Maple tree dying
Many factors affect the health of trees. Diseases, insects, drought, extreme cold, soil conditions, construction activities, misapplication of herbicides, and many other factors affect the health of trees.
The branch dieback in the maple tree in the photograph could be due to Verticillium wilt. Verticillium wilt is a fungal disease that affects a wide range of trees and shrubs in Iowa. Information on Verticillium wilt can be found at the following website.
A plant specimen can be sent to the ISU Plant and Insect Diagnostic Clinic for a more definitive diagnosis. Tips for submitting plant specimens to the clinic can be found at http://www.ent.iastate.edu/pidc/