244 FUMIGATION METHODS 



the most effectual method we have to clean up nursery 

 stock of its insect pests, and has given great satisfaction 

 where it has been judiciously handled. There are 

 cases in which the exposure to the gas was unneces- 

 sarily long, resulting in marked injury to the trees. 

 It is useless, of course, to subject trees to the gas which 

 are free from insects. The gas treatment should find 

 favor in warehouses, flour-mills, etc., where vermin 

 are to be destroyed and no life is at stake, but I have 

 met with no experience in such places. I cannot 

 recommend it for conservatories or greenhouses where 

 a mixed lot of plants are grown. In my own experi- 

 ence I have found many kinds of plants suffer greatly 

 in an exposure that is too weak and brief to kill all of 

 the red spiders or mealy bugs. If a single house can 

 be closed off and the stock is wholly of one kind of 

 plants, as violets or chrysanthemums or carnations, it 

 is possible to so adjust the treatment that no injury will 

 befall the plants and the insects will be destroyed. 

 Prof. GEORGE C. BUTZ, Horticulturist Pennsylvania 

 Agricultural Experiment Station. 



Rhode Island. I believe that the gas treatment for 

 the destruction of insects upon nursery stock is the 

 only efficient method for the destruction of certain of 

 the pests, and personally were I to buy plants for a 

 large orchard, or for use in the orchards which I 

 already have planted which are now free from San Jos6 

 scale, I would most surely buy them from some 

 nursery which would fumigate trees before shipment. 

 I believe that as the efficiency of this method of treat- 

 ment is more fully understood and appreciated by 

 warehouse and flour-mill owners that this will become 



