INSECTICIDES, PREVENTIVES, AND MACHINERY. 



459 



For the nurseryman this is an easy proposition, because he builds 

 a house of suitable size, of proper material, and so arranged that 

 it will close tightly, excluding light and air and retaining the gas. 

 For the orchardist the matter is less simple. He must have a 

 cover to fit around or over his trees, and the moving of a large 

 box always requires considerable help or mechanical aid. If the 

 trees to be treated are large, there must be a tent of oiled canvas 

 of great size and weight, and a special derrick or other me- 

 chanical contrivance to move it. No two trees being quite equal 

 in size, the amount of chemicals must be calculated for each. 



Professor W. G. Johnson's book covers all these points, and 

 should be consulted by anyone intending to consider orchard fumi- 

 gation in the East. On the Pacific coast conditions are so much 

 different that either a community owns an outfit and has trained 

 men to operate it, or it becomes a commercial matter, and outfits 

 may be hired, the owner of the trees simply footing the bills. 



