Q.Browning pink dogwood tree
The tree looked great until planted. The hole was larger than the root ball, soil amendments added, the sod placed around the tree. Most of our soil is clay. The sprinklers are on every morning for 8 mins to help establish the sod. The soil around the tree appears to stay moist throughout the day. The flowers have browned and the leaves are browning, beginning at the tips and moving down the sides. Could it be getting too much water? Should I cut back on the watering and/or cut out the side to the edge of the canopy?
It looks like your dogwood has botrytis blight. Here is an article that will give you more information on botrytis blight and a course of treatment. You will need to keep the foliage as dry as possible so I would refrain from using the sprinkler for the time being.