252 MASS. EXPERIMENT STATION BULLETIN 170. 



pump with a pressure of from 50 to 70 pounds, or even more, it does not 

 give, in our estimation, a satisfactory spray because it is not broken up 

 sufficiently. When a small number of trees is to be sprayed and an expen- 

 sive equipment cannot be afforded, small hand pumps will do the work, 

 but when it becomes necessary to spray 500 or 1,000 trees in the course 

 of a few weeks, power sprayers are necessary and more economical. 



The Bordeaux nozzle has the advantage of being adjustable and can 

 be used either as a mist nozzle or at more or less long distance. As a 



long-distance nozzle, how- 

 ever, under any pressure, it 

 is unsatisfactory and much 

 inferior to other long-dis- 

 tance sprays. Moreover, 

 with the use of the Bordeaux 

 nozzle it becomes necessary 

 to use a ladder and to do 

 some climbing. The aperture 

 is so small that with any 

 pressure the stream is limited 

 in its height. 



The most important fac- 

 tors necessary for economical 

 work in spraying shade trees 

 on a large scale are machines 

 powerful enough to maintain 

 a constantly high pressure, 

 an efficient nozzle, and com- 

 petent men to do the work. 

 By high pressure we mean a 

 pressure of 200 to 250 pounds, 

 preferably the latter. This 

 should be maintained con- 

 stantly, and the capacity 

 should be sufficient to mam- 

 tain this pressure in a 1-inch 

 delivery hose, if necessary, provided with a nozzle with an aperture one- 

 quarter inch or more in size. With the mist nozzles, or even with the 

 Bordeaux nozzle, a pressure of over 150 pounds is useless and unneces- 

 sary. With this pressure, or even less, depending on the nature of the 

 nozzle employed, the maximum results may be obtained. It is extremely 

 important for the best work in spraying that there should be as little 

 friction as possible. Therefore, care should be exercised to have no reduc- 

 ing valves or couplings anywhere on the line to reduce the volume, since 

 it is essential to have an uninterrupted flow of the spraying mixture 

 directly to the nozzle. In this respect the fixtures usually found on the 

 market are poorly adapted to good work, and are often useless, with the 



FIG. 108. "M A. C." nozzle spray with high- 

 pressure and atomizing point intercepting the 

 stream. 



