ability to withstand the many stresses placed on them, such as the struggle 

 for nutrients, water, and light. Old plants eventually die and this brings 

 about a regeneration of young plants that eventually fill the open spaces. 



Ravine maintenance never ends — it requires constant vigilence. 

 Financially, it is cheaper to maintain than repair. The homeowner should 

 continually watch for problems in ravines on his property, such as the 

 beginnings of active erosion, minor excavations, soil fill, and the dump- 

 ing of clippings, leaves, and other debris. Other problems to watch for 

 include insect pests, diseases, falling trees, and fire. 



Before disturbing a ravine in any way, the homeowner should seek 

 professional advice. This is particularly true when beginning some kind 

 of construction that could injure or kill large trees. Root systems are 

 severely injured during excavating operations, and many trees and shrubs 

 will not tolerate soil fill, which prevents adequate penetration of moisture 

 and air into the root zone. Remember that one mature tree is more helpful 

 in controlling erosion than a number of young ones. 



In the spring and early summer of 1977, a survey was made of the 

 trees in the Highland Park area for serious insect pests or diseases. Only 

 minor insect problems were observed at that time, none of which require 

 control measures. In some years, it is known that the fall cankerworm, a 

 defoliating insect, can be a problem. IVhen protection is warranted, such 

 as for some of the older, more prominent trees, this insect can be controlled 

 by spraying. Oak wilt was the only disease observed during the survey that 

 could be of importance in the ravines. This disease was evident in a few 

 scattered upland areas and along the ridges of some ravines. Oak wilt is 

 a vascular disease that primarily affects red oak, but occasionally white 

 and burr oaks are attacked. Infected red oaks will die in one growing 

 season, whereas white and burr oaks may have only a few branches die in one 



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