Concentric line patterns form within the brown spots as leaves yellow and fall.
Infected stems become dark brown to black in color and die.
Under moist conditions, salmon to pink colored masses of fungal spores form on the surface of dead stems. Large patches of plants are killed. Inspect transplants carefully and discard infected material. Avoid planting in areas of heavy shade or areas where moisture will be retained on leaves for prolonged periods. In established beds, remove diseased plants and thin the bed.