

 safer plan is to add a small quantity of slaked lime to the mixture 

 of Paris green and water. This combines with any arsenic that 

 may dissolve in the water, and makes the mixture much safer 

 to apply to the foliage. Equal quantities of Paris green and lime 

 make a safe mixture, though more lime is often used. In mixing 

 Paris green with water, it should first be made into a thin paste 

 with a small quantity of water. This insures a smooth mixture 

 free from lumps. When lime is to be used with the Paris green 

 it is a good plan to dilute the slaked lime with water to almost 

 the full volume of the spray mixture to be made; then stir in the 

 Paris green, which has previously been made into a paste with a 

 small quantity of water as already suggested. Paris green is 

 used at different strengths, but four ounces to fifty gallons of 

 water is a very common strength. Sometimes as much as eight 

 ounces to fifty gallons is used for spraying potatoes for the control 

 of the Colorado potato beetle. 



Arsenate of lead is usually purchased in paste form, though 

 there are now powdered forms offered on the market, and it is 

 also possible to make this material at home by combining solu- 

 tions of arsenate of soda and acetate of lead. If the paste form 

 is used, it must be worked up with a small quantity of water 

 until a smooth, homogeneous mixture is obtained. This is then 

 gradually diluted to the desired volume. A common strength of 



