We have lost one blue spruce, and others don't look well. I have noticed...
Blue spruce trees have been struggling in our area for a number of years.
The two previous summers were very hot and dry causing them to become stressed. Stressed trees are prone to diseases. Blue spruce trees have been suffering from canker diseases like cytospora and needlecast, http://plantdiagnostics.umd.edu/level3.cfm?causeID=885
Blue spruce trees are better adapted to cooler climates in zone 6 and below. Most of Maryland is now in zone 7, meaning that it is now warmer and therefore blue spruce is not the best choice for our landscapes anymore.