The attached tree appears to have an infection. Can you look at it and do a...
The mulch around the tree looks excessive. This can reduce soil oxygen for the roots. When mulch is piled up against the trunk the bark decays and may cause decline. Also, the tree may have been planted too deep or the tree may have been planted high. We cannot say from the photo. You should be able to see the flare at the base of the trunk where it joins the root system.
At this point remove the excessive mulch and make sure it is no thicker than several inches and keep away from the trunk. Pull back the bark and look for any weeping, decayed, or wet spots. Remove any bark that is jagged or hanging. You may be able to see a ridge (a new layer of bark that forms) that it is trying to heal itself. A healthy tree may be able to isolate the wound and go on living. There are no chemical controls recommended. Keep the tree watered during dry periods next season and monitor the health of the tree.
See our website for more information on excessive mulch http://extension.umd.edu/hgic/excessive-mulch and planting too deeply http://extension.umd.edu/node/6235