Tree Diseases and Insect Pests

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.

Diseases

To learn more about the following tree disease problems, visit Colorado State University Cooperative Extension - Gardening Fact Sheets.  These fact sheets describe disease symptoms and prevention & management techniques.  You will also find a fact sheet on "Environmental Disorders of Woody Plants" that covers sunscald, drought, overwatering & frost injury.

Insects

INSECT ALERT: Ips Bark Beetles

Due to the recent historic drought, the City of Fort Collins and other Front Range communities (Greeley, Denver, Colorado Springs) are experiencing an Ips Bark Beetle epidemic.  Tree care professionals in these communities have reported that Ips attacks are occurring on large, well-established, drought-stressed Colorado blue spruce.  The Blue spruce Ips beetle (Ips hunteri) is not considered a problem in native forests, but is quickly becoming a pest in the urban environment.  

So far, 45 large, Ips-infested blue spruce trees had to be condemned by the City of Fort Collins. 

Ips is a common group of bark beetles that infests pine and spruce trees.  Ips beetles rarely attack healthy trees and most problems occur on newly transplanted pines or when plants are under severe stress.  Several generations of ips can occur in a season.  There are 11 species of ips beetles found in Colorado.

To learn more about the following insects, visit the Colorado State University Cooperative Extension - Insects Fact Sheets.

These fact sheets describe the insect & life cycle, signs & symptoms of attack, and management techniques.