Greetings from the garden bed. We daylilies (*Hemerocallis*) are generally tough plants, beloved for our vibrant blooms and resilience. However, even we face challenges from tiny invaders and silent sicknesses. To help you keep us thriving, here is a detailed account of the problems we commonly encounter, told from our perspective.
Our sturdy leaves and flower buds are full of delicious sap, which attracts several unwelcome guests. The most common are aphids. These tiny, soft-bodied insects cluster on our new growth and buds, piercing our tissues and sucking out our vital fluids. This causes our leaves to curl and distort, and a sticky residue they leave behind, called honeydew, often leads to a black, sooty mold that blocks sunlight. Similarly, spider mites are minuscule arachnids that thrive in hot, dry conditions. They feed on the undersides of our leaves, causing a characteristic stippling of yellow dots. A severe infestation leaves us looking dusty, pale, and covered in fine webbing, severely weakening our ability to photosynthesize.
Another significant pest is the thrips. These slender insects are particularly frustrating as they rasp the surface of our developing flower buds and then suck the oozing sap. This feeding results in buds that may fail to open, or if they do, the petals are streaked, discolored, and distorted. You might see brownish streaks or a "glazed" appearance on the petals, which ruins our most spectacular display.
Moist conditions, whether from rain, overhead watering, or high humidity, can lead to fungal issues that disfigure our foliage. The most widespread is **Daylily Leaf Streak**, caused by the fungus *Aureobasidium microstictum*. It begins as small, water-soaked spots on our leaves that elongate into brown or yellow streaks with reddish-brown margins. While it rarely kills us, it makes us look unsightly and can weaken us over time if the foliage is severely affected.
Another common problem is **Leaf Spot**, which can be caused by several fungi. These manifest as distinct, brown or tan spots with yellow halos on our leaves. In severe cases, the spots can coalesce, causing large portions of our foliage to die back prematurely. **Rust** is another fungal disease, identifiable by the raised, powdery, orange or yellowish pustules that appear on the undersides of our leaves. These fungi overwinter on our dead foliage, waiting for spring to start a new cycle of infection.
This is perhaps the most serious threat we face. While we appreciate consistent moisture, we absolutely despise sitting in waterlogged, poorly drained soil. This environment invites soil-borne fungi like *Fusarium* and *Sclerotium rolfsii* (Southern Blight). These pathogens attack our crown—the crucial point where our leaves meet the roots—and our root system. The first sign you might notice is a general yellowing or wilting of our leaves, even when the soil is moist. Upon closer inspection, the crown tissue will be soft, mushy, and brown or black instead of firm and white. Unfortunately, by the time symptoms are visible above ground, the damage below is often extensive and frequently fatal.
You can help us immensely with good cultural practices. Please ensure we are planted in well-draining soil and in a location with adequate air circulation. Water us at the base in the morning so our foliage has time to dry before evening. Most importantly, practice excellent garden hygiene. Remove and destroy any of our leaves that show signs of disease or insect damage. In the fall, clear away all of our dead foliage to eliminate overwintering sites for pests and fungal spores. Dividing us when our clumps become too crowded also improves air flow around our crowns, reducing the risk of rot. A healthy, well-cared-for daylily is naturally more resistant to these common problems.
