EXPERIMENT STATION BULLETINS. 329 



mixture remains hot for fifteen or twenty minutes after the slaking is 

 completed, some sulphur will go into solution and injury to the foliage 

 may result. 



The time of adding the cold water to stop the boiling depends upon 

 the lime. With a sluggish lime all the heat in it may be needed, while 

 with limes that become intensely hot, care must be taken not to allow 

 the boiling to proceed too far. 



BORDEAUX MIXTURE. 



Bordeaux mixture is the standard spraying mixture used to protect 

 plants from such fungous diseases as apple and pear scab, grape-rot, leaf 

 spots, mildews, potato blight, etc. There are but three things used 

 in its preparation, — water, lime and copper sulphate. The water acts 

 as a carrier, the lime neutralizes the caustic action of the copper sulphate 

 and also makes the mixture stick to whatever it is sprayed upon, and 

 the copper sulphate is the chemical that prevents the growth of the spore 

 of the disease. 



These three substances are combined in various proportions, depend- 

 ing upon the kind of plant to be treated. For apples, pears, cherries and 

 plums (except the Japanese varieties) the preparation is usually four 

 pounds of copper sulphate, with about the same amount of lime, to fifty 

 gallons of water. Poison is added as needed. The copper sulphate will 

 readily dissolve in two gallons of hot water, to which should be added 

 enough water to make twenty-five gallons or one-half barrel. Do not use 

 an iron or tin vessel to dissolve this in, as the copper sulphate will de- 

 stroy it, and besides the iron will spoil the Bordeaux. A wooden pail 

 is good. Slake the lime into a thin paste and add water to make twenty- 

 five gallons. Pour, or let these run together into a third barrel, and the 

 Bordeaux is made. When it is emptied into the spray barrel or tank, it 

 should be strained through a brass wire strainer to catch any of the 

 coarse particles. 



Whenever it is necessary to use a quantity of the mixture, it is de- 

 sirable to have the lime and the copper sulphate in ''stock solutions." 

 A quantity of lime is slaked to a paste and held so by being covered with 

 water. The copper sulphate, say fifty pounds, is placed in a clean gunny 

 sack and suspended in a barrel (one with wood hoops is much to be pre- 

 ferred) containing twenty-five gallons of water. This will dissolve in 

 about a day. One gallon of this "stock solution"* is equal to two pounds 

 of copper sulphate. 



A good quick way to combine these three substances is as follows: 

 Put the amount of the "stock solution" of copper sulphate required in 

 a barrel, and add enough water to make 25 gallons, or one-half barrel. 

 Put about 7 pounds of the lime paste in a barrel and add 25 gallons of 

 water, making a thin whitewash. Pour, or let these two run together 

 into a third barrel, or directly into the spray barrel or tank, being sure 

 to strain. When partly run in, test with ferro-cyanide of potashf to 



♦Always stir this "stock solution" before dipping any out, in order that what is used 

 may be full strength. 



fThis chemical can be secured of any druggist. Ten cents worth dissolved in a pint of 

 water will be enough for a season. Drop a very little in the bordeaux, if a reddish brown 

 color appears more lime must be added. If there is no discoloration, there is enough 

 lime. 



