Why is one blue spruce dying, and could it spread to others?

There are several pests that can cause needle browning and defoliation of blue spruce at this time of year. Spider mites and needlecast, a fungus disease, are two of the most common. Both pests are treatable, but neither are normally associated with death of the plant. I recommend contacting a certified arborist to evaluate the trees to determine the cause of the problem.