1892.] PUBLIC DOCUMENT — No. 33. 237 



But the fact cannot be too strongly emphasized that 

 everything depends upon how they are prepared, and upon 

 how and when they are applied. The following pages at- 

 tempt to give somewhat full instruction how to prepare and 

 apply the most valuable fungicides, and such general hints 

 when to apply them, as will be of service. The proper 

 times for their application vary so much with special con- 

 ditions, however, that instructions on this point must form 

 an important part of the special directions for any particular 

 case. 



Preparation. — The protective quality of most of the best 

 fungicides lies in the fact that they contain a certain propor- 

 tion of copper ; and, of the four recommended as applicable 

 to most cases of fungous diseases, three contain it as the 

 essential constituent. 



The Bordeaux Mixture requires six pounds sulphate of 

 copper, four pounds quicklime (fresh) and twenty-two gal- 

 lons water. The sulphate of copper, known to the trade 

 also as blue vitriol or blue-stone, is dissolved in two gallons 

 of water. The solution will be hastened if the water be 

 heated and the sulphate pulverized. After the solution is 

 complete, fourteen gallons of water are added to it. The 

 quicklime is slaked in six gallons of water, and stirred 

 thoroughly until it forms a smooth, even mixture. After 

 standing for a short time it is again stirred and added 

 gradually to the sulphate solution, which is thoroughly 

 stirred meanwhile. The mixture is then ready for use, 

 though some experimenters recommend further dilution to 

 twenty-five or thirty gallons, for certain uses. It should 

 not be prepared until needed, and should be used fresh, 

 as it deteriorates with keeping. Since the lime remains 

 merely in suspension and is not dissolved, the mixture 

 should be strained through fine gauze before entering the 

 tank of the spraying machine, so that all of the larger 

 particles which might clog the sprayer may be removed. 



Ammoniacal carbonate of copper, in its improved form, 

 is prepared from three ounces carbonate of copper, one 

 pound carbonate of ammonia and fifty gallons water. Mix 

 the carbonate of copper with the carbonate of ammonia, 

 pulverized, and dissolve the mixture in two quarts of hot 



