Second, water the root zone thoroughly, once per week, during dry periods in the spring, summer and fall. Don't water more often, because over-watering is one of the fastest ways to kill a tree. If you wait until cankered branches have appeared, it's usually too late. Another recommendation, but not always a popular one, is to plant hardier tree species. Colorado blue spruce, as the name implies, are a long way from home in an Iowa landscape.
Many native species are much tougher and less trouble-prone.
And if you plant hardy species, you won't need a visit from Dr. Tree-vorkian.