These symptoms look like Elsinoe Leaf Spot, a very common but minor fungal disease that dogwoods often contract in wet years. No intervention is necessary, and this sapling's infection is not putting other dogwood trees in the area at risk (spores are pretty ubiquitous, windborne and splashed around in rain, so can spread over a wide area, which is how this plant likely contracted the infection). Individual plants can vary in their susceptibility based on genetic resistance to disease, but likely none are totally immune. Since the infection only causes aesthetic damage and doesn't threaten the life of the tree, use of a fungicide is not warranted, nor would one cure any existing symptoms. In years with drier weather, infection will probably be reduced.

Miri

Thank you for providing all this information regarding our dogwood tree! I will be leaving it alone. Carol 
Sent from my iPhone



You're welcome!