The Colorado blue spruce is a tall, classic-looking tree that was deemed noble enough to serve as the state tree in its namesake state. Colorado blue spruces are known for the blue-tinged needles that stay on year-round, though new needles join every spring, and for the bushy base that sits close to the ground.
If you have a Colorado blue spruce in your yard or property, you want to put in the work to make sure the tree stays looking as beautifully bushy and healthy as possible. There are a couple of tree diseases that can strike this spruce but a tree care service can help minimize the damage.
Rhizosphaera Needle Cast
Colorado blue spruce trees are particularly susceptible to the fungal disease rhizosphaera needle cast. The disease mostly threatens newly growing needles and younger trees. Symptoms will start to appear in spring as new needles grow in with yellow or red specks or blotches. Later in the season, the specks will darken to a purple or brown color. Affected needles can then fall off the tree prematurely.
The needle cast usually starts at the needles on the lower half of the tree and then works its way up. The disease is largely a cosmetic issue since the disease won't feed on the bark or heartwood of the tree. But yearly recurrences of the disease can leave your Colorado blue spruce looking barren and scraggly.
You can minimize the spread of the disease through your tree by hiring a tree trimming service to remove all of the affected needles as soon as the problem appears. Minimize the risk of the disease returning by not working on or around the tree during wet weather before the growing season begins.
Another fungal disease that can attack the Colorado blue spruce is cytospora canker. The disease targets older trees particularly those with prior weather or growing-related damage such as broken or dead branches.
The main symptom of a canker tree disease is the rounded canker sore-esque welts that will open up in the bark near a point of weakness such as a limb injury. But earlier stages of the disease can include needles that grow in purple-tinged and no signs of canker sores. So it is important to call in a tree care service for testing if you see needle discoloration so that the disease doesn't' have the chance to progress to the level that canker sores start appearing.
The tree care service can trim away dead or damaged branches so the disease has no place to form the cankers. Purple needles can also be trimmed away to minimize spread risk. Your tree service can apply a fungicide to the tree if there is damage to the heartwood that could lead to the disease spreading there and potentially killing the tree.