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Dahlias are stunningly beautiful, relatively easy plants that produce clusters of luscious blooms from early summer through late fall, but discovering dahlia insect pests on your prized plants is a frustrating, disheartening experience. Read on to learn about insects that like dahlias, and about treating pests that affect dahlias.
Dahlias are absolutely gorgeous flowers that add a pop of color and beauty to any garden However, their good looks also make them a target for bugs and pests. As a dahlia lover, you want to keep your plants healthy and pest-free But you also want to avoid using harsh chemicals. So what should you spray for organic pest control?
Here is a guide to the most common dahlia pests and the best organic sprays and methods to get rid of them,
Prevent Bugs from Reaching Dahlias
The most foolproof organic pest control for dahlias is preventing bugs from ever touching the plants in the first place.
Organza bags or sleeves are the best option for this. Slip the bags over the dahlia blooms when they are still in the green bud stage. The fine mesh will block nearly all pests while still allowing sunlight and air circulation.
Organza bags work great if you mainly grow dahlias for cutting But they may look a little silly in an ornamental garden
Control Specific Dahlia Pests
If you opt not to use organza bags, you’ll need to identify the pests in your garden and use sprays targeted to each type. Here are some common dahlia bugs and organic control methods.
Grasshoppers
Grasshoppers are one of the toughest dahlia pests to control organically. They move fast and have hard bodies that resist sprays.
One organic solution is attracting birds to your garden. They love munching on grasshoppers. Add a bird bath or other water source. Chickens will also eat grasshoppers if your plants are large enough to withstand chicken activity.
For sprays, botanical insecticides with pyrethrins can kill grasshoppers. But you have to spray carefully and thoroughly since grasshoppers are quick to flee.
Thrips
Tiny thrips are a major nuisance for dahlias, especially light colored varieties. They feed on leaves and petals, leaving behind silver streaks and scarring.
Use yellow or blue sticky traps around plants to monitor for thrips. Control them with regular applications of insecticidal soap or neem oil sprays. Spinosad and pyrethrin insecticides also kill thrips. Rotate between different products to prevent resistance.
Bagging flowers provides the best thrip protection. Avoid growing early dahlias which are most prone to thrips.
Tarnished Plant Bugs
These small bugs pierce dahlia leaves and stems to suck out sap. They spread diseases as they move between plants.
Hang up yellow sticky traps in the plant canopy to catch tarnished plant bugs. Use traps carefully to prevent harming other animals.
Insecticidal soaps, neem oil, pyrethrins, and spinosad will also control plant bugs when applied regularly.
Leafhoppers
Like plant bugs, leafhoppers transmit dahlia diseases. They are tiny green, yellow, or brown insects that jump when disturbed.
Use yellow sticky traps as well as sprays of insecticidal soap, neem, or spinosad to control leafhoppers. Their populations explode in hot, dry weather.
Cucumber Beetles
These round-bodied beetles devour dahlia blooms and quickly defoliate plants. Watch for the yellow and black striped adults as well as the red or yellow spotted cucumber beetle larvae.
Neem oil, spinosad, pyrethrins, and insecticidal soaps can be sprayed to kill adults. Apply parasitic nematodes to soil to kill larvae. Completely covering flowers with bags provides the best protection.
Avoid planting dahlias near cucurbits, which attract cucumber beetles.
Aphids
Aphids cluster on dahlia shoots and undersides of leaves. These soft-bodied insects suck plant sap, causing stunted growth and discolored foliage.
Blast aphids off plants with a strong spray of water. Follow up with insecticidal soap or neem oil to kill them. Introduce ladybugs and other beneficial insects that feast on aphids.
Spider Mites
Hot, dry conditions cause microscopic spider mites to multiply rapidly. They form webs on dahlia leaves and cause stippling damage.
Apply sprays of neem oil, insecticidal soap, or horticultural oil to suffocate mites. Also release predatory mites to consume spider mites.
Dahlia Pest Spray Rotation
Whichever pests you battle, be sure to rotate between different spray products. Using the same pesticide repeatedly leads to resistance.
Ideally, alternate between products with these different active ingredients:
- Neem oil
- Insecticidal soaps
- Spinosad
- Pyrethrins
- Horticultural oils
This keeps the bugs guessing and avoids spraying any single pesticide too frequently. Carefully follow all label instructions for best results.
Maintain Plant Health
The best defense is a good offense when it comes to dahlia pest control. Healthy, vigorous plants can withstand more insect damage without suffering.
- Give dahlias full sun and high quality growing medium.
- Water and fertilize regularly to promote growth.
- Prune off any dead or diseased material immediately.
- Weed the dahlia bed to eliminate pest hiding spots.
With preventive measures and targeted organic sprays, you can enjoy gorgeous, pest-free dahlias. A garden teaming with beneficial insects and birds will also help reduce pests naturally.
Bugs Eating My Dahlias!
Below are the most common insect pests affecting dahlia plants in the garden:
- Thrips – Slender pests with fringed wings, Thrips damage plants by puncturing the leaves and sucking out the juices. Although thrips rarely kill dahlias, they can affect the appearance by causing stippled leaves, leaf drop and stunted growth. Pesticides aren’t usually helpful because the pests move from plant to plant so quickly.
- Spider mites – About the size of a tiny speck of sand, tiny spider mites are difficult to see with the naked eye. You can locate the pests with a magnifying glass, but a magnifying glass usually isn’t necessary because you will notice telltale strands of thin webbing on the leaves. Spider mites are often more apparent during dry, dusty weather.
- Snails and Slugs – Slugs and snails are capable of doing tremendous damage to dahlias and other plants. However, they are easy to spot; they chew large holes in leaves, and they leave slimy, mucous tracks wherever they go.
- Caterpillars – (the larval stages of moths and butterflies) Caterpillars leave no slime, but like slugs, they chew holes in the leaves. They often roll themselves up in leaves, and rolled, curled foliage is a dead giveaway that caterpillars have been feasting on your dahlias.
- Earwigs – Small, brown bugs with evil-looking pincers, earwigs aren’t as intimidating as they look. These dahlia insect pests are active during the nighttime hours and tend to remain hidden during the day. Keep in mind that pesticides are ill-advised. Although earwigs aren’t pretty, they do a good job at keeping aphids and other more harmful pests under control. Trap them with a rolled up newspaper or a short length of old garden hose.
- Grasshoppers – While not a major pest of dahlia, grasshoppers do occasionally feed on the plants leaves. Using nosema locustae is a safe way to get rid of these insects.
Dahlias 101 – Spraying
FAQ
What is the best insecticide for dahlias?
Recommended sprays: BioAdvanced 3-in-1, Monterey Garden Insect Spray, Orthene, Neem Oil, Sevin-5, Organocide, and Malathion. All organic sprays tend to work best for preventative care but are not as effective in treating a problem that already exists.
How do I keep bugs from eating my dahlias?
Keeping your dahlias consistently watered can help discourage them. Insecticidal soaps can temporarily reduce an outbreak. Get more information about this pest and how to control it in this article from the Missouri Botanical Garden: Controlling Thrips Outdoors.
What spray to use on dahlias?
Broad spectrum spinosad-based spray that controls most thrips, bores, leafminers, caterpillars, & moths. Works well for dahlias and other flowering plants.
Can I spray soapy water on dahlias?
If it is aphids, spraying them with water mixed with a little bit of dawn dish soap will kill them but not harm your dahlia!