Has the tree been getting enough water? Here in Northern Virginia (also zone 7), I have had to water since we have had hardly any rain this summer and my dogwoods are always the first to show drought stress. The experts here may have better information for you! Cynthia

It is a very common dogwood reaction to heat. The leaves will resume a more normal apearance once temperatures cool down as we approach fall. Nothing to worry about :-) And trees that are well established in the landscape tend to outgrow this reaction. Bigger, better established root system = less stress from heat or drought