CALIFORNIA CITRUS CULTURE. 65 



SPRAYS. 



For many years spraying was the only known method for the control 

 of citrus pests, but the discovery of fumigation and the use of hydro- 

 cyanic gases has practically eliminated commercial spraying in the 

 citrus orchards for injurious insects. Fungus diseases, however, are 

 still to be controlled by spraying, including such fungicides as Bordeaux 

 mixture and lime-sulphur. 



Plant lice are controlled entirely by the use of contact sprays, chief 

 of which are carbolic acid emulsion and tobacco decoction. 



In a number of instances it has been found practical to control certain 

 scale insects by the use of sprays. Young seed bed stock is usually 

 dipped in resin wash or sprayed with an oil emulsion to kill young 

 scale. It has been found that the carbolic acid emulsion is a cheap and 

 ready means of controlling the citrus mealy bug. 



Only the most important spray formulae are given in this work : 



Bordeaux Mixture, 



Unslaked lime 4 pounds 



Copper sulphate (bluestone) 4 pounds 



Water 50 gallons 



The task of mixing these chemicals, where large quantities of the 

 spray is used, is no small thing in itself. A great deal of study has 

 been given to the construction of suitable mixing apparatus. 



The first consideration is to get the materials high enough on a plat- 

 form so that they can be easily and rapidly placed in the spraying 

 tanks of the power machines. This is done by constructing at convenient 

 places in the orchard, platforms large enough to hold a large box for 

 slaking lime, a lime solution agitator, and a vat for dissolving bluestone. 

 Such a platform is about 12 feet square and 4J feet high. A large 

 standpipe for filling the tanks is desirable, or the water must be pumped 

 into the tank while the solutions are being added. 



The lime is first slaked in a common vat for that purpose. It is 

 necessary to keep the slaked lime agitated properly when it is being 

 drawn off to mix with the bluestone in the spraying tank. 



The bluestone vat contains slats, across the entire box or simply 

 across one end. These slats must be low enough so that the bluestone, 

 which is placed upon them in sacks, will be completely immersed in the 

 water. This method admits quick dissolving of the bluestone, much 

 more rapidly than if simply poured into the tank and stirred. 



The lime and bluestone are mixed with a given amount of water so 

 that the proper quantities of the resultant solutions can be measured 

 ,so as to give the mixture the strength of the above formula. 

 5 cc 



