We have a Blue Spruce that we planted about 15 years ago. It is about 25 feet high and was doing well until last year. It sits at the end of our back yard, right in the middle of the yard. The top half of the tree is fine. But, as we face the tree from the house, the left side is fine but the bottom half of the right side is 'thinning ' quickly and there are a lot of bare spots. We have watered and fertilized the tree, but it has not seemed to help. We get the afternoon sun in the back yard. Any suggestions??
Colorado blue spruces are ultimately not happy growing in Maryland climate and are susceptible to two needle cast diseases, both fungal: cytospora and rhyzospheria. They have very similar symptoms, beginning with thinning, browning and dieback at the bottom of the tree. There is very little that can be done. Here is info from our website: http://extension.umd.edu/hgic/cytospora-canker-spruce