City Forester Brian Jorgenson said the disease is a fungus that attacks leaves and growing tips of American sycamores. The fungus kills the leaves and defoliates the tree. The leaves curl up or appear limp and may blacken slightly.

He recommends that landscape professionals continue watering affected trees—even after they have defoliated—so the tree remains healthy and can push new leaves.

“This disease will not kill the trees,?EUR??,,????'?? Jorgenson said. ?EUR??,,????'??The trees will use their energy reserves to set new buds and push new leaves this summer.?EUR??,,????'?? Treatments, though, won’t help infected trees this year.