THE PRINCIPLES OF DISEASE CONTROL 89 



very strong solutions may be employed. The strength of solu- 

 tion now generally regarded as a standard consists of : 



Copper sulfate ... ... 5 lb. 



Stone lime 5 lb. 



Water 50 gal. 



A mixture of this strength is known as the 5-5-50 formula. 

 The strength may be decreased or increased as desired, and it will 

 be expressed in a similar manner, thus 2-2-50 and 10-10-50 

 respectively refer to 2 pounds of each chemical and to 10 pounds 

 of each in 50 gallons of water. The method of making Bordeaux 

 consists in dissolving the required amount of copper sulfate in 

 an equal number of gallons of water, the copper sulfate being 

 placed in a sack and suspended in a barrel or other vessel, this 

 method greatly facilitating the solution. 



The amount of lime required may be slowly slaked in another 

 barrel or vessel and then brought up to a thick milk with a known 

 quantity of water. This solution may be used as a stock solution, 

 1 gallon of the copper sulfate representing 1 pound of the copper 

 salt, and 1 gallon of the lime milk representing 1 pound or more 

 according as the mixture has been prepared. The amount of the 

 copper solution for a barrel or tank may then be diluted practically 

 to the capacity of the vessel employed, and then the fairly diluted 

 lime milk is poured in, stirring constantly. It is desirable that the 

 latter should be strained. The strong stock solutions should not 

 be poured together. 



Ammoniacal copper carbonate. This preparation is frequently 

 employed where a strong fungicide is needed, and where the 

 color of the Bordeaux mixture renders it objectionable, the am- 

 moniacal solution discoloring foliage to only a very slight extent. 

 The constituents of this mixture are as follows : 



Copper carbonate 5 oz. 



Ammonia (26 Baume") 3 pt 



Water 5° g al - 



The strong ammonia, which one must handle carefully, may be 

 diluted to about five times its volume, and the copper carbonate 

 may be rubbed up with water in a small vessel to form a thin 

 paste. This paste is added to the now dilute ammonia with 



