Hemerocallis sp. (Daylily) Aureobasidium microstictum (leaf streak) causes reddish spots with yellowish margins that often result in brown streaks down the center of the leaves. Usually this leaf disease does not cause the death of the plant. Fungicides and sanitation are helpful.
Daylilies are very cold hardy. However when these plants are emerging from the soil and are growing vigorously they are susceptible to frost injury. The frost injury often becomes infected with saprophitic fungi.
Written by James Schuster, Extension Educator, Horticulture, and reviewed by Bruce Paulsrud, Extension Specialist, Plant Pathology and Phil Nixon, Extension Entomologist, University of Illinois at Urbana-Champaign.