The watering needs of your trees differ from those of turf. Turf requires short but frequent watering, while trees need deep and infrequent soaks, emulating a deep soaking rain. This means you need separate watering systems/schedules for turf and trees.
Transition trees from turf irrigation to deep, infrequent watering. With time, the tree's roots will deepen, reducing stress on the tree as watering is reduced. The following timeline depicts the gradual root changes of a healthy tree.
Trees take many years to mature and dead trees are dangerous and expensive to remove. Standing dead trees are also a fire hazard. Turf, on the other hand, is quickly and inexpensively replaced with sod or seed. Remember that trees in all locations are expected to be watered, with the volumes and schedule that keep them healthy.