1911.] PUBLIC DOCUMENT — No. 31. 49 



ligure anj'thing it touches, Tlio writer has been of the opinion, 

 however, for some time, that the high-pressure, large-nozzle 

 equipments are the cheapest and most practical for shade-tree 

 work. 



What might be termed a compromise between the fine-nozzle 

 system and the high-pressure, coarse-nozzle 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 aperture of %2 of an inch, When used on a hand 

 ])ump with a pressure of from 50 to 70 pounds, or even more, 

 it does not give, in our estinuition, a satisfactory spray. Where 

 a small nund)er of trees are to be sprayed, and where 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 most important factors 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 competent men to do the work. By high pressure 

 we mean a pressure of 200 to 250 pounds, preferably the latter. 

 This should be maintained constantly, and the capacity should 

 be sufficient to maintain this pressure in a 1-inch delivery hose, 

 if necessary. 



In our work on spraying shade trees we endeavor to have a 

 1-inch aperture from the pump to the nozzle, care being taken to 

 have no reducing valves or couplings anywhere on the line to 

 reduce the volume of the spray, since it is better to have a good 

 flow of the spraying mixture directly to the nozzle. 



Too much attention cannot be given to the nozzle. It should 

 be adapted to the work required of it, and a satisfactory nozzle 

 is worth almost any price. It should be constructed on mechan- 

 ical principles which will enable it to break up the s^^raying 

 mixture into as fine a mist as possible, and to do this at a dis- 

 tance convenient for the economical application of the spray. 

 The ideal nozzle for the economical spraying of trees either 

 from the ground or a ladder should possess some carrying fea- 



