Hemerocallis · Perennial
Hemerocallis gall midge: Remove and burn affected flower scapes as soon as symptoms appear to prevent larvae from maturing.
Lily beetle: Hand-pick adults and larvae regularly or use a biological control agent like nematodes.
Powdery mildew: Improve airflow by thinning clumps and apply a fungicide if infection is severe.
Slugs and snails: Use physical barriers like copper tape or apply slug pellets sparingly around new growth.
Root rot: Ensure well-drained soil and avoid overwatering; lift and divide congested clumps in spring.