INSECTICIDES, FUNGICIDES, AND SPRAYING 207 



the owner of a few trees nothing better could be recom- 

 mended. For extensive spraying the use of miscible oils 

 will usually be found advisable also. The time and labor 

 necessary to prepare the oil emulsions bring their cost up to 

 an amount equal to or greater than that of the soluble oils. 

 Vapors. The vapor of bisulfid of carbon is used in kill- 

 ing borers. The liquid is injected into the burrow with 

 an oil -can or syringe, and the opening plugged with putty. 

 The fumes given off by the carbon bisulfid are fatal to 

 all insects that breathe it. Carbon bisulfid is very inflam- 

 mable. 



FUNGICIDES 



Fungicides act as preventives of plant disease by ob- 

 structing the germination of the spores of the fungi causing 

 such disease. If the leaves of trees, for example, are cov- 

 ered with a coating of copper sulfate or other chemical 

 deleterious to the germination of the spores, the reproduc- 

 tion of the fungi is held in check and disease prevented. 



Bordeaux Mixture. This is the standard fungicide and 

 consists of a combination of copper sulfate, fresh lime, and 

 water. The formula in most general use is the following : 



Copper sulfate 4 lbs. 



Fresh lime 4 lbs. 



Water to make 50 gals. 



By combining the copper and the lime it is found that the 

 copper sulfate may be used more freely and with less in- 

 jury than if used alone, and it will adhere a long time to the 

 foliage. For preparing this fungicide on a small scale, the 

 copper sulfate should be dissolved in twenty-five gallons of 

 water, using a half barrel for the purpose. To dissolve the 

 copper sulfate readily, it should be placed in a coarse cloth 



