166 PRINCIPLES OF PLANT CULTURE 



the top of the trees is necessary. These rods, known 

 as extension rods, are most frequently made of a bam- 

 boo pole with a small brass tube running through the 

 center. 



Nozzles are of various types, but one which breaks 

 the spray up into a fine mist is, as a rule, most desir- 

 able (Fig. 74). The cyclone or eddy-chamber type of 



Fig. 73. — Power sprayer for commercial orchard. 



nozzle, of which the Vermorel is a good example, seems to 

 be most efiicient in producing this character of spray. 

 The disk nozzle, constructed on much the same general 

 principle as the eddy-chamber type and made so as to set 

 at an angle with the extension rod, is the type most largely 

 used. The Bordeaux type of nozzle is used to some 

 extent for special purposes. 

 Many of the common spray materials are merely held 



