As a kid growing up, we always looked forward to Christmas. Picking out a spruce tree, decorating it and then planting it in the front yard so we could continue the tradition inside and out for years to come. Who can resist the beauty a Blue Spruce has to offer? But lately this stately tree has been plagued with declining beauty and many have suffered in the landscape leaving a less than desirable emptiness on the lower branches with a “shell like effect. Needles begin by turning yellow, brown/purple and then before long the tree is naked. The decline of Blue Spruce is leaving a “whole” in the Midwest landscape. No other tree can bring the majestic heughs of blues, greens and greys as a backdrop for many landscapes. Although wildlife will nest in its needles, the tree is not used as forage through our harsh winters. Recently there are two diseases that have plagued the Blue Spruce decline- Rhizosphaera and Stigmina.
Rhizosphaera and Stigmina are both fungal pathogens that render trees unacceptable in two to four years of being infected. Both fungi will infect the new stem growth and will become visible the following years as those needles are shed and the fungus progresses to the current season’s shoots. These fungi cause all the old needles to shed and gives the tree a “shell affect” with only current growth being visible before the tree declines and dies.
So the big question, should Blue Spruces continued to be planted? It is a difficult question to answer. You will see spruce decline in large areas and the decline seems to be increasing. It is not a certainty that all trees will be affected by either Rhizosphaera or Stigmina, but these fungal diseases are easily spread by air and water movement.
What can you do to give the spruce the best chance for survival? You will need to improve the planting areas as much as possible. Blue Spruce are native to Colorado which doesn’t have the humid summers that we are inflicted with. A few ideas to keep your Blue Spruce healthy is correct spacing when planting, full sunlight, good air movement and exceptional soil drainage.
Finally, if you begin to see symptoms in your tree don’t wait, get samples to your pathology labs for diagnostics and proper treatment. In this blog we have only discussed two possible problems, but Blue Spruce can be plagued with secondary diseases as well as cankers and insect problems.
Information for this blog came from Michigan State University studies of Blue Spruce decline. https://www.canr.msu.edu/news/what_is_spruce_decline_and_what_should_you_do_about_it