164 HATCH EXPERIMENT STATION. [Jan. 



by either insect or fungi, although at times there may be 

 observed a few aphids on them, which it is generally sup- 

 posed are the cause of the trouble. The causes of these 

 troubles, however, are in many instances to be traced to 

 conditions which are peculiar to our times. In this age of 

 electric lights, trolley cars, sewers, pavements, gas, and 

 transmission of steam for heating purposes, it must be 

 confessed that the practice of setting out shade trees along 

 the borders of streets in our cities becomes rather discour- 

 aging. The price of enjoying these modern appliances of 

 scientific thought means more than the mere cost of digging 

 up our city streets and lopping off the limbs of trees every 

 few months ; in many instances it means the death of many 

 shade trees, and it may eventually lead to the question 

 whether it is worth while to bother at all with trees for our 

 city streets. The sickly, disfigured, mutilated specimens 

 of trees which are now and then seen in our busy city streets 

 have very little to recommend them, and in many cases 

 thoroughfares would become improved without them. 



Some of the agencies which more especially affect our 

 trees are electricity, gas and steam. These may affect the 

 tree directly, by escaping and coining in contact with some 

 portion of it, or indirectly as by the lopping of limbs for 

 wires or the digging of trenches for the pipes, which very 

 frequently results in destroying portions of the root system. 

 There are other agencies, however, which are associated with 

 the death of the tree. One of these is the borer that is very 

 troublesome to the rock maple. Trees affected with these 

 can be readily detected by an examination of the bark of the 

 tree for round holes about one-quarter of an inch in diameter, 

 and in autumn the affected limbs can be readily detected by 

 a premature coloration, or hectic flush, as it were, of the 

 leaves. Then, again, there is the work of horses' teeth, 

 which, according to Mr. James Draper, who has had many 

 years' experience as a park commissioner at Worcester, in- 

 flicts more damage than any other single thing to city trees. 

 Many of the specimens of diseased shade trees which are 

 sent in to us year after year can be referred to one of the 

 above agencies as a cause of the trouble. 



