80 



is applied with great force, the stream is broken up into a fine mist, 

 which, if well directed, is evenl}^ distributed over the foliage and fruit, 

 and upon dr^nng leaves a more or less uniform coat. If the nozzle is 

 held close to the foliage, the force causes it to spread well, but the 

 coating is not so uniform as that which is derived from the mist. In 

 spra^'ing one-half of a tree the mist drifts through the tree from the 

 side which is being sprayed, and in that way the tree is well covered, 

 having received practically two incomplete sprayings. If fruit is 

 allowed to grow in clusters it is necessary to apply the spray with 

 great force in order to secure good results, 



MATERIALS FOR SPRAYING. 



CONTACT INSECTICIDES. 



Contact insecticides are those which kill the insects by touching 

 them. Kerosene emulsion and solutions of whale-oil soap are the sub- 

 stances that have been most used for this purpose; but on account of 

 the expense, the necessity of frequent application, and the fact that 

 the insect can be more -easily and effectively reached in other stages by 

 other insecticides, these kinds of spraying solutions have been used 

 but little against the insect. 



AESENICAL SPRAYS. 



The arsenical sprays contain arsenic as their essential ingredient. 

 Other chemicals are mixed with the arsenic for the purpose of pre- 

 venting it from burning the foliage or are products incidental to the 

 numerous compounds of arsenic which were used for other purposes 

 than spraying. There are many spraying compounds of which arsenic 

 is the base on the market, but there are many others which the fruit 

 grower can make for himself by combining the necessary ingredients. 



Paris green is probably the best known of these arsenicals. It has 

 been used for many years with success, and is a definite chemical com- 

 pound of arsenic, copper, and acetic acid. The composition is usuall}'^ 

 quite uniform, but many instances have been found in which it was 

 adulterated or the percentage of soluble arsenic was dangerously high. 

 As indicated by its name, it is a substance green in color. It is a 

 rather coarse powder, which has the fault of settling rapidly in the 

 spraying tank. It is quite necessary to use lime with Paris green in 

 order to counteract the burning effects of the free arsenic. Paris 

 green is comparatively expensive; in the East it costs about 20 cents a 

 pound and in the West 25 cents. 



Paris green may be prepared for spraying as follows: 



Paris green pound. . 1 



Lime - pounds. . 1 to 2 



Water gallons. . 100 to 250 



