Q: My dogwood tree has dozens of tiny purple spots on each leaf. The leaves are twisted and disfigured. Other dogwoods in the neighborhood look fine. How will this affect the tree?
A: Ah, sweet mysteries of nature! Why a disease affects some plants but not others is an enigma that puzzles all gardeners. The spots you describe are symptoms of a common dogwood disease: spot anthracnose (an-THRAK-nose).
If your tree is in good health generally, the disease will not hurt it too much. Heavily infected leaves will fall off in June but the tree will replace them with new foliage.
Spot anthracnose is worse some springs than others, due to weather variations. To guard against the problem next year, rake and destroy all leaves from the tree this fall. Next March, spray the tree at weekly intervals with chlorothalonil (Daconil) until late April.
This disease is not the one that has destroyed dogwoods throughout the Great Smoky mountains. That blight, Discula destructiva, seems not to affect landscape dogwoods to any great extent.