342 The Principles of Fruit-growing 



The standard fungicides for spraying purposes are bordeaux 

 mixture and lime-sulfur. The lime-sulfur has already been dis- 

 cussed; we may now take up the preparation of bordeaux. 



Bordeaux mixture is a bluish green copper compound that settles 

 out when freshly slaked lime and a solution of copper sulfate (blue- 

 stone) are mixed. Many formulas have been recommended and used. 

 The 5-5-50 formula may be regarded as standard. In such a formula 

 the first figure refers to the number of pounds of copper sulfate, the 

 second to the stone or hydrated lime, and the third to the number of 

 gallons of water. Bordeaux must often be used as weak as 2-2-50, 

 on account of injury to some plants. 



To make fifty gallons of bordeaux mixture, proceed as follows: 



(1) Pulverize five pounds of copper sulfate (blue-stone), place 

 in a glass, wooden or brass vessel, and add two or three gallons of 

 hot water. In another vessel slake five pounds of quicklime in a 

 small amount of water. When the copper sulfate is all dissolved, 

 pour into a barrel and add water to make forty to forty-five gallons. 

 Now strain the lime into this, using a sieve fifty meshes to the inch 

 or a piece of cheese-cloth supported by ordinary screening. Stir 

 thoroughly, and add water to the fifty-gallon mark. The flocculenfc 

 substance which settles is the effective fungicide. Always stir 

 vigorously before filling the sprayer. Never add the strong lime 

 to strong vitriol. Always add a large amount of water to one or 

 the other first. Copper sulfate used alone would not only wash off 

 quickly in a rain, but cause a severe burning of fruit and foliage. 

 Lime is added to neutralize this burning effect of the copper. If the 

 lime were absolutely pure, only slightly more than one pound would 

 be required to neutralize this burning effect. For many purposes 

 an excess of lime is not objectionable and may be desirable. For 

 nearly ripe fruit and ornamentals an excess of lime augments spotting. 

 In such cases the least amount of lime possible should be used. 

 Determine this by applying the cyanide test (2). 



(2) Secure from the druggist 10 cents' worth of potassium 

 ferrocyanide (yellow prussiate of potash) and dissolve it in water 

 in an eight-ounce bottle. Cut a V-shaped slit in one side of the cork, 

 so that a few drops of the liquid can be obtained. Now proceed as 

 before. Add lime with constant stirring until a drop of the ferro- 

 cyanide ceases to give a reddish brown color. 



(3) When bordeaux mixture is desired in large quantities, stock 

 solutions should be made. Place one hundred pounds of copper 



