Colorado Blue Spruce Embraced Locally
By Jeff Burbrink
Extension Educator, Purdue Extension Elkhart County
GOSHEN — One of the trees people embrace locally is the Colorado Blue Spruce. Their blue or blue-green color, and pyramid shape makes them ideal for some variety in the landscape, as well as winter color.
As the name implies, Colorado Blue Spruce trees are not native to the area or our climate. Colorado is a part of the arid west, experiencing much less rainfall than the midwest, low humidity, and soils that are less fertile. Blue spruce send their roots down through the cracks and crevasses on the mountainsides, finding water and anchorage in the toughest of environments.
As the popularity of blue spruce has increased in the midwest, so have the reports of failed plantings. Being relocated to a region where the humidity is high, the soils are rich and deep, and rainfall is more plentiful has not been a friend these trees.
The key symptom of spruce decline is branch dieback, which progresses over four or five years and renders the plant’s appearance unacceptable for most homeowners. The rapid decline of spruce trees is due to an increase of canker diseases coupled with other disease and insect problems that plague the species. Once the spruce population reaches a “critical mass” in a region, it seems the trees decline can be seen on every tree.
There are three diseases that seem to work in tandem with each other: needlecast, tip blight, and canker diseases. Needlecast causes needles to drop from the interior of the plant, leaving an outer shell of newer needles on the branches. Tip blight attacks newer emerging shoots, and the canker diseases affects branches and cause wounds that ooze sticky resin that often turns white. https://bit.ly/3tuC2AM
If that is not enough, two insects have an appetite for blue spruce. Spider mites seem to attack the trees when they come under stress, particularly in drought conditions, and the gall adelgids malform tips of branches, creating a cone-like gall that turns a reddish-purple color. In most cases, it’s the diseases and not the insects that make the trees unattractive.
Some of the information online might give you hope that spraying may solve these issues, but those are often lacking some of the practical information that would lead you to a better decision. For instance, many sites tell you there are fungicides available for control of the diseases. What they often fail to mention is that fungicides do not cure diseases, they prevent diseases. A blue spruce riddled with the diseases mentioned above is not going to recover when sprayed if symptoms are visible to the average person.
Secondly, fungicides must be reapplied, frequently, as long as conditions favor the diseases (wet or humid). That might be every 14-28 days depending on the product. Wet and humid pretty much describes our Indiana summers to a T. Fungicides are very expensive, too, and reapplying them is not a good fit with most wallets.
Third, fungicides need to be applied to the entire tree, like a protective blanket. Spraying the bottom third of a tree is a waste of effort. Most people will need to hire that done; again, a hit to the wallet.
What is a person to do? First, do not plant more blue spruce. They should be sold with a tag that says guaranteed to get sick in a few years.
Second: enjoy them while you can, but realize there is a point you will no longer like the way they look. Make plans to replace them with something more tolerant of our midwestern conditions. https://bit.ly/3sR642F