Crape Myrtle Bark Scale: White Spots and Black Sooty Mold

White spots on Crape Myrtle bark: is it bark scale?

Crape myrtle bark scale usually appears as small white or gray bumps attached to the bark. They can cluster in branch crotches, pruning cuts, under loose bark, along twigs, and on shaded sides of branches. At first, the specks may look like harmless residue, but they stay fixed to the bark and multiply.

The second clue is often black sooty mold. The scale insects feed on plant sap and release sticky honeydew. Sooty mold grows on that honeydew, so bark, leaves, patio furniture, cars, or pavement below the tree can become dark and sticky.

A heavy infestation can reduce flower number, flower cluster size, and overall vigor. It rarely kills a healthy tree quickly, but it can make a Crape Myrtle look dirty, weak, and less floriferous for more than one season.

How to tell bark scale from aphids or ordinary sooty mold

Sooty mold is not the root cause. It is a surface fungus growing on sugary insect waste. To fix the problem, find the insect producing the honeydew.

• Bark scale: white or gray felt-like bumps on trunks, branches, and twigs.
• Aphids: small soft insects mainly on tender leaves and shoot tips.
• Sooty mold: black coating on leaves, bark, and nearby surfaces.
• Powdery mildew: white powder on leaves and buds, not fixed scale bumps on bark.

Press one white bump with a fingernail or a small tool. Bark scale may release a pinkish fluid when crushed. That is a strong sign that the white material is not dust, lichen, or leftover spray.

Why does crape myrtle bark scale spread?

The pest spreads because the young mobile stage, called crawlers, moves to new bark and twigs before settling down to feed. Once they attach, they become harder to reach with simple contact sprays.

Infestations can also arrive on nursery plants or spread between nearby trees. Low-level infestations are easy to miss because the early white specks may be hidden in bark crevices. By the time black mold is obvious, the insect population may already be established.

Shaded, crowded, or poorly maintained trees often look worse because the bark stays protected and the canopy dries slowly. Trees in full sun may still get bark scale, but infestations are often easier to notice and manage early.

How to get rid of crape myrtle bark scale?

Begin with inspection and cleaning. Look closely at the trunk, lower limbs, branch joints, pruning scars, and the underside of horizontal branches. Mark the most infested areas so you can check them again after treatment.

For a small or reachable tree, scrub the trunk and limbs with a soft brush and mild soapy water. This can remove many female scales and egg masses. Rinse afterward and avoid harsh pressure washing, which can injure the thin bark.

Cleaning improves appearance, but it is usually not enough by itself for a heavy infestation. When scale is established, a properly timed insect control plan is often needed.

• Light infestation: scrub reachable bark, monitor crawlers, and repeat checks.
• Moderate infestation: combine cleaning with horticultural oil or insecticidal soap when crawlers are active.
• Heavy infestation: consider a labeled systemic treatment during active growth.
• Large mature tree: professional treatment may be safer and more effective.

Always follow the product label. Avoid spraying open flowers with insecticides that can harm pollinators. If using a systemic product, apply it only as directed and at the proper season, because the tree must be actively moving water for root-applied treatments to work well.

When is the best time to treat bark scale?

Treatment timing matters. Contact products are most effective against crawlers, the young stage that moves before settling. Once scale insects are protected under waxy coverings, they become harder to kill from the outside.

Use double-sided tape on small branches if you want to monitor crawler activity. When tiny crawlers appear on the tape, that is a better time for contact products than treating randomly.

Systemic soil treatments are usually applied while the tree is leafed out and actively growing. They can take weeks to move through the plant, so they are not an instant cosmetic fix. The black mold already on the bark may remain even after the insects are controlled.

How do you remove black sooty mold from Crape Myrtle?

Black sooty mold fades slowly after honeydew stops. If the scale insects are still feeding, washing the mold alone will only give temporary improvement.

For reachable areas, wash bark and leaves with mild soapy water, then rinse with clean water. Work gently. The attractive peeling bark is part of the plant’s value, so aggressive scraping can cause unnecessary damage.

Large trees may stay stained for a while. Rain, sun, and normal bark shedding help reduce old mold over time. The real sign of progress is not perfectly clean bark on day one; it is less sticky honeydew, fewer new scale bumps, and cleaner new growth.

Can bark scale stop a Crape Myrtle from blooming?

Yes, a heavy infestation can reduce bloom quality. Scale insects remove sap, and the honeydew-sooty mold layer can cover leaves and stems. Over time, the tree may produce fewer flowers or smaller flower clusters.

Still, no blooms can have other causes, including too much shade, late pruning, winter injury, or repeated topping. If white scale bumps and black mold are present, treat the insect problem first. If the bark is clean, the bloom issue may need a different diagnosis.

How can you prevent bark scale from returning?

Prevention depends on early detection. Check Crape Myrtle bark several times during the growing season, especially around branch crotches and shaded limb undersides. A few white specks are much easier to manage than a trunk coated in scale and mold.

• Inspect new plants before buying, especially the trunk and branch joints.
• Keep trees in full sun where possible.
• Prune for structure and airflow, not severe topping.
• Remove suckers and crowded shoots that hide pests.
• Control ants when needed, because they can protect honeydew-producing insects.
• Recheck treated trees the next season even if they look cleaner.

If one tree in a landscape has bark scale, inspect nearby Crape Myrtles too. Early infestations can be hard to see, and treating only the worst-looking tree may leave a hidden source nearby.

Long-term control is usually a process, not a single cleaning. Once the insect population drops and the tree is growing strongly again, new bark and foliage should look cleaner, and bloom performance should improve.