CHAPTER X. 



NATURE AND SOURCE OF THE SPRAYING MATERIALS USED. 



The following notes on the ehemicals for sprays arc presented for 

 the general information of the fruit grower. The facts given are 

 those which every sprayer should understand. 



Spraying is frequently retarded or prevented owing to a want of 

 information relative to the nature, sources of supply, or true value of 

 the chemicals required. A grower uninformed upon the last-named 

 point is often at the mercy of local druggists or other dealers. For 

 examph^, copper carbonate can l)e made by the grower himself at from 

 13 to 14 cents per pound, and ammonia of 20° strength may be pur- 

 chased at about 60 cents per gallon, while local prices have been 

 knoMii to range as high as !!^l per pound for copper carbonate and 

 $1.50 per gallon for ammonia, which makes it impossil)le to undertake 

 spray work. The writer has found the same conditions prevailing in 

 respect to prices for sulphur, which is used very largeh in the sulphur 

 sprays and for the treatment of nuldew. In some cases tlie prices 

 asked by dealers in the East have been 100 or 500 per cent higher 

 than growers have for years been pa3nng in California. It can 

 not be expected that the sulphur sprays will be generally used in the 

 East under such conditions. 



COPPER stTLPHATE (formula CuSO^SHaO). 



Of all fungicides thus far known, copper sulphate is the most 

 important. It is counuonly known as blue vitriol or bluestone in the 

 United States. Its foreign names are largely equivalents of these 

 terms, although the Germans also apph' the name of copper vitriol 

 {Knpfervitriol). 



When pure, copper sulphate crystallizes in large, blue, triclinic 

 prisms. It contains about 25.3 per cent of copper, and dissolves in 

 four parts of cold water and two parts of boiling water. 



The presence of iron is indicated by a greenish color of the crystals 

 or at the surface of a watery solution when exposed to the air. A 

 solution of pure copper sulphate should be blue. The presence of a 

 small amount of iron, which commonly occurs when copper sulphate 

 is manufactured as a b3^-product in modern smelting works, does not 

 necessarily detract from its value as a fungicide, while this b3^-product 



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