Decline of Blue Colorado Spruce (Picea pungens glauca)

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The prevalence of diseases and insects on Blue Colorado Spruce trees has intensified in recent years and trees are declining rapidly in many areas. Many Blue Colorado Spruce trees in Ontario are in decline due to several factors that make them susceptible to insect and disease issues such as Cankers, Needlecast, Tip Blights, Pine Pitch Mass Borer, Spider Mites and Gall Adelgids. The key symptom of spruce decline is branch dieback, which progresses over 2-4 years and renders the plant’s appearance unacceptable for most homeowners.

This species of tree is not performing well in our environment and the decline has increased over the last 10 years in trees approximately 25-35 years old. The conditions that contribute to this decline, appears to start with poor growing and environmental conditions combined with new pathogens. Spruce trees are often planted too close and too deep. They do not like wet clay soils or compacted soils. These trees are not tolerant of drought conditions.

As with any tree health problem, the first step in dealing with declining Spruce trees is to diagnose the problem and identify the cause. In many cases there may be more than one issue affecting your tree’s health.

Most of these issues can be mitigated through good plant health care such as pruning, removals where necessary, fertilization, mulching, providing adequate water and reducing damaging pest populations if necessary. It is recommended to plant Blue Spruce trees on sites with full sunlight, good air movement and excellent soil drainage.
Aeration/Vertical Mulching /Mycorrhizae Inoculation using an air spade will help to improve soil porosity and structure by reducing soil compaction in the root zones of Spruce trees and provide an environment that encourages healthy root and shoot growth. This care is advised for young trees already planted into compacted soil.

Reference: Michigan State University Extension