How to Get Rid of Aphids on Daylilies

In the home garden, diseases and bugs don’t usually pose a big problem for daylilies (Hemerocallis species), as long as good gardening practices are used. Because of the summer heat in South Carolina, daylilies should be planted in fall or spring. Daylilies prefer well-drained soil with adequate organic matter. Have the soil tested for the correct fertilizer analysis to use. Then apply a slow-release fertilizer in spring before they begin to bloom. Plant daylilies in a mostly sunny site. Planting daylilies too deeply will result in reduced flowering and plant decline. For more information on daylily culture, please see HGIC 1163, Daylily.

Leaf Streak: Daylily leaf streak is caused by the fungus Aureobasidium microstictum. Long yellow streaks along the mid-vein of the leaf are a sign of infection. Infected leaves turn brown or get spots with yellow edges. These symptoms usually develop from the leaf tip downward. The infected leaves may wither and die completely.

Prevention & Treatment: Infected daylilies should be isolated from healthy plants. Daylily leaf streak may be avoided by purchasing disease-free stock plants and propagating only from healthy specimens. Avoid overhead irrigation. In the fall, cut off any dead leaves around the base of the plants and throw away the clippings. The fungus will survive the winter on the dead leaves, and in the spring, it will make spores that will infect new leaves. The daylily varieties Betty Bennet, Edna Spalding, Ella Pettigrew, Globe Trotter, Nancy Hicks, Pink Superior, Ron Rousseau, Sudie, Tropical Tones, Upper Room, and Winsome Lady are all resistant to these problems.

Fungicides like thiophanate-methyl or myclobutanil can be used to stop leaf streak. These chemicals slow the spread of disease and protect new growth that is easily infected. Begin sprays as new growth appears. Make 3 or 4 applications at 2-week intervals. See Table 1 for examples of products.

Daylily Rust: Daylily rust is caused by the fungal pathogen Puccinia hemerocallidis. The signs are like those of daylily leaf streak: the leaves have yellow to brown lines and lots of small yellow spots.

But one thing that makes daylily rust different is the development of small orange bumps on the underside of the leaves. These pustules produce the yellowish-orange urediniospores that spread to infect additional daylily foliage. These spores can be wind-blown or disseminated by gardeners handling infected plants. Daylily rust is capable of spreading quickly.

Prevention & Treatment: Inspect and purchase disease-free plants, especially the lower leaf surfaces. If you wipe rust-infected leaves with a white tissue, the spores will come off and leave a yellowish-orange stain.

Check for and plant resistant cultivars. Avoid overhead irrigation. In the fall, remove dead foliage from around the base of daylily plants and dispose of the clippings.

To aid in the control of daylily rust, plants may be sprayed with propiconazole, myclobutanil, or chlorothalonil. Spray at 2-week intervals as needed, and additionally spray after cutting back plants. Do not spray chlorothalonil during the blooming period. See Table 1 for examples of brands and products.

Root-Knot Nematode: Root-knot nematodes (Meloidogyne species) can cause loss of vigor and severe decline of daylilies. Infected plants slowly deteriorate, grow poorly, become stunted, turn yellow, wilt, and often die. The symptoms are very similar to moisture stress. Roots will often have small bumps or nodules where the nematodes feed and inject toxins.

Nematodes are most common in sandy, moist soils. They are generally more of a problem on former cropland that has been re-utilized for residential use.

Staying safe Because the root-knot nematode clearly galls plant roots, whole plant samples should be sent for testing instead of soil samples like for other soil nematodes.

The best option is to choose plants that are not susceptible to the root-knot nematode. Remove and dispose of infested plants, but do not add them to the compost pile. See HGIC 2216, Root-Knot Nematodes in the Vegetable Garden, for more information on how to get rid of root-knot nematodes and how to tell if they have done damage.

Soft Rot: Pectobacterium carotovorum causes bacterial rot at the base of daylily flowers and in their rhizomes. This bacterium that causes soft rot is a common soil inhabitant. High temperatures, poor air circulation, poor soil drainage, and improper fertilization all favor soft rot disease development. The crown (or base) of daylily plants with soft rot may have a strong, disagreeable odor.

Insects & Other Pests

Flower Thrips (Frankliniella tritici): Flower thrips and various other thrips species are serious pests of daylilies. Thrips are slender, dark-colored insects with fringed wings. Adults are less than 1/16-inch in length. To see these small, fast-moving pests, use a 10x magnifying lens. Thrips are typically found on leaves and between flower petals. To get food, both adults and nymphs (young insects that look like adults but are smaller) scrape the surface of plant cells to get to the sap inside. When they feed on flower buds, the flower may die without opening. With a light infestation, their feeding causes leaves to have silvery speckles or streaks. With severe infestations, leaves and flowers are stunted and distorted and may turn brown and die.

Sampling: As a result of their small size, thrips are difficult to detect before damage is obvious. Put some leaves and flowers under a piece of stiff white paper to look for thrips on daylilies. Then, hit the paper with these plant parts. Gently tip the paper to remove any bits of trash and then examine the paper in bright sunlight. Any thrips present will move around on the paper.

Control: Several naturally occurring enemies feed on thrips. As much as possible, you should stay away from insecticides that kill these helpful bugs that naturally lower thrips populations. Blue sticky traps will help protect daylilies from thrips. Paint cardboard or wooden boards blue and then coat them with petroleum jelly. Attach them to stakes and place them near the daylilies.

If serious damage is occurring, insecticidal soap or spinosad sprays are recommended. Spinosad is a foliar systemic insecticide that can penetrate the unopened flowers to give good thrips control. Always spray in the evening to lessen the spray impact on pollinating insects. As with any pesticide, read and follow all label directions and precautions.

Spider Mites with Two Spots (Tetranychus urticae): Daylilies can get attacked by this and other types of mites. Mites are not insects but are more closely related to spiders. They are very small, less than 1/50-inch long. They have piercing mouthparts that allow them to puncture plant tissue and suck plant sap. Mites tend to be more of a problem during hot, dry periods. Over time, some spider mites produce a fine web on leaves, which protects their eggs and young. With a light infestation, daylily leaves and flowers develop yellowish speckles. Partially because of the mite’s tiny size, this damage often goes unnoticed until the damage is more severe. With a heavy infestation, the speckles will run together, and entire leaves can become bleached and die. Along with leaf decline, growth is stunted.

Sampling: Like thrips, spider mites are very small and are difficult to detect before damage is obvious. To sample for mites on daylilies, follow the same procedure discussed in the thrips section above.

Control: Spider mites overwinter (survive the winter) on weeds, such as chickweed. Removing nearby weeds before spring growth is an important step in the control of spider mites. Insecticidal soap spray, if started early in the infestation, is effective at controlling spider mites. For more severe infestations, tau-fluvalinate or bifenthrin sprays will control spider mites. See Table 1 for examples of brands and products. As with all pesticides, read and follow all label directions and precautions.

Aphids: Various aphids can be pests on daylilies. Aphids are soft-bodied insects that vary in color from yellow-green to almost black. They are typically more of a problem during cool weather in the spring. They feed on leaves and flower buds by inserting their mouthparts and sucking plant sap. Their feeding can result in deformed leaves and small warty growths on flower buds. Most aphids excrete honeydew (a sugary liquid waste) after feeding on plant sap. A fungus known as sooty mold will grow on the honeydew, which will cause dark fungus growth on the leaves.

Control: Several naturally occurring enemies feed on aphids, including green lacewings and ladybird beetles (ladybugs). As much as possible, these predators should be allowed to reduce aphid populations. Because of their phenomenal reproductive rate, aphids are very difficult to control with insecticides. If a single aphid survives, a new colony can be produced within a short time. In addition, the use of contact insecticides may also kill the beneficial predators of aphids. Insecticidal soap sprays are a less toxic alternative that can help reduce aphid populations.

However, for more severe infestations, bifenthrin, cyfluthrin, lambda cyhalothrin, or permethrin sprays will control aphids. See Table 1 for examples of brands and products.

Slugs Their feeding results in ragged notches along leaf edges and sometimes holes in the middle of leaves. The appearance of shiny, slimy trails is a typical sign of their presence. Slugs and snails feed at night and hide during the day in moist areas.

Control: Remove their daytime hiding places by removing mulch and leaf litter near the base of the plant. Apply environmentally safe snail and slug baits (containing iron phosphate) near the beds. More information on control of slugs and snails and the safest baits is available in HGIC 2357, Snails & Slugs in the Home Garden.

Daylily Leafminer: The Ophiomyia kwansonis daylily leafminer was brought to the US from Japan and Taiwan around 2006 and has quickly spread across the eastern US. This is an adult leafminer fly. It is a small black fly that lays its eggs on daylily leaves in the spring. The small, pale yellow larvae then eat inside the leaves in mines that wind around and get wider as the larvae get bigger. The whitish mines remain visible throughout the life of the leaf, which makes infested daylilies unmarketable. This pest over-winters as small tan pupae, approximately the size of a grain of rice. Over-wintering occurs either near the base of the leaves or at the base of the plants.

Control: Prompt removal and disposal of infested foliage will reduce the spread of this pest. At the end of the season, remove and throw away all the dead leaves. This will help stop the pupae from overwintering and stop the spread of diseases like daylily leaf streak and daylily rust. Sprays to control the leafminer may affect natural predators and parasites that can reduce the number of leafminers.

Insecticides that control this leafminer are imidacloprid sprays or plant drenches, acephate sprays, or spinosad sprays. Spinosad is a natural insecticide that is the safest to use. It works like acephate on the leaves of plants to kill insects. This means it will penetrate the foliage to kill the larvae within the leaves. Spinosad is used to get rid of thrips, caterpillars, flies, and other insect pests, so it doesn’t hurt many beneficials as much. However, it is always best to spray late in the evening to reduce the impact on pollinating insects. Spray with spinosad as soon as symptoms of mining are noticed.

Table 1. Disease, Insect Pest, & Mite Control on Daylilies.

Active Ingredient	Examples of Brands & Products
Acephate	Bonide Systemic Insect Control Concentrate
Bifenthrin	Bifen I/T Concentrate
	Ferti-lome Broad Spectrum Insecticide Concentrate
	Hi-Yield Bug Blaster Bifenthrin 2.4 Concentrate
	Monterey Mite & Insect Control Concentrate
	Monterey Mosquito Control Concentrate
	Martin’s FLEE Ready to Use Yard Spray RTS
	Ortho Bug-B-Gon Insect Killer for Lawns & Gardens Conc.; & RTS1
	Ortho Outdoor Insect Killer Concentrate
	Ortho BugClear Insect Killer for Lawns & Landscapes Concentrate; & RTS
	Talstar P Concentrate
	Up-Star Gold Insecticide Concentrate
Chlorothalonil	Bonide Fung-onil Concentrate
	Ferti-lome Broad Spectrum Landscape & Garden Fungicide Concentrate
	GardenTech Daconil Fungicide Concentrate
	Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide Concentrate
	Ortho MAX Garden Disease Control Concentrate
	Southern Ag Liquid Ornamental & Vegetable Fungicide Concentrate
	Tiger Brand Daconil Concentrate
Cyfluthrin	Bayer BioAdvanced 24 Hour Lawn Insect Killer RTS
	Bayer BioAdvanced Complete Insect Killer for Soil & Turf I RTS1
	Bayer BioAdvanced Insect Killer for Lawns RTS1
	Bayer BioAdvanced Rose & Flower Insect Killer RTU2
Lambda Cyhalothrin	Spectracide Triazicide Insect Killer for Lawns & Landscapes Conc.; & RTS1
	Martin’s Cyonara Lawn & Garden Concentrate; & RTS1
	Martin’s Cyzmic CS Controlled Release Insecticide
Horticultural Oil	Bonide All Seasons Spray Oil Concentrate
	Ferti-lome Horticultural Oil Spray Concentrate
	Monterey Horticultural Oil Concentrate
	Safer Brand Horticultural & Dormant Spray Oil Concentrate
	Southern Ag ParaFine Horticultural Oil Concentrate
	Summit Year Round Spray Oil Concentrate
Insecticidal Soap	Bonide Insecticidal Soap RTU2
	Espoma Organic Insect Soap RTU2
	Garden Safe Insecticidal Soap Insect Killer RTU2
	Miracle Gro Nature’s Care Insecticidal Soap RTU2
	Natria Insecticidal Soap RTU2
	Natural Guard Insecticidal Soap Concentrate
	Safer Brand Insect Killing Soap Concentrate
	Whitney Farms Insecticidal Soap RTU2
Mancozeb	Bonide Mancozeb Flowable with Zinc Concentrate
	Southern Ag Dithane M-45
Myclobutanil	Ferti-lome F Stop Lawn & Garden Fungicide Concentrate
	Monterey Fungi-Max
	Spectracide Immunox Multi-Purpose Fungicide Concentrate
Permethrin	Bonide Eight Insect Control Vegetable, Fruit & Flower Concentrate
	Bonide Total Pest Control Outdoor Concentrate
	Bonide Eight Yard & Garden RTS1
	Hi-Yield Indoor/Outdoor Broad Use Insecticide Concentrate
	Hi-Yield Lawn Garden Pet & Livestock Insect Control Conc.
	Southern Ag Permetrol Lawn & Garden Insecticide Concentrate
	Tiger Brand Super 10 Concentrate
Propiconazole	Banner Maxx Fungicide
	Bonide Infuse Concentrate
	Ferti-lome Liquid Systemic Fungicide II Concentrate
	Martin’s Honor Guard PPZ
	Quali-Pro Propiconazole
Spinosad	Bonide Colorado Potato Beetle Beater Concentrate
	Bonide Captain Jack’s Deadbug Brew Concentrate; & RTS1; & RTU2
	Conserve SC Turf & Ornamental Concentrate
	Ferti-lome Borer, Bagworm & Leafminer Spray Concentrate
	Monterey Garden Insect Spray Concentrate
	Natural Guard Spinosad Bagworm, Tent Caterpillar & Chewing Insect Control Concentrate; & RTS1
	Ortho Insect Killer Tree & Shrub Concentrate
	Southern Ag Conserve Naturalyte Insect Control Concentrate
	Natural Guard Spinosad Soap RTU2
Tau-Fluvalinate	Bayer BioAdvanced 3-in-1 Insect, Disease & Mite Control Conc.; & RTS1; & RTU2 [with imidacloprid (an insecticide) and tebuconazole (a fungicide)]
	Bayer BioAdvanced 3-in-1 Insect, Disease & Mite Control I Conc.; & RTS1 [with Tebuconazole (a fungicide)]
Thiophanate Methyl	Cleary’s 3336-WP Turf & Ornamental Fungicide
	Southern Ag Thiomyl Systemic Fungicide
1RTS = Ready to Spray (a hose-end sprayer) 2RTU = Ready to Use ( a pre-mixed spray bottle)

Pesticides are updated annually. Last updates were done on 7/21 by Joey Williamson.

If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.

Joey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University

This information is given with the understanding that it is not meant to be biased. The Clemson University Cooperative Extension Service does not endorse any brand names or registered trademarks, and products or manufacturers that are not named are not meant to be biased either. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All pesticide use suggestions are only for South Carolina and were legal at the time of publication. However, state and federal regulatory agencies can change the status of registration and use patterns at any time. Follow all directions, precautions and restrictions that are listed.

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Foolproof Aphid Control and Prevention

How do you get rid of aphids on daylilies?

Mix up the ingredients in a spray bottle and wipe down or spray your daylilies’ leaves every day until the aphids are gone. Here are a few different recipes to try: Mix water and a few drops of dawn dish soap to create a mild soapy water solution. Mix one quart of water, a teaspoon of dish soap, and some cayenne pepper.

Do aphids damage daylily plants?

For the most part, aphids don’t cause severe damage to most trees or shrubs. However, individual daylily plants, are susceptible to irreversible harm. The aphid injects saliva into the leaf when it eats the sap, severely distorting the leaf leading to potential stunted plant growth. They sometimes carry plant viruses in their saliva as well.

How do you know if your daylily garden has an aphid infestation?

Still, there is another way to determine if your daylily garden has an aphid infestation. When aphids eat the plant sap, they produce a liquid waste known as “honeydew.” The insects leave behind this sugary substance and create the perfect breeding ground for sooty mold, a noticeable fungus.

Do aphids eat daylilies?

Daylilies are colorful perennials that brighten up any garden. They need lots of sunlight and love to care to thrive. Once planted, daylilies are easy to maintain and care for, adapting to their environment and using the sun to grow. Few insects can hurt daylilies, but aphids on daylilies can destroy an entire garden of them.