Asked April 10, 2015, 3:35 PM EDT
Washington County Minnesota
It is difficult to diagnose from the picture. A sample would be best for an accurate diagnosis (see below for more information on that). Cultural treatments include proper watering, pruning and cleanup and timely application of fungicides. Fungi need moist conditions, so keeping circulation around the tree and its branches can help reduce the spread. Avoid overhead watering of the branches as the wet conditions help the spread of the fungus. Prune out dead branches and sanitize the tools between each cut (one part bleach to nine parts water). Dip the cutters in the bleach mixture between each cut. Pruning should not be done when the foliage is wet. Try to remove infected material. The fungus can overwinter in the mulch and dead needles. You could use a shop vacuum to help clean up the dead needles. The following sites will help you diagnose the insect and disease pests on your trees. You will need to closely examine the needles. The following sites will help you.
You may want to hire the plant disease clinic to diagnose the problem.