88 SHADE TKEES. 



partly grown specimens succumbing more rapidly and easily 

 than more nearly mature forms. A single defoliation rarely 

 harms a deciduous tree very much; but successive defolia- 

 tions weaken and eventually kill. And always a healthy, 

 well fed tree is less attacked by insects than a sickly starved 

 example which gives up in despair at the least provocation 

 and invites attack bv its verv inabilitv to resist. 



SPRAYING. 



Among the first things that must be realized in planning 

 work to avoid insect injury to city trees, is that by no means 

 all kinds of trees are equally subject to such injury, nor is 

 Municipal tnere ail 7 one treatment that is equally effective 

 work. ngainst all insects. There may be one city with 



1,000 trees on which insect injury may be kept down by a 

 single man during the season; another with half that num- 

 ber may require a power sprayer and a gang to run it for a 

 month. 



At the beginning, find out what trees there are and their 

 condition. Then, with the assistance of the entomologist, 

 you are in position to determine what outfit is needed to carry 

 on the work. It is quite possible to get a cheap sprayer, 

 which is, at first, adequate when run to the limit; but no 

 piece of machinery does well for any consider- 

 mSshlne? * a ^ e P ei> iod when run to the limit, and a cheap 

 outfit is usually a small one. You can get a 

 barrel with a pump that will force a spray to the top of even 

 a large elm, and I have personally worked with such an out- 

 fit; but it was hard on the man at the pump, the tendency 

 was to lose pressure and too much time was lost in the fre- 

 quent tank fillings required. 



For municipalities with trees running into the thousands, 

 power sprayers are essential, but no municipality that needs 

 a sprayer at all, should get anything less than a 200-gallon 

 tank upon which a pump capable of furnishing 100 pounds 

 of pressure to two lines of hose should be mounted. The 



