58 DISEASES OF CULTIVATED PLANTS 



mist-like spray is obtained with a pressure of TOO pounds 

 than with a pressure of 70 pounds when the same apparatus 

 is used. The 'power' sprayers used in the United States 

 enable a much greater pressure to be easily and uniformly 

 maintained than is possible with the hand machines mostly 

 used in this country. In the United States spraying 

 machinery has undoubtedly received most attention, and has 

 reached the highest stage of perfection ; steam, gasoline 

 engines, and compressed air are used for the purpose of 

 wholesale work over large areas of fruit orchards, etc. ; by 

 such means it is possible to spray the tops of the highest 

 trees. (2) The deposition of a fine mist-like spray depends 

 also very much on the kind of nozzle used. The worst type 

 is where the water escapes as a solid rod-like stream, the 

 spray being formed by the action of the air on the stream. 

 Such nozzles convey the stream for a long distance, and are 

 used when spraying high trees, but the stream is not broken 

 up into fine spray however much force may be used, and a 

 considerable proportion of the solution trickles off the leaves 

 and does no good whatever. It is far more economical and 

 effective to use a nozzle of the 'Cyclone' or 'Vermorel' type, 

 in which a rotary motion is given to the liquid in a chamber 

 just behind the outlet, and in consequence of which the 

 stream emerges in a conical, fine spray. Such spray can be 

 made to reach the top of a tree by means of extension pipes, 

 or by rods. 



Where Bordeaux mixture is used, some automatic arrange- 

 ment should be present in the machine to keep the solution 

 uniformly mixed, otherwise one portion will be too 

 diluted to effect the desired object, and another portion so 

 concentrated as to injure the foliage. 



It proves most economical in the end to have all the pump 

 fittings made of hard brass formed of copper and tin. Soft 

 brass made of copper and zinc should be avoided, as it soon 

 wears out and is corroded by ammonia, etc. 



When fruit begins to ripen, spraying operations with 

 Bordeaux mixture should cease, otherwise the fruit is liable 

 to become spotted and consequently rendered unsaleable. 



Lodeman, The Spraying of Plants. Macmillan & Co. 



