Rather, practice good culture to boost overall tree health. Other common leaf-spot diseases are Septoria spp . The spots caused by these, however, are larger and more irregular compared to the small, circular spots caused by spot anthracnose. Both Septoria and Cercospora infections result in angular lesions, and they're observed later in the year than spot anthracnose. Again, unless the tree is really infested, I would just practice good culture and skip the sprays.
Dogwoods demand excellent drainage.
The trees like a fertile, acidic soil, morning sun or filtered sun and accept bright shade. Those that receive a lot of shade are more prone to fungal leaf spots. Too much sun and the leaves scorch. Keep up the watering during drought. Water deeply, as light watering encourages shallow roots, which makes the tree more vulnerable to stress.