260 ANNUAL, REPOKT OF THE Off. Doc. 



THE NUESERY PROBLEM. 



The agency of nurseries as distributors of insect pests has been 

 elsewhere dwelt upon. The methods to be adopted to prevent this 

 distribution are matters of control by the State authorities and not 

 within the scope of this article. 



Experiments have shown that so far as the pernicious scale is con- 

 cerned, stock may be thoroughly cleared of it by careful fumigation 

 with hydrocyanic acid gas. As this destroys also many other fruit 

 pests, it is not an unreasonable requirement that nurserymen should 

 fumigate all their fruit stock before sending it out. 



Fumigation as here used, means exposing the dormant stock to 

 the action of the gas in a properly constructed room or building, for 

 a time sufficiently long to kill the pernicious scale. 



A properly constructed room or house is one that is gas tight. It 

 is best made of wood, may be of any desired size or shape, should 

 have double walls with building paper between, should be ceiled with 

 tOEgued and grooved stuff closely fitted and should have closely fitted 

 doors and one window to be closed and opened from without. There 

 need be no flooring; but unless the stock is fumigated on a wagon 

 backed into the house, there should be a slat floor a foot above the 

 ground. In the center there should be a place for the gas generator 

 which may rest upon the ground. If a wagon is used, the generator 

 may go under the wagon. The space below the slat floor is to allow 

 the diffusion of the gas in every direction. The stock should not be 

 packed too tightly and should be so arranged that toward each corner 

 there should be a tolerably open chimney or passage through which 

 the gas may get to the ceiling. 



The formula for each 100 cubic space is: 



Cyanide of potassium, 98 per cent, pure, by weight, 1 oz. 



Sulphuric acid, sp. gr. 1.83, by measure, 2 oz. 



Water, 4 oz. 



Pour the acid slowly into the water and when everything is ready, 

 drop the cyanide, broken into small lumps, into the mixture. In a 

 small house, the cyanide in a paper bag can be dropped by hand into 

 the jar and before this bag is penetrated the operator can get out and 

 close the doors. . In a large house, wdth considerable stock, the bag 

 of cyanide may be suspended over the jar by a string, attached near 

 the doors. When the doors are ready to close, release the cord that 

 the bag of cyanide may drop into the dilute acid and close the doors 



