Daylilies require very little care and are ideal for the gardener wanting low-maintenance flowers. However, as easy as they are to care for, daylilies do have a few problems that can result in damage or death to your plants. We wanted to take a closer look at the most significant issues with growing daylilies. The following information has been gathered from the official organization on daylilies; The American Hemerocallis Society.
The good news, daylilies have very few pests, of which may only cause minor damage. One of the most common daylily pests is spider mites. Although usually active in hot, dry weather, they can be somewhat controlled simply by hosing them off. If necessary, one can use a pesticide that does not contain Kelthane, as it is harmful to daylilies.
The bad news, daylilies have an aphid that is specific to the flower and unlike typical garden aphids, are not easily controlled with agents such as soaps. These pests are typically active in cool weather in temperate zones and during the winter months in the subtropics. When it comes to pesticides, they must be Kelthane free and at a minimum contain a mildly systemic action.
Another pest to the daylily is thrips. The best control method is using a Kelthane free pesticide that has either a long residual or systemic action and is applied early in the growing season. Snails and slugs are known to feed at night on young tissues of daylilies, causing torn edges and holes. During the day, slugs and snails hide in cool, damp places like in dead foliage, mulch, or under rocks and bricks. Control methods include sanitation and pesticides specific for snails and slugs. Cutworms, wasps, tarnished plant bugs, Japanese beetles, grasshoppers, cucumber beetles, and cicadas are also known to affect daylilies. Deer may even find the flower buds appetizing.
If you are having issues with your daylilies and it is not a result of pests it could be diseases damaging your flowers.
Although some diseases are simple for the home gardener to recognize, others are more difficult, including crown and root rot. These may even require a professional laboratory diagnosis. It is essential that a gardener be able to understand what is typical for daylilies and their growth as it is not uncommon for one to confuse “summer dormancy” for plant disease or death.
Several indications that your daylily could be suffering from crown or root rot include plant yellowing and collapsing, leaves are easily pulled out, soft tissue, or plant death. You may or may not notice a foul odor with these diseases. Possible visible indicators of a fungus include “mustard seeds” for southern blight (Sclerotium rolfsii) and “shoestrings” for Armillaria rot. If uncertain of the disease diagnostic laboratory testing could provide an exact diagnosis. In addition to a fungal cause, other factors that could result in crown, or root rot include bulb mites, nematodes, bacterial pathogens, gardening practices, weather, moisture and soil aeration. As with daylily rust, some cultivars could be more prone to crown or root rot. Although these diseases may occur in cooler climates, they are a worry in warmer ones. Remedies include adequate air circulation, soil aeration, and proper drainage. You must also avoid over or underwatering plants and over-fertilizing or amending with organic materials that are high-water retentive. Do not plant your flowers too deep or transplant them during high temperatures. If dividing plants, let wounds air-dry prior to re-planting. If rot problem is persistent, it is suggested to get a laboratory diagnosis for proper treatment.
Fungus is the cause of some diseases that affect daylilies including daylily rust. The fungus responsible for the rust is Puccinia hemerocallidis and will appear as orange-yellow powdered specks on leaves and scapes. When leaves are wiped with a white tissue orange-yellow spores can be seen. Even if the rust causes leaves to die back the plant itself should survive. A few cultivars are more vulnerable than others. Treatment includes providing sufficient planting distance, proper air circulation and keeping overhead watering to a minimum. Avoid inadequate potassium nourishment and excessive nitrogen. If necessary, appropriate fungicides can be used.
Another disease resulting from a fungus (Aureobasidum microstictum) is leaf streak. This disease can be recognized by yellowing streaks, brown spots and die-back of foliage without plant death. Appropriate fungicides may aid in the elimination of leaf streak.
Our last problem to discuss may not be a disease at all, and its exact cause is unknown, but we felt it was important to include it in this topic. According to AHS, spring sickness occurs in early spring with daylilies showing discolored, twisted, bent, or stunted foliage on some of the daylily’s fans. Recovery and normal blooms occurring that season are uncertain. There may be several contributing factors to this daylily issue including bulb mites and leaf streak fungus. However, cold damage following shoot emergence is not a reason.
For more information on daylilies visit the AHS website.