Spirea problems can make your beautiful bush look sick, with brown spots, curling leaves, or stunted growth. If you’re seeing these issues, don’t worry, you’re not alone. Most spirea problems are easy to spot and fix. Keep reading to learn what’s wrong with your spirea and how to make it healthy again.
Spirea Leaves Curling: Aphid Problems and Solutions
Aphids, also called "plant lice," are soft-bodied, pear-shaped sucking insects about the size of the head of a pin. They sometimes cluster in large masses on tender new leaves and buds of spirea. Their feeding retards plant growth, and causes the leaves to curl and turn yellow. Ants, attracted by the aphids' honeydew secretions, wander over the plants and protect the aphids from natural predators.
Check stem tips and leaf undersides for small groups of aphids. Mash isolated clusters between thumb and forefinger or spray light infestations with a vigorous water spray 3 times, every other day or so, in the early morning. Eliminate nearby ant nests if possible. If the aphids are all over the shrub, spray them directly with an insecticide product featuring insecticidal soap according to label instructions. Since most types of spirea rarely have pest problems, consider if yours may be under stress which makes it vulnerable, and address this situation.
If you see your spirea leaves curling or turning yellow, it's a strong sign that aphids are present and damaging the plant. Acting fast can help prevent further issues with your spirea leaves. To learn more about how to control aphids, check out Controlling Aphids
Did you know? Spirea leaves curling can quickly get worse if aphids are ignored, so regular checking is essential. According to the University of Minnesota Extension, timely intervention can save your plant from permanent damage
Spirea Pests: Leaves Rolled into Tubes by Leafrollers
Leafrollers are the larvae of small moths. They protect themselves while feeding by rolling leaves into tubes and binding them with strands of silk. The oblique-banded leafroller sometimes attacks spirea leaves. Adult moths are brown or gray, 1/4 to 1/2 inch long. Larvae are dark to light green or cream to yellow caterpillars, 3/8 to 1 3/4 inch long.
If there are not too many leafrollers, handpick the larvae in their leafy tubes and crush them. Control larger infestations by spraying or dusting foliage with a product containing Bacillus thuringiensis, or Bt, as soon as you see the feeding caterpillars and the rolled leaves on your spirea. They will ingest the bacterium and later die. Follow the instructions on the package label. Because Bt is rapidly inactivated by sunlight and rain, you may have to repeat the spray.
Sometimes, leafroller damage shows up as black spots on spirea leaves, which can confuse gardeners looking for spirea pests and diseases. Always check for rolled leaves and silk webbing if you notice unusual spots.
For more tips on keeping your plant strong and healthy (so it can fight off pests and diseases), see our full Spirea Care Guide.
Note: Quick action is important, leafroller outbreaks can spread rapidly and cause permanent leaf damage if untreated. According to the University of California’s Integrated Pest Management program, using Bt is an effective, eco-friendly solution.
Click here for more information about Controlling Caterpillars
Why Is My Spirea Dying? Yellow Leaves and Root Knot Nematodes
Spireas infested with Southern root knot nematodes look sickly, wilted, or stunted. They develop yellowed or bronzed foliage, then they decline slowly and die. All these symptoms result from nematodes, whitish, translucent, roundworms about 1/50 to 1/10 inch long, which attack their roots. Infested roots are poorly developed, show knots or galls, and may be partially decayed. Nematode activity is most obvious in hot weather, when wilting shrubs fail to recover from the heat.
Control nematodes by adding lots of compost (especially leaf mold) to the soil around the spirea plants to encourage beneficial fungi that attack nematodes. Pour diluted liquid fish emulsion onto the soil around affected roots. It is toxic to nematodes. Remove dead or dying shrubs with the soil around their roots and discard them in the trash.
If you’re noticing a yellow leaf spirea or seeing that your spirea is dying, root knot nematodes are a likely culprit. Wondering “why is my spirea dying?” Look for yellow leaves and stunted growth, these are classic signs of this problem.
For more help with spirea dying and other common issues, check out Spirea Shrubs Are Turning Brown and Spirea Leaves Are Droopy And Drying Up.
Spirea Yellow Leaves and Scale: Spotting and Treating Scale Insects
The first sign of a scale attack is that some of the spirea’s leaves turn yellow, then drop off. Infested new growth in spring is stunted and severe infestations can kill a young shrub. Some species of scale excrete honeydew, which attracts ants and encourages the growth of sooty mold on the leaves. If you notice any of these symptoms, look for the scale insects themselves. They suck sap from plant foliage protected by rounded waxy shells which make telltale bumps on stems and leaf undersides. The bumps may be white, yellow, or brown to black, and are about 1/10 to 2/5 inch in diameter.
Simply scrape small patches of bumps off spirea leaves or stems with your fingernail or a cotton swab dipped in rubbing alcohol. Spray more heavily infested shrubs with light horticultural oil according to the directions of the label to smother the insects and any eggs.
Scale can be one of the main reasons for spirea yellow leaves, as the pest drains sap and weakens the plant. If left untreated, you might notice spirea dead branches or even see damage along spirea branches. Because scale is part of common spirea pests and diseases, it’s important to act quickly.
If your spirea yellow leaves are also drooping or drying up, see our tips in Spirea Leaves Are Droopy And Drying Up. For more advice on preventing leaf loss and spotting early signs of trouble, visit Spirea Leaves Are Turning Brown And Dropping.
Click here for more information on Controlling Scale
Spirea Dead Branches? Fire Blight Warning Signs
This bacterial disease is spread by insects and rain. It is one of the most destructive diseases of some spireas, blighting young twigs and limbs. Leaves die, hang downward and cling to the blighted twigs. Dying branches, which appear scorched, are conspicuous during the summer and ruin the shrubs' ornamental value. Leaf drop is often a primary symptom of this disease.
Prune out infected branches, cutting at healthy tissue well below blighted areas. Spray shrubs with a streptomycin antibiotic wettable powder product to protect blossoms. Do not over fertilize, because excess nitrogen makes the shrub more blight-prone. This disease is rarely serious unless the spirea is planted near pears, apples or hawthorns which are also susceptible to it.
Spirea dead branches are a classic sign of fire blight, especially when you also see leaf drop or scorched-looking twigs. If you’re noticing spirea branches dying back or the whole shrub declining, this is often the cause. Serious cases of fire blight can leave your spirea dying, especially if other pests and diseases are stressing the plant.
When dead branches or odd symptoms appear, it’s worth comparing with issues like Spirea Have Some Dead Branches With Small Blue Spots or spotting patterns similar to Spirea Stems Are Covered In Bright Green Bumps.
Spirea Powdery Mildew: White Coating and How to Treat It
Powdery mildews caused by various fungi sometimes attack some kinds of spireas, coating their leaves and growing tips with whitish patches. While this disease is not fatal, it does mar the appearance of the shrub. Since control is time consuming, most homeowners choose to live with it.
To protect healthy foliage on an infected shrub from the spread of the mildew, spray it thoroughly with a general garden fungicide containing sulfur according to instructions on its label. Collect and discard all dead leaves, branches and mulch in the fall to reduce overwintering mildew spores. Spread fresh mulch for the winter.
Spirea powdery mildew usually shows up as a white or gray film on the leaves, and in severe cases you might notice spirea yellow leaves or overall decline. Like other spirea pests and diseases, mildew can be persistent—sometimes even leading to spirea dying if left untreated.
Click here for more information on Controlling Fungal Disease
Spirea Leaf Spot: What Causes Yellow or Brown Blotches?
Yellow, brown or black blotches, which frequently run together, appear on leaves affected with fungal leaf spot. Heavily infected leaves turn yellow or brown and fall prematurely. Some fungal spots are surrounded by flecks or black dots, the spore-bearing fruiting bodies. You can easily distinguish leaf spot diseases from spots caused by winter injury or ice that focuses sunlight, burning the leaves.
Cool, moist weather promotes fungal diseases, especially when new leaves are developing. Pick off and discard infected leaves. Shake out all fallen and diseased leaves from the center of the shrub and destroy them. Cut down and trash (do not compost) seriously infected shrubs together with the soil ball. Mulching helps prevent splash-borne infection in outdoor plantings. Spray healthy foliage every 7 to 10 days with a general garden fungicide to protect it from the spread of the infection.
Spirea leaf spot can show up as red spots on spirea leaves, yellow leaves, or blackened areas. All of these are common signs of leaf spot diseases in spirea, so check carefully for new discoloration.
Click here for more information on Controlling Fungal Disease
Spirea Yellow Leaves? Could Dog Urine Be the Cause?
Dog urine is mildly toxic to most ornamental plants, as well as lawns. It may discolor spirea foliage and even kill lower branches that dogs visit repeatedly. Spray vulnerable foliage with an anti-transpirant spray to provide some ground-level protection. Also try screening the plants or spraying foliage with a repellent spray. Prune out damaged areas to stimulate regrowth of new, healthy stems and foliage.
If you notice spirea yellow leaves, dog urine may be the cause - especially if the burn is mostly on the lower parts of spirea branches. Severe or repeated exposure can result in spirea dead branches, or even spirea dying if the damage is not managed.
For more information see the file on Dealing With Dogs and Cats
Frequently Asked Questions on Spirea Problem
What kills spirea?
Spirea can be killed by digging out the roots, smothering with a tarp, or applying herbicides like glyphosate or triclopyr, especially right after cutting the stems. For aggressive types like Japanese spirea, repeat mowing and trench barriers help control spread. Organic sprays or pest damage may weaken the plant, but full removal usually requires physical or chemical methods.
Can spirea get too much sun?
Yes, especially in hot climates, spirea can suffer from too much direct sun. Signs include:
- Leaf scorch or browning edges
- Wilting despite watering
- Stunted or crispy growth
To prevent damage, offer afternoon shade, maintain soil moisture, or use a shade cloth in peak heat.
How do you revive spirea?
Yes, you can actually bring spirea back from decline with the right steps:
- Cut back dead or diseased wood first
- Prune lightly if growth is weak—or cut down to 3–6" for full renewal
- Clear dense areas to boost airflow
- Water deeply when soil is dry 4–6" down
- Add balanced fertilizer in spring
- Ensure soil drains well and adjust light if needed
These steps help restore growth and revive a stressed or aging spirea.
Will my spirea come back?
Yes, spirea is a hardy perennial that regrows each spring, often even after heavy pruning or drought. As long as the roots are healthy, it can bounce back from winter dieback, browning, or damage. Even if cut to the ground, many spirea will push out fresh shoots when warm weather returns.
What does overwatered spirea look like?
Overwatering can quickly stress spirea, showing up through clear warning signs:
- Yellowing lower leaves
- Wilting even when soil feels wet
- Mushy, dark, or foul-smelling roots
- Soggy or heavy soil around the plant
- Slowed or stunted growth
If you spot these, reduce watering, improve drainage, and trim any rotten roots to help your plant recover.
Can I use neem oil as fungicide?
Neem oil acts as a natural fungicide for spirea and can help manage mild fungal issues like powdery mildew.
It’s especially useful for:
• Powdery mildew control
• Preventing fungal spread on leaves
• Repelling aphids and soft-bodied pests
It may not be enough for:
• Severe or systemic fungal infections
• Root rot or advanced blight
Apply during cooler hours and avoid spraying during bloom to protect pollinators.
How can you tell the difference between a fungal leaf spot and a bacterial leaf spot in spirea?
Check the spot’s texture and color, these signs help tell them apart:
| Feature | Fungal Leaf Spot | Bacterial Leaf Spot |
|---|---|---|
| Appearance | Dry, brown with clear margins | Wet, translucent, often irregular shape |
| Texture | May show spores or rings | Glossy or glassy look when moist |
| Halo | Rare | Often has a yellow halo |
| Spread | Expands slowly, may form rings | Can rapidly merge into dead patches |
When unsure, lab testing or expert help can confirm the diagnosis.
