FUMIGATION OF NURSERY STOCK * 



S. A. Beach. 



INTRODUCTION. 



The best known way of killing San Jos(5 scale on dormant nurs- 

 ery stock is by fumigation with hydrocyanic acid gas.^ This 

 treatment is valuable not only against San Jos^ scale but against 

 all scale insects which do not winter in the egg stage. It will 

 doubtless also check the spread of some other kinds of injurious 

 insects which are liable to be distributed on nursery stock. 



Plain directions for fumigating dormant nursery stock with 

 hydrocyanic acid gas will first be given, after which suggestions 

 will be made as to the location and construction of fumigation 

 houses or chambers. 



APPARATUS, MATERIALS AND METHOD. 



THE EQUIPMENT. 



The things needed for fumigating nursery stock with hydro- 

 cyanic acid gas are: (1) The chemicals; (2) a suitable dish in 

 which to mix them; and (3) an air-tight box or chamber to hold 

 the stock while it is being fumigated. 



CAREFUL WORKMEN NEEDED. 



It is not hard to kill the San Jos6 scale; the difficulty is to kill 

 it without injuring the plant upon which it is living. The scale 

 insect is fastened immovably to the plant with its mouth parts 

 stuck into the bark so that it may suck the plant juices which 

 constitute its food. It cannot be given poison in its food, but 

 must be killed by something which comes in contact with its 



* Reprint of Bulletin No. 174, 



'This substance is commonly known, in liquid foa-m by the name "prussic 

 acid." 



