KALAMAZOO, Mich. — Colorado blue spruce trees have long been one of the more popular conifers for landscaping across the upper Midwest. Now, diseases are killing blue spruce trees across West Michigan and trees are declining at a rapid rate. Members of the pine family, the trees are efficient growers and have a beautiful blueish foliage. According to the Michigan State University Extension, the key symptom of spruce decline is branch dieback, which usually starts with a browning of the lower branches then progresses up the tree over the course of two to four years. Darren Williams manages 4 Seasons Tree Service, based in Kalamazoo. He estimated his crews have taken out over 500 blue spruce trees in recent years due to fungal diseases known as needlecasts.