From our perspective as daylilies (*Hemerocallis* spp.), we are generally resilient plants, but our vibrant blooms and lush foliage can be compromised by a variety of pests and diseases. Understanding these issues from our point of view is key to maintaining our health and beauty.
Our tender new growth and flower buds are particularly susceptible to aphids. These small, soft-bodied insects cluster on our undersides, piercing our tissues to feed on our sap. This draining weakens us, causing our leaves to curl and distort, and can lead to the development of sooty mold on the sticky honeydew they excrete. Similarly, spider mites, which are nearly microscopic, thrive in hot, dusty conditions. They feed on our individual cells, creating a stippled, yellowish pattern on our leaves. A severe infestation leaves us looking bronzed, dehydrated, and covered in fine webbing, severely impacting our ability to photosynthesize.
Daylily rust, caused by the fungus *Puccinia hemerocallidis*, is a significant concern. It appears as small, raised yellow-orange pustules on our undersides, often with corresponding yellow spots on the upper leaf surfaces. This fungal infection saps our energy, leading to premature yellowing and die-back of our foliage, which weakens our root systems for the following season. Leaf streak, caused by the fungus *Aureobasidium microstictum*, manifests as long, brown streaks along the central vein of our leaves, often starting at the tip. While rarely fatal, it mars our appearance and can reduce our overall vigor if left unchecked.
Perhaps the most dangerous problems we face occur at our crown and roots. Crown rot and root rot, often caused by fungal organisms like *Sclerotium rolfsii* or bacterial soft rot, are frequently a result of poor drainage or overwatering. From our perspective, sitting in saturated soil is a death sentence. Our roots suffocate and rot, unable to take up water or nutrients. This decay spreads to our crown—the crucial point where our leaves meet our roots—causing the leaves to yellow, wilt, and pull away easily. This condition can rapidly destroy an entire clump of us.
These microscopic roundworms are stealthy attackers. Root-knot nematodes (*Meloidogyne* spp.) infect our root system, causing the formation of galls or knots that disrupt our ability to uptake water and nutrients. Above ground, we appear stunted and nutrient-deficient. Foliar nematodes (*Aphelenchoides* spp.), however, move up from the soil in water films and enter our leaves through stomata. They feed inside our leaves, creating distinctive yellow-to-brown lesions between the veins, which eventually turn black and can cause large sections of our foliage to die back.
