Insect Damage 53 



involve the water-supply, the supply of oxygen, and the 

 supply of nutritive elements. 



The most common symptom of unfavorable soil condi- 

 tions is found in the paling or etiolation of the leaves, which 

 become prematurely yellow, wilting and falling before the 

 end of the season; while in other cases the leaves and buds 

 are reduced in size. Branch-tips, especially of horizontal 

 branches, are killed back, and the top of the crown dries 

 and dies, giving rise to the so-called staghead; or else water- 

 sprouts, slender, long, wisp-like shoots out of the regular 

 order, are formed. Excessive growth of moss and lichen 

 may also be an accompanying symptom. 



If the tree has been vigorous before, and has only recently 

 shown signs of weakness, we must note especially any 

 changes lately made in the soil conditions, which may 

 account for change in its vigor; such as the cutting down 

 or filling up of ground, making ditches, laying gas-pipes, 

 draining or flooding, cultivating or sodding, performances 

 which are apt to interfere with the root system, altering its 

 environment, and hence the amount of active root growth. 



If none of these investigations give a clue, we must then 

 inquire into the weather conditions and the history of the 

 preceding two, three, or four seasons, as well as into sur- 

 roundings generally, and we must ascertain what has been 

 the previous treatment of the patient. 



Thus circumspect investigation and observation and 

 historical evidence m.ust be brought together to diagnose 

 the more complicated cases, while in other cases the initiated 

 may be able at once to determine the cause of the abnormal 

 condition. The novice will have to examine with more care, 

 especially to avoid the mistake of recognizing as the pri- 

 mary cause what is only secondary. 



Insect Damage. The most obvious damage is that done 



