Thank you for contacting AaE for help.

It looks like you have a Colorado blue spruce. These trees are not suited to the climate here in Minnesota and as a result are susceptible to a couple of different diseases; one of which looks like what I'm seeing in the picture, Rhizosphaera needle cast.

Several other fungi result in a similar look so it is best to send in a sample to the U of MN Extension Plant Disease Clinic for a confirmation before making a decision on what to do. Here is a link to the clinic's website which lists its services and prices and how to submit a sample.

Here is a link to more information about Rhizosphaera needle cast from the U of MN Extension.

As for the other trees in your backyard.  If they're younger Colorado blue spruces, they may not have had time to develop the symptoms of the disease. Or maybe they are of a less susceptible species of evergreen.

Best of luck!