When were they planted?

What has your weather been like the past few weeks?

Stick your finger around the base of the tree. Is it powdery dry? Soggy? Mushrooms growing?

When you planted these trees in your clay soil in holes to which planting mix was provided, it is like planting in a bowl, which may or may not drain. The roots will have no incentive to grow into a compacted clay, and out of the planting mix. As hoovb indicated the roots may soggy wet or powder dry, you will need to find out. It is better when planting a tree to water clay soil a day or two ahead to facilitate digging an area at least 16 square feet to condition the soil for planting. Plant the tree at the same depth or an inch or two higher than when in the container, in the native soil. Mulch with a couple of inches of compost and water it in. If your trees were recently planted you may decide to replant. Al