76 REMEDIES FOR THE CANKER-WORM 



of water, with a pound or two of fresh slacked lime added to 

 each barrel of the mixture to render all the arsenic insoluble, 

 and thus prevent injury to the foliage. 



If arsenate of lead is used it should be bougfht in the form of 

 a paste, and may be used at the rate of three pounds to fifty 

 gallons of water. This poison has these advantages over 

 Paris green : (i) There is no danger of burning the leaves, so 

 that it can be put on in stronger mixture; (2) it remains in 

 suspension in the water better ; (3) it adheres to the foliage 

 more evenly and longer ; (4) it may be seen upon the leaves 

 more readily so that the thoroughness of the spraying may 

 more easily be determined. 



Scheele's green is another arsenical insecticide recently 

 placed on the market. According to a bulletin of the United 

 States Department of Agriculture, it " is similar to Paris 

 green in color, and differs from it only in lacking acetic acid ; 

 in other words, it is a simple arsenite of copper. It is a much 

 finer powder than Paris green, and therefore more easily kept 

 in suspension, and has the additional advantage of costing only 

 about half as much per pound. When properly washed and 

 prepared by the manufacturers it is less harmful to the foliage 

 even than Paris green, is quicker in effect, and should sup- 

 plant the latter as an insecticide. It is used in the same wav 

 and at about the same strength as Paris green." 



COST OF THE CHEMICALS 



Arsenate of lead costs from fifteen to twenty cents a pound, 

 according to quantity purchased. Scheele's green costs about 

 ten cents a pound, and Paris green about twenty cents a 

 pound. All of these substances may be purchased through 

 dealers in insectides, the large drug firms, the seed houses, or 

 of the manufacturers of chemicals. 



There are many sorts of good spraying pumps now upon 

 the market ; they may be purchased through any hardware 

 dealer or seedsman. The spray should be applied through a 

 nozzle that throws a fine mist, and should be evenly distributed 

 over the tree, stoj^ping just before the leaves begin to drip. 



