Tree Care & Diseases

An effective tree maintenance program, including regular inspections and the necessary follow-up care of mulching, fertilizing, and pruning can detect problems and correct them before they become damaging or fatal.

Tree Inspection

Tree inspection is an evaluation tool to call attention to any change in the tree’s health before the problem becomes too serious. By providing regular inspections of mature trees at least once a year, you can prevent or reduce the severity of future disease, insect, and environmental problems.

A reduction in the extension of shoots such as buds or new leaves, is a fairly reliable cue that the tree’s health has recently changed. To evaluate this factor, compare the growth of the shoots over the past three years. Determine whether there is a reduction in the tree’s typical growth pattern.

Further signs of poor tree health are trunk decay, crown dieback, or both. These symptoms often indicate problems that began several years before. Loose bark or deformed growths, such as trunk conks (mushrooms), are common signs of stem decay.

Any abnormalities found during these inspections, including insect activity and spotted, deformed, discolored, or dead leaves and twigs, should be noted and watched closely.

Common Tree Diseases and Insects

There are a number of insect pests and diseases that contribute to health decline and death of trees and shrubs. Following is a list of those common to the area, as well as a link to further information and treatment.

  • Fireblight is a highly destructive disease of several members of the rose family.
  • Spider mites infect Colorado and white spruce trees.
  • Cankers are a common fungal disease of poplar trees, killing the outer wood and bark of stems and branches.
  • Forest tent caterpillar damage can range from a thinning of the crown to the complete defoliation of aspen, poplar and other trees and shrubs. 
  • Spruce gall adelgid are aphid-like insects that produce galls or abnormal outgrowths on spruce trees. 
  • Aphids can cause damage to all trees and shrubs by piercing the tender plant tissue and drawing large quantities of plant sap.
  • Yellowheaded spruce sawfly larvae feed on the new needles of Colorado and white spruce, leaving only short brown stubs.