EXPERIMENT STATION BULLETINS. 395 



FORMULAS. 



, BORDEAUX MIXTURES. 



"Normal," or the 1 to 10 formula: 



Copper sulphate 4 pounds 



Quick lime 4 



Water 40 gallons 



The amount of water may be varied from 40 to 50 gallons, while for peaches 

 60 gallons of water should be used. The amount of lime may also be slightly 

 increased, if the mixture shows a tendency to burn the foliage or roughen the 

 fruit. 



Preparation. — The copper sulphate may be dissolved by means of hot water 

 and then diluted in the proportion of two gallons of water to one pound of salt. 

 In preparing large amounts it is customary to place the copper sulphate in a 

 coarse sack which is then suspended in the upper part of a barrel of water and 

 left until dissolved. 



The lime should be fresh quicklime. If this cannot be obtained double the 

 amount of air slaked lime may be used but it is not considered so good and 

 cannot be recommended. Slake the lime in the usual manner as in the prepara- 

 tion of whitewash, adding water slowly. This should then be diluted with water, 

 after previous straining through a fine sieve or piece of coarse sacking. The 

 two solutions are now to be mixed under constant stirring, while pouring the two 

 liquids together, after which water is to be added to make the full amount. The 

 more dilute the solutions are when mixed the finer will be the resulting precipi- 

 tate. On the other hand, if the copper solution and the lime are concentrated, 

 the precipitate will be coarse and heavy and is apt to clog the spraying machinery. 

 Furthermore, the mixture when prepared with strong solutions requires more 

 constant stirring during use • to prevent settling and consequent unevenness of 

 application. A stock" solution of the copper sulphate may be made of known 

 strength (i. e. one pound to the gallon), and kept in closed vessels and diluted 

 when wanted. The lime may also be slaked in large amounts and if covered 

 with water will keep for a considerable period. 



The proportions of copper sulphate and lime as given, ordinarily produce a 

 mixture which is slightly alkaline and consequently harmless to the foliage of 

 plants. It is safest, however, to test the mixture before using it to make sure 

 that the acid of the copper sulphate has been entirely neutralized by the lime. 

 A reliable test consists in the use of the yellow prussiate of potash (ferro- 

 cyanide of potassium) which may be purchased at any drug store. One ounce 

 of this salt dissolved in half a pint of water will constitute the test solution. To 

 apply the test a little of the Bordeaux mixture is put in a white dish and a few 

 drops of the ferro-cyanide solution added. If a brown discoloration results more 

 of the lime milk is to be added to the mixture until the test solution remains 

 colorless when applied. Another test consists in dipping a clean piece of polished 

 iron or steel, as a knife blade, into the mixture for one minute, when a delicate 

 coating of metallic copper will be deposited on the iron if there is not enough 

 lime present. A piece of red litmus paper may also be used by dipping it into 

 the mitxure, if it remains red more lime is necessary while if it becomes blue 

 the mixture is alkaline and may be safely used. 



BORDEAUX MIXTURE WITH PARIS GREEN. 



Paris green, which is the most common material for combating the codling 

 moth and other leaf and fruit-eating insects may be combined with Bordeaux 

 mixture thus reducing the labor and expense in spraying for both fungi and 

 insects. (See Mich. Exp. Sta. Bui. No. 224.) It may be used at the rate of 

 one pound to 200 gallons of the mixture. 



SODA-BORDEAUX ; HYDRATE. 



Babbit's Potash or Lye or Lewis' Lye — Soda 1 "pound" can 



Copper sulphate 3 pounds 



Lime 5 ounces 



Water 30 gallons 



