196 SPRAYING MATERIALS 



But for that purpose, particularly for use against the brown rot 

 of stone fruits, it is very efficient. 

 The usual formula is as follows : 



8 pounds sulfur, 8 pounds rock lime, 50 gallons water. 



An old oil cask is a good receptacle in which to prepare it. 

 The lime is placed in the bottom of the cask, and it is imperative 

 that it be good, hard rock lime and not air-slacked lime, since 

 the heat for cooking is to come entirely from the lime. On top 

 of the lime place the sulfur. Then add hot water slowly until 

 the lime is slacked, stirring carefully, as needed, to prevent the 

 "burning" of the lime. After slacking is complete allow the 

 mixture to stand and cook for from ten to fifteen minutes, depend- 

 ing on the amount of heat generated by the lime, keeping the 

 barrel covered Avith an old burlap to keep in the heat. Then 

 add enough water to make 50 gallons, strain into the spraying 

 cask and apply at once. Remember this is merely a summer 

 fungicide and has no value for San Jose scale and relatively 

 little as a dormant fungicide. 



Dry Forms of Sulfur Compounds. — At the present time the 

 most interesting of the special forms of sulfur on the market are 

 the dry forms in combination with other substances such as 

 calcium, sodium and barium. They come as powders of varying 

 degrees of fineness and dissolve fairly readily in water. Some 

 of them are very promising and of course all have the advantage 

 over the liquid forms that they eliminate expense in handling. 

 If further experiments shall show they are efficient under all con- 

 ditions and do not injure foliage they ought to prove of value, 



** Atomic sulfur " is another form. This is a very finely 

 divided paste form of pure sulfur which seems promising, but 

 at the present writing needs further testing, 



INSECTICIDES 



There are two general classes of insecticides : The food-poisons, 

 used for chewing insects and of usually some form of arsenic ; 

 and the contact spray used for sucking insects. 



