ONIAN INSTITUTION LIBRARIES 
All nursery stock which is under the least suspicion of contamination 
with the San Jose scale should be fumigated; and it is perhaps worth 
while to fumigate in any case to give the utmost assurance of safety to 
the purchaser. The hydrocyanic-acid-gas fumigation is the one to use. 
This gas is generated by combining monies cyanide, sulphuric acid, 
and water. The proportions of the chemicals are as follows: Refined 
potassium cyanide (98 per cent), 1 ounce; commercial sulphuric acid, 
1 ounce; water, 3 fluid ounces—to every 100 cubic feet of space in the 
fumigating room or house. The latter should be as nearly air-tight as 
possible and provided with means of ventilation above and at the side, 
operated from without, so that at the end of the treatment the poison- 
ous gases can be allowed to escape without the necessity of anyone 
entering the chamber. The generator of the gas may be any glazed 
earthenware vessel of 1 or 2 gallons capacity, and should be placed 
on the floor of the fumigating room and the water and acid necessary 
to generate the gas added to it. The cyanide should be added last, 
preferably in lumps the size of a walnut. Promptly after adding the 
cyanide the room should be vacated and the door made fast. The 
treatment should continue forty minutes. It must be borne in mind 
that the gas is extremely poisonous and must under no circumstances 
be inhaled. The gas treatment is effective against the scale on grow- 
ing trees in the orchard also; but the difficulty and expense of the 
treatment, except for nursery stock, make it prohibitive in the case of 
deciduous fruits. 
WI 
3 9088 01272 701 
FUMIGATION OF NURSERY STOCK. 
Approved: 
JAMES WILSON, 
Secretary of Agriculture. 
WasuHineton, D. C., March 10, 1906. 
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