THE TREATMENT OF INSECTS AND FUNGI IN THE UNITED STATES. 1Q9 



give here. The tent is usually of an octangular shape, and is 

 furnished with rings for hoisting. The largest tents require a 

 derrick for lifting them into place. The following are the 

 amounts of cyanide of potash to be used for trees of varying 

 heights : — 



Height of Tree. 



Amount of cyanide of potash 



| ounce . 



1 » • 



2 ounces. 

 4 „ . 

 8 „ . 

 1 pound . 



If as broad as high (Navel 

 oranges, &c.) 



If § as broad as high (Seed- 

 ling oranges, &c.) 



8 feet 

 10 „ 

 12 „ 

 15 „ 

 20 „ 

 28 „ 



Sprays or Washes. 



The most important remedies for plant pests are applied as a 

 spray or wash. By the word "wash" one would naturally understand 

 a more copious application than a spray, but in ordinary usage 

 the terms are identical. For very low plants an outfit working 

 on the principle of a sprinkling -can will do ; but for better and 

 more economical work, and work on higher plants, some form of 

 force pump and spray nozzle is necessary. There are many 

 forms of pnmps on the market that are good for the purpose. A 

 spray pump should maintain a fairly constant and sufficient 

 pressure, and its valves and general construction should be 

 simple and its parts easily replaceable. The nozzle should, for 

 most spraying work, be such as to break up the stream into a 

 fine mist ; but for scale insects one giving a stream of con- 

 siderable force is desirable. The shape of the spray is usually 

 either conical or fan-shaped, and each has its particular advan- 

 tage for a particular class of work. The construction of the 

 nozzle should be such as to permit of easy, quick, and thorough 

 cleaning. A few forms, designed to clean themselves automati- 

 cally, work well. In most spraying the object is to get the 

 largest possible proportion of the spray to remain on the leaf or 

 stem, and to have it well distributed. This is best accomplished 

 by covering the leaf with minute globules like dew. As soon as 

 they run together and drip from the leaf the distribution is not 



