How do we treat crape myrtle bark scale on our HOA's crape myrtles?

By OurHOA · General information · Revised October 30, 2026

How an HOA board spots and treats crape myrtle bark scale: white felt and black sooty mold, soil drench timing, trunk washing, licensing and a sample year.

Part of the HOA board handbook: vendors, projects and upkeep.

The short answer

If your crape myrtles have white or gray crusty patches on the bark and the trunks are turning black, you probably have crape myrtle bark scale. It rarely kills a tree, but it makes the trunks, the mulch and the sidewalks underneath sticky and black, and it cuts down on blooms. The fix that works is a systemic insecticide applied to the soil around the base of each tree in spring, before the tree blooms, done by a licensed applicator. Washing the trunks before treatment and checking every new tree before it goes in the ground make the treatment go further. This is a recurring cost, not a one-time cure, so put it in the landscape contract with a line price per tree. Pesticide licensing rules vary by state and your governing documents decide who maintains which trees. Treat this guide as general education, not legal advice.

How to tell it is bark scale

Most boards hear about it first from an owner asking why the crape myrtles by the entrance are black. That black coating is sooty mold, a fungus that grows on the sticky honeydew the scale insects excrete. Texas A&M AgriLife Extension describes the adult scale as a felt-like white or gray crust, about 2 mm long, on anything from small twigs to large trunks. Crush one and it leaks a pink liquid that looks like blood. Clemson's Home and Garden Information Center says to look on stems, large twigs, branch crotches, pruning cuts and trunks, and that the scale rarely shows up on leaves. Two checks keep you from paying to treat the wrong problem: - Aphids also cause sooty mold on crape myrtles, but UF/IFAS notes that crape myrtle aphids feed on leaves and tender green shoots, not woody bark. White crusts on the bark mean scale. - Old crusts stay on the tree after the insects die. Scrape a few with a fingernail or a knife point. Live scales are moist and bleed pink; dead ones are dry and flaky. On big trees, look above head height too. UF/IFAS says most scales on large trees are likely to be on the upper branches and small twigs, and on the shaded underside of horizontal limbs.

Where it has spread and who should confirm it

The scale was first found in 2004 in Richardson, Texas, a Dallas suburb, and has since spread across the South. Clemson lists Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Georgia, North Carolina, Virginia and South Carolina. In Florida, UF/IFAS reported it in 2021 from a home landscape in Santa Rosa County, in the panhandle. Neither the Clemson nor the UF/IFAS distribution lists include Colorado. If you are in an area where it is already common, your contractor can confirm it on sight. If you are in Florida, or anywhere it has not been reported, send photos or a bagged sample to your county extension office first. UF/IFAS says that in an area with no prior report, the Florida Department of Agriculture's Division of Plant Industry has to confirm the specimen, and that new populations should be wiped out quickly, which can mean removing the infested plant rather than treating it.

The treatment that works, and when to apply it

Soil-applied systemic insecticides from the neonicotinoid group have given the best results in university trials. Texas A&M's fact sheet names clothianidin, dinotefuran, imidacloprid and thiamethoxam, applied to the root zone as a soil injection or a drench, and says to allow several weeks for the product to move through the tree. Clemson says a spring drench of dinotefuran or imidacloprid, as new growth begins, may control the scale for at least a year. The Williamson County AgriLife office recommends applying for heavy infestations from March through May, before new adults form under their waxy covers. Timing matters for a second reason. These products can be very toxic to bees, and crape myrtle flowers draw them. UF/IFAS says not to apply while the tree is in flower and to follow every pollinator instruction on the label. A spring soil treatment, finished well before bloom, meets both goals. Ask the applicator to log, for each tree: date, product, active ingredient, amount used and trunk size. Expect to wait. Texas A&M's City Bugs blog notes that control can take several weeks to show and that dead scales do not fall off on their own, so a crusty trunk in June does not mean the treatment failed. Do the fingernail test before you call the contractor back.

Washing, pruning and what not to spray

Washing. On heavily infested trees, Texas A&M recommends scrubbing the trunk and reachable limbs with a soft brush and a mild solution of dishwashing soap and water. It removes many females and egg masses and much of the black mold. It does not control the scale by itself. The Williamson County office adds that a power washer also works. This is a good job for a volunteer work day on small trees. Pruning. Clemson describes a rejuvenation option for badly infested shrub-form trees when the board does not want to use insecticides: cut the plant flush with the ground, keep three evenly spaced sprouts, mulch and fertilize, and expect flowers to return within about three years. Bag or burn the cuttings rather than leaving them for brush pickup, so crawlers are not carried to new trees. What not to spray. UF/IFAS warns that some common insecticides, pyrethroids for example, can make scale populations grow, because they do little to the scale and kill the lady beetles that eat it. Texas A&M says horticultural oil has not been shown to work well against this scale, though a dormant-rate winter oil on bark and crotches may help. Lady beetles, especially the twice-stabbed lady beetle, do eat the scale but usually arrive too late in the season to prevent the mold, so leave their pupae on the trunk alone.

Who may apply it in Texas, Florida and Colorado

Texas. Under Tex. Occ. Code 1951.003, treating pests or diseases of trees, shrubs or other plantings next to a residence or in a park for pay is structural pest control, and section 1951.301 requires a business license from the Texas Department of Agriculture. A mowing crew without that license should not be drenching your trees. Florida. Fla. Stat. 482.156 lets landscape maintenance workers with a limited certification apply pesticides to ornamental plants only if the label carries no signal word or the word 'caution', and only with handheld equipment or backpack sprayers. Check the signal word on the product your contractor plans to use and ask which license covers it. Colorado. Under C.R.S. 35-10-103, anyone in the business of applying pesticides for hire is a commercial applicator, and 35-10-106 sets insurance requirements. In every state, put the license number and the certificate of insurance in the file before work starts.

Put it in the contract and tell the owners

Count and number every crape myrtle on the common areas, mark which are infested, and note trunk size or height. Then add a line to the landscape or tree care contract: 'Contractor shall inspect all association crape myrtles for crape myrtle bark scale each February and report infested trees by number. Contractor shall apply a labeled soil systemic insecticide to the listed trees between [March 1] and [May 15], completing all applications before bloom, and provide a record of date, product, active ingredient and amount for each tree. Price per tree by size class: [ ].' Our guide on how to hire an HOA landscaping contractor covers bid sheets and certificates of insurance. Sample motion: 'Move that the association hire [company], license [number], to treat the [number] crape myrtles listed on the attached map for crape myrtle bark scale by soil application this spring, at a cost not to exceed $[amount].' Sample owner notice: 'The black coating on our crape myrtles comes from an insect called crape myrtle bark scale. This spring a licensed contractor will treat the association's trees at the base of each trunk. If the crape myrtles in your own yard have white crusty patches on the bark, treating them at the same time will help keep the scale from moving back onto common area trees.'

A sample year and the mistakes to avoid

January to February: inventory and inspection; wash the worst trunks. March to May: soil treatments, finished before bloom. June to July: fingernail test on treated trees; no repeat spraying on blooming trees. Late summer: watch for a second wave of crawlers, which Clemson notes peaks again in late summer, and update the map. Fall: price next year's work and add any newly infested trees. Our guide on how to plan an HOA tree maintenance program shows where this fits in the yearly tree budget. The mistakes that cost boards money: paying for leaf sprays to fix an aphid problem that is actually scale, spraying a general insecticide that wipes out the lady beetles, treating trees in full bloom, calling the treatment a failure because dead crusts are still on the bark, letting an unlicensed crew apply products, and planting new crape myrtles without checking the bark and pruning wounds at the nursery, which Texas A&M and UF/IFAS both recommend.

Sources

These guides are general education for HOA boards and residents, not legal, tax, or financial advice. Rules vary by state and by your community's governing documents - check with a professional for your situation.

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