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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.
What to Spray on Dahlias for Bugs: A Comprehensive Guide
As a dahlia lover and avid gardener, I know firsthand how frustrating it can be when pesky bugs start munching away on those vibrant blooms. Dahlias are absolutely stunning flowers, but their beauty seems to act like a beacon for all kinds of creepy crawlers looking for their next meal. If left unchecked, these unwanted guests can quickly damage leaves, stunt growth, and completely ruin the flowers.
The good news is there are several effective sprays and techniques you can use to protect your dahlias and keep them looking their best all season long. In this comprehensive guide, I’ll walk you through the most common dahlia pests, the symptoms they cause, and share my proven tips for controlling them organically and safely. Consider this your handy troubleshooting reference for diagnosing and treating any bug issues on your prized dahlias.
Common Dahlia Bugs and How to Identify Them
Before you can treat a pest problem, it’s important to properly identify the culprit. Here are some of the most notorious bugs that go after dahlias and how to recognize the damage they cause
Aphids – These tiny, soft-bodied insects come in a variety of colors like green, black, or red. They feed on the sap inside the plant, causing curled, stunted, or distorted growth. Aphids secrete a sticky substance called honeydew, so you may see a shiny coating on the leaves or petals.
Thrips – Tiny winged insects that rasp holes in leaves and petals. You’ll notice silvery patches, discolored spots, or streaks on the foliage and blooms. They tend to hide deep inside flower buds.
Spider Mites – Too small to spot with the naked eye, these microscopic pests form white webs on the undersides of leaves. Leaves take on a speckled or bronzed look.
Japanese Beetles – Metallic green and copper beetles that chew holes in the foliage. They skeletonize the leaves, leaving only the veins behind.
Slugs and Snails – While not insects themselves, these slimy creatures can cause just as much damage. Look for large ragged holes chewed in the foliage and trails of shiny slime across leaves and petals.
Earwigs – Dark reddish-brown insects with distinctive pinchers on their abdomen. They chew holes in leaves, petals, and flower buds, usually at night.
Now that you know what to look for, let’s explore the safest and most effective sprays and treatments to banish these bugs for good. I’ll provide organic solutions as well as recommendations for when a chemical spray is needed for severe infestations.
Organic Sprays and Treatments
For mild pest issues, there are several organic options that can control bugs without harming beneficial pollinators like bees and butterflies or leaving chemical residue behind. Here are some all-natural methods I’ve had great success with over the years:
Insecticidal Soap – This is my go-to for soft-bodied insects like aphids, thrips, and spider mites. The soap disrupts the pests’ cell membranes on contact. Spray every 5-7 days until the infestation clears.
Neem Oil – Extracted from the seeds of the neem tree, this natural oil repels and kills many common garden pests. It’s great for prevention and maintenance. Mix with a bit of insecticidal soap and spray weekly.
Diatomaceous Earth (DE) – This powder made from crushed fossils cuts into the exoskeleton of soft-bodied bugs, causing dehydration. Dust it around the base of plants and the soil to create a protective barrier. Reapply after watering or rain.
Garlic Spray – Blend garlic cloves with water and a bit of mild soap to create a spray that repels aphids, beetles, and other pests. Be sure to spray underneath leaves and on stems.
Sticky Traps – These yellow cards lure in flying pests and keep them from reaching your plants. Position them just above the dahlia canopy to catch thrips, aphids, whiteflies, and leafhoppers.
Row Covers – Covering plants with lightweight fabric rows creates a protective barrier against most bugs while still allowing air and light through. Install them over hoops for easy access.
Hand Removal – For large, slow pests like slugs, simply picking them off by hand and dropping them into soapy water can greatly reduce damage. Check plants daily.
When Organic Isn’t Enough: Recommended Chemical Sprays
I always try organic solutions first, but some severe infestations call for the use of an occasional chemical spray as a last resort. Here are the most effective options to consider:
Pyrethrin-based Sprays – Derived from chrysanthemum flowers, these sprays are plant-based but still pack a punch on contact. They work quickly against aphids, beetles, earwigs, and most flying insects. Reapply weekly.
Neem Oil Concentrates – More potent concentrated formulas containing higher percentages of neem oil (70% or more) provide added insecticidal benefits compared to pure neem oil alone.
Insecticidal Soap Concentrates – Like pure insecticidal soap sprays, concentrated formulas allow you to mix stronger solutions to battle tougher infestations of soft-bodied bugs.
Imidacloprid – A selective systemic insecticide that is taken up by the plant’s roots and makes its tissues and fluids toxic to sucking and chewing bugs like aphids, thrips, and beetles. Use as a soil drench or granular treatment.
Bifenthrin – This synthetic pyrethroid insecticide offers longer residual effects than natural pyrethrin for lasting control of mites, beetles, earwigs, caterpillars and other pests.
Whichever spray you choose, always follow the label directions closely and take proper safety precautions. Avoid applying chemical solutions during the heat of day or when pollinators are active. Target sprays specifically on affected plants rather than general spraying.
With a combination of preventative organic treatments and selective use of commercial sprays when absolutely necessary, you can keep those gorgeous dahlias pest-free and ready to show off! Just a bit of diligence and prompt action when bugs first appear will allow your flowers to thrive all season long. Don’t let a few little critters ruin your dahlia fun!
Treating Pests that Affect Dahlias
Proper plant care is the best line of defense against dahlia insect pests, as healthy dahlia plants are more pest-resistant. Water properly and apply fertilizer carefully according to label directions. Keep dahlia beds clear of leaves and other plant debris, which provide hiding places for slugs, snails, earwigs, and other pests. Similarly, limit mulch depth to no more than 3 inches (8 cm.), especially if you notice silvery slug and snail trails. Keep weeds pulled in the area around your dahlias. Prune any damaged plant parts. Large pests like slugs and caterpillars are easy to remove by hand. Remove the pests and drop them in a bucket of soapy water. Evenings or early mornings are the best times for this task, when slugs and caterpillars are more active. Grab a flashlight and be sure to wear gloves to protect your hands. In some cases, wood ashes and diatomaceous earth create scratchy barriers that keep slugs at bay. If caterpillars remain a major problem, consider using Bacillius thuringenesis (Bt), a natural bacteria. When caterpillars eat the bacteria, the toxins give the pests a deadly tummy ache. (Keep in mind that although caterpillars and slugs have similarities, they are very different pests. Bt won’t help alleviate a slug problem, and wood ashes and diatomaceous earth are unlikely to discourage caterpillars.) Avoid pesticides, which are dangerous for bees and other beneficial insects. Many pests, including spider mites, aphids, and thrips are easily treated with an insecticidal soap spray. Reapply every week to ten days if you continue to notice pests on your dahlias. Seek out safe alternatives, such as chemical-free slug pellets. Consider ways to attract birds, frogs, and toads to your yard. They’ll do a great job at keeping caterpillars, slugs, and other pests in check.
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?
Some general insects that attack dahlias are leaf miners, stem borers, aphids, and thrips. Preventative measures are always better than trying to get rid of pests once they arrive. Recommended sprays: BioAdvanced 3-in-1, Monterey Garden Insect Spray, Orthene, Neem Oil, Sevin-5, Organocide, and Malathion.
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.
How do you get rid of thrips on a dahlia plant?
Spraying is necessary to stay ahead of pest issues. Some insects that can attack dahlias are leaf miners, stem borers, aphids, and thrips. Recommended sprays: Bayer (BioAdvanced) 3 in 1, Monterey Garden Insect Spray, Orthene, Neem Oil, Sevin-5, Organocide, and Malathion.
Do dahlias attract bugs?
Dahlias, those vibrant and captivating blooms in our gardens, are a joy to behold. However, they often attract a variety of pesky bugs that can dampen their beauty. In this comprehensive guide, I’ll explore the most effective sprays and methods to keep your dahlias bug-free.
What insecticides kill dahlias?
Earwigs: Keep your dahlia beds clean and set up traps. Now, let’s dive into some specific insecticides that work wonders on dahlias: Contains: 0.5% Spinosad. Effective Against: Caterpillars, leafminers, thrips. Usage: Mix 4 tablespoons with 1 gallon of water and spray thoroughly. Ideal For: Aphids, leafhoppers, mealybugs, thrips, whiteflies, mites.
When should I spray my dahlias?
Timing is everything when it comes to pest management! Here’s when I recommend spraying dahlias: Early spring: Make a dormant spray of horticultural oil plus lime sulfur to smother overwintering pests on tubers before sprouting. When shoots emerge: Spray emerging growth with insecticidal soap to control early aphids and thrips.
What can I use on my dahlias?
When looking for a product to use on or around your dahlias, anything safe for vegetables, roses, or other flowering plants will work fabulously for your dahlias. We have a wonderful line of products on our website or on our farm in our Pest & Disease Control section. Spraying is necessary to stay ahead of pest issues.
How do you treat Dahlia fungus?
To treat Dahlia fungus, spray your affected plants with water once a day for three days straight and prune away affected parts. Check back after a couple days to see if this method helped control the infestation.