Informational table showing disease name, symptoms, pathogen/cause, and management of Hemerocallis (Daylily) diseases. Disease Symptoms Pathogen/Cause Management Colletotrichum leaf spot or leaf scorch Leaf tissue dies in a streak along the mid-vein. Colletotrichum dematium Remove infected leaves. Destroy leaf debris at the end of the season. Avoid overhead irrigation. Leaf streak or Red leaf streak Reddish fleck form on the leaves as the mid-vein yellows. Oval dead spots form and the leaves die prematurely. During wet conditions wet, shiny masses of white spores can be seen with a hand lens on the brown leaves. Aureobasidium microstictum Remove infected leaves. Destroy leaf debris at the end of the season. Avoid overhead irrigation. Cultivars vary greatly in susceptibility. Apply a fungicide to protect plants. Rhizoctonia crown rot Slender, grassy foliage develops and few flower stalks form. Crowns rot and die. Rhizoctonia, usually following freeze injury. Protect crowns from freezing. Russet spot Reddish spots form on the leaves. Unknown.
Rust Bright yellow spots or streaks on the upper side of the leaf have bright yellow-orange spores on the underside.. Puccinia hemerocallidis This fungus also occurs on Patrinia spp. (and possibly Hosta, but this has not been observed in the U. S.). Most cultivars are susceptible. Remove infected leaves and immediately place them in a plastic bag for disposal. Keep the bag closed. Apply a fungicide to protect plants.