SHADE TREES. 



251 



pumps, etc., together with the utilization of coarse nozzles, more efficient 

 methods came into vogue. Some years ago the Gypsy Moth Commission 

 abandoned these fine nozzles and close-range methods of spraying, and at 

 the present time use is made only of wide aperture nozzles and solid 

 streams, with large hose. Exceptionally high pressure is obtained from 

 powerful machine sprayers. With the larger area which has to be treated 

 at the present day the older method would prove prohibitory, not only 

 on account of the expense, but also because of the time involved. Virtu- 

 ally all the spraying with 

 these large modern ma- 

 chines is done from the 

 ground, doing away with 

 the necessity for ladders 

 and for climbing trees; 

 and by using one or more 

 lengths of hose large 

 areas may be treated 

 from one spot. This 

 method of spraying trees 

 is very effective and very 

 much cheaper, the aver- 

 age cost of spraying 

 woodlands being some- 

 thing like $6 or less per 

 acre. With this method 

 the spraying mixture is 

 delivered to the nozzle 

 through a large strong 

 hose 1 inch in diameter, 

 under a pressure of 200 

 to 275 pounds, the high 

 pressure breaking the 

 spray up into a fine mist. 

 The spray has consider- 

 able spread when broken 



up, which is a desirable feature in treating woodlands and country road- 

 sides, but on this account it is more or less objectionable for use on resi- 

 dential streets in cities and towns, as it is likely to disfigure anything it 

 touches. The high-pressure, solid-stream equipments are the cheapest', 

 and are more practical for shade tree work than anything that has as 

 yet been devised. 



What might be termed a compromise between the fine-nozzle system 

 and the high-pressure, coarse-nozzle or solid-stream system employed in 

 the gypsy moth work is often used in spraying shade trees at the present 

 day. This consists in the use of the Bordeaux nozzle, which has an aper- 

 ture of about three thirty-seconds of an inch. When used on a hand 



FIG. 107. Spraying from the ground with solid stream 

 and high pressure (Worthley nozzle). 



