New York Agricultural Experiment Station. 457 



The lye should be dissolved in boiling water and the fish oil at 

 once added. This mixture should be kept boiling for two hours 

 and then allowed to cool. This soap should be used at a strength 

 of one pound to one gallon of water. 



Pure kerosene oil has been used as a winter application with 

 varying degrees of success. It will kill all the scales with which 

 it comes in contact, but unless the tree is very hardy or the con- 

 ditions are just right it is liable to kill the tree also. It should 

 not be used except in extreme cases. 



When the trees or nursery stock are to be fumigated with 

 hydocyanic acid gas, the gas may be generated after the follow- 

 ing formula: 



Fused cyanide of potassium (98 pel' cent) 1 oz. 



Sulphuric acid, commercial 1 oz. 



Water 3 ozs. 



Pour the water and the sulphuric acid into a glass or glazed 

 earthenware dish. When this is placed where it is to remain 

 add the cyanide of potassium. This will generate enough gas for 

 150 cubic feet of space. Much care should be taken that the 

 operator does not breathe any of the fumes. 



Fumigation is not considered the most practical method of 

 treatment for infested orchard trees here in the east, but it maj 

 be used for infested nursery stock. On another page reference 

 is made to treating nursery stock in large cellars. A convenient 

 house for fumigating a small amount of nursery stock is shown 

 at Plate XXII. These may be built any convenient size. They 

 are built of a double thickness of boards with building paper be- 

 tween to make them as nearly air tight as can be conveniently 

 done. The door is made to fit very tight. The stock is piled in 

 the house in such a manner as to allow the gas to circulate freely. 

 One generator with enough material to fill the space is placed 

 about the middle of the floor and as soon as the cyanide is added, 

 the door is shut and the stock left for an hour. When the fumi- 

 gating is done on a cool, cloudy day or at night, there is practi- 

 cally no danger of injuring the stock as shown by the fact that 

 various varieties of fruit trees, also currants and gooseberries, 



