CLS symptoms include circular leaf spots scattered on the leaves near the base of the plant. The center of these spots on bigleaf hydrangea turns tan or light gray and surrounded by a purple halo. The disease is mostly an issue in the landscape than in greenhouse production.

The center of these spots on bigleaf hydrangea turns tan or light gray and surrounded by a purple halo. Premature leaf drop can lead to loss of plant vigor and setting of the flower bud.

The underside of the big leaf hydrangea leaves have a frogeye pattern. These spots however tends to be angular in oakleaf hydrangea.

Fallen diseased leaves serve as the primary source of spores of the pathogen. The spores are spread to healthy leaves by splashing water. Frequent summer rains are conducive for disease spread.