Coneflowers are hardy plants that add bold colors and height to beds and borders and make stunning mass plantings. These perennials are very low maintenance, and established plants need little care to thrive. Pests can infest coneflowers, causing extensive damage and destroying these lovely flowering plants. Learning the signs of bugs and how to prevent infestation will keep your coneflowers growing and thriving.
Photo courtesy of Joe Boggs
Common Coneflower Pests
Whiteflies
Known as sweetpotato whiteflies or silverleaf whiteflies, these tiny insects have yellow bodies and white wings. Whiteflies are sap suckers that suck nutrients out of plants like coneflowers. Large colonies can stunt plant growth, and cause leaves to fall off. The insect’s waste, known as honeydew, can cause black sooty mold.
Treating Whiteflies on Coneflower
Remove damaged foliage and blooms to clean up the plant and direct energy into new growth. Treat silverleaf whiteflies by spraying the plants with water to remove the insects at the first sign of infestation. Follow up with insecticidal soap. Repeat this treatment for several weeks, even if you do not see whiteflies or damage. The goal is to remove adult insects as well as larvae and eggs, so continued treatment is necessary.
Preventing Whiteflies on Coneflower
Prevent whiteflies on coneflowers by preemptively spraying the plants with insecticidal soap. If you have had trouble with this pest in the past, proactively spraying plants is your best chance at prevention. Helpful insects like ladybugs eat whiteflies, so do not remove any ladybugs you find on your plants.
Aphids
Greenflies and blackflies are the most common types of aphids. These pests also suck sap from the plant, causing foliage to wither and die from lack of nutrition. Curling, discolored leaves, stunted growth, and leaf drop as signs of aphid damage. These coneflower pests also produce honeydew that can attract ants and other pests and fungus.
Treating Aphids on Coneflower
The first step to treating aphids on coneflowers is to remove damaged sections, including parts covered in honeydew. Prune damaged growth and spray the plant with water to clean it as best as possible. Spray the coneflower with insecticidal soap or horticultural oil to kill any aphids, larvae, or eggs still on the plant. Continue to spray the plant for a few more weeks to ensure all of the aphids are gone.
Preventing Aphids on Coneflower
The most effective way to prevent aphids is to periodically spray the plant with water to knock any insects off the plant. Spray plants early in the morning to give the foliage time to dry off before evening. You can also spray the plants with insecticidal soaps or neem oil.
Japanese Beetles
Japanese beetles are about half an inch long and have a copper-colored back and iridescent shimmer. These are flying insects that feed on foliage. Irregular-shaped holes in leaves are a sign of Japanese beetles. These insects are out during the day and are often seen crawling and feeding on the plants. Japanese beetles can do a lot of damage quickly and strip a plant of viable foliage.
Photo by Joshua Mayer, unedited, Flickr, Copyright CC BY-SA 2.0
Treating Japanese Beetles on Coneflower
At-home Japanese beetle treatment for coneflowers can vary. The easiest and quickest way to treat Japanese beetles is to pluck them from the plants as you see them. You can brush them into a jar of soapy water, drowning them. You can also treat Japanese beetles by spraying the insects with insecticidal soap. The beetle needs to be sprayed directly with the soap to die, so just spraying the plant is not effective at treating Japanese beetles.
Preventing Japanese Beetles on Coneflower
Japanese beetles lay their eggs in the ground, and that is where their larvae grow. Getting rid of the larvae will erase the Japanese beetle population. Applying milky spore to your lawn will eliminate Japanese beetle larvae. Milky spore is a bacteria that kills Japanese beetle larvae when ingested. This product only targets Japanese beetles, and it can take a few years for it to build up in the soil to be effective; however, the results can last for decades.
Eriophyid Mites
Eriophyid mites are tiny parasites that live inside flower buds, feeding on the unopened bloom. Signs of eriophyid mite damage include stunted growth and flowers that are damaged and distorted upon opening. The mites are tiny and measure just 1 mm long, making them hard to see with the naked eye.
Photo courtesy of Joe Boggs
Treating Eriophyid Mites on Coneflower
Treat eriophyid mites on coneflowers by spraying the plant with horticultural oil or insecticidal soap. Continue to spray the plant for several weeks to ensure all of the mites, their eggs, and larvae are gone. Remove and destroy damaged growth to clean up the plant. Fertilize the coneflower after pruning to encourage new healthy growth. The entire plant may need to be removed and destroyed in extreme infestations.
Preventing Eriophyid Mites on Coneflower
Prevent eriophyid mites on coneflowers by removing debris from the ground surrounding the plant and proactively spraying the plant with insecticidal soap. Preventative measures are only necessary if you have had trouble with eriophyid mites in the past or if you suspect an infestation is developing.
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