Urban environments are extremely hostile places for shade trees to grow and survive because there are many interrelated variables that may cause urban shade tree stress.  Stress may be defined as any environmental pressure that causes a change in a tree’s physiology that predisposes the tree to invasion by secondary organisms (disease & insects) that it would otherwise resist.  

Some of these urban environmental stress agents include drought, construction damage, soil compaction, lawnmower & weed whip damage, de-icing salt, vandalism, and air pollution.

Shade trees that are exposed to one or more of these stress agents are much more vulnerable to disease and insect attacks.  In fact, many insect pests will only attack a tree that is under severe stress.  By planting drought tolerant and/or native species and following proper planting, mulching, watering, and pruning techniques, you will help ensure that your tree remains healthy and vigorous and more able to fight off disease and insects.     

Routinely monitor your trees throughout the growing season.  If you notice anything that looks out of the ordinary, contact an International Society of Arboriculture (ISA) - Certified Arborist for professional assistance.