Colorado Blue Spruce (Picea pungens) is one of the most recognizable and widely planted conifers in Michigan landscape. Unfortunately, blue spruces have been encountering some seriously health-threatening problems in recent years. Most of the problems are from disease are killing branches and eventually the entire tree. Industry experts are calling this “Spruce Decline”. This epidemic has caused many to believe that the blue spruce will become extinct.
There are a variety of factors that may contribute to Spruce Decline. It is believed that there are two reasons for this problem. First, we have overplanted blue spruce, just as we do with most popular plants. Do you remember the Dutch Elm Disease and the very recent Emerald Ash Borer? Overplanting often leads to buildup disease and pests with so much food and survival potential for these causal factors. Second, we have taken a tree that is “native” to the slopes (well drained, perhaps even droughty, nutrient poor) of the Rocky Mountains to clayish, poorly drained soils of Michigan. Other species of spruce (Norway, white, black, Serbian, etc.) may contract some of these problems as well…even though they are generally not nearly as seriously affected as blue spruce. Here at Thoms Bros. we are not recommending to plant Colorado Spruce, but use Norway and other Spruces more than not.
The biggest problem of this “Decline” are the Canker Diseases. Caused by fungi, the most common are Phomopsis, Cytospora and Diplodia. But other issues include Needlecast Disease, Pitch Mass Borer, Cooley Spruce Gall and Cultural/Environmental Problems.
Managing these issues is very complex. The biggest solution is to not overplant and when planting to allow adequate spacing to allow air movement. Using several varieties of spruce , pine, and fir on a jobsite would protect you from a larger problem. Pesticides can definitely be used to control the disease and pest problems, but the key to solution is recognizing the problem early enough. Many clients come to us after the plants have declined to much and are beyond salvageable. If you have Blue Spruces on your property, have our Arborculturist (from our key partner, GreenTrees) put you on a program.