Based on the photos it is not possible to make an accurate diagnosis. The following is a description of the three most common diseases affecting spruce in Michigan. Possibly by studying this information and carefully examining your trees you can make a diagnosis.

Cytospora Canker: This disease does not kill the plant outright, but it does kill branches, usually near the base of the tree first. As the disease progresses, death moves up the tree. You will usually see a bluish-white resin on the trunk or possibly the branches. There are no effective chemical  controls for this disease. It is important to prune out and destroy branches with cankers. It is also important to keep the tree as healthy as possible by watering during dry periods. The following site has excellent photos that will help you to identify this disease. It also explains in more detail the steps that can be taken to control the disease.

http://www.pestid.msu.edu/LinkClick.aspx?link=Factsheets%2fCytospora.pdf&tabid=218&mid=834

Rhizosphaera Needle Cast:  This disease tends to infect older (inner) needles first. The needles turn brown or purple and drop from the tree. If you have a good hand lens you can see the fruiting bodies on the needles.  You can prevent new growth from infection by spraying with Chlorothalonil. Daconil 2787 is one brand. The application should be done when the new shoots are ½ to 1-1/2 inches long and again in 3 to 4 weeks when the shoots have fully expanded. Additional applications at 3 to 4 week intervals may be necessary. The following website gives more details and excellent photos.

http://www.pestid.msu.edu/LinkClick.aspx?link=Factsheets%2FRhizosphaeraCS3.pdf&tabid=218&mid=834

Phomopsis : The initial symptoms are very subtle, just a slight discoloration of the needles. Eventually needles may turn brown or purple and drop. In the spring new shoots will expand and then rapidly wilt and die. Cultural control includes removing lower branches that are infected. These branches can be identified by the dead terminal buds. Also keeping the plant well watered during periods of drought is important. Benzamidole fungicides such as Cleary’s 3336 should be applied at bud break and at 3 week intervals until new shoots are fully developed and hardened off. More information and photos can be found at this website.  


http://web2.msue.msu.edu/bulletins/Bulletin/PDF/E2417.pdf

The following website also has some excellent photos of the most common spruce problems. http://files.dnr.state.mn.us/assistance/backyard/treecare/forest_health/whitesprucediagnosis.pdf

Spider mites insert their mouth parts into the needles and withdraw fluids, resulting in small yellowish spots on the needles.  In severe cases the needles may appear bronze in color and fall from the tree. The following website has some good photos of the damage from mites.

http://bugs.osu.edu/~bugdoc/Shetlar/factsheet/christmasstree/spruce_spider_mite.htm


If these trees are an important part of your landscape, I suggest that you have a certified arborist examine them. You can find a certified arborist at the following website. When at the homepage, click on “Find a Tree Care Service” and then enter your postal zip code. Some arborist will do an initial consultation at no charge.
http://www.treesaregood.com/  

I hope this information is helpful. If you have additional questions please reply back. Thank you for using our service.