INSECTICIDES 49 



" This concentrate will keep with little change, unless the 

 weather is below 5 F., if stored in filled, stoppered barrels. 

 Even in open receptacles there will be no loss if the surface be 

 covered by a layer of oil to prevent access of air. Each boiling 

 should be tested with a Beaume hydrometer* and its density 

 marked on the barrels or other containers." 



The dilution is based upon the specific gravity as shown ^by 

 the hydrometer and may be safely made according to the out- 

 line in the above table. 



In making this mixture it is important that only high-grade, 

 pure lime should be used, and lime with less than 90 per cent 

 calcium oxid (CaO) should be discarded. 



8. Self-boiled Lime-sulfur. Self-boiled lime-sulfur has proven 

 to be the only safe fungicide for the foliage diseases of the 

 peach and stone fruits, and is used extensively as a summer spray 

 on pome fruits. As a winter wash for San Jose scale it has not 

 proven effective, but when used as a summer spray for fungous 

 diseases it has some considerable insecticidal value. This mixture 

 has been developed chiefly by the work of Mr. W. M. Scott 

 formerly of the United States Department of Agriculture, from 

 whose latest bulletin! the following is quoted: 



" In order to secure the best action from the lime, the mix- 

 ture should be prepared in rather large quantities, at least enough 

 for 200 gallons of spray, using 32 pounds of lime and 32 pounds 

 of sulfur. The lime should be placed in a barrel and enough water 

 (about 6 gallons) poured on to almost cover it. As soon as the 

 lime begins to slake the sulfur should be added, after first running 

 it through a sieve to break up the lumps, if any are present. 

 The mixture should be constantly stirred and more water (3 or 

 4 gallons) added as needed to form at first a thick paste and then 

 gradually a thin paste. The lime will supply enough heat to 

 boil the mixture several minutes. As soon as it is well slaked 

 water should be added to cool the mixture and prevent further 

 cooking. It is then ready to be strained into the spray tank, 

 diluted, and applied. 



" The stage at which cold water should be poured on to stop 



* These hydrometers, made specially for testing lime-sulfur mixture, may 

 be obtained from the Bausch & Lomb Optical Co., Rochester, N. Y., and 

 other dealers in laboratory glassware. 



t Farmers' Bulletin, 440, U. S. Dept. of Agr., p. 34. 



