Photo and text used courtesy Clemson University
Cooperative Extension Service.

This disease usually begins on lower leaves and gradually spreads upward. Concentric rings (target-like) that develop in leaf and stem spots are characteristic. The fungus may live in soils for 1 or 2 years. In addition, it is spread on transplants and by wind-blown spores.

It may appear on fruit, mainly as firm, dark-colored decay at stem end. Some of the newer tomato varieties have a moderate degree of resistance.