Crape Myrtle Care Tips

Sooty Mold

Identify: Leaves and stems may appear black and dirty due to sooty mold, a fungus that grows on the honeydew produced by sap-sucking insects like aphids, scales, mealy bugs, and white flies. This mold signals an underlying insect infestation.

Treatment: Sooty mold is unsightly but harmless to plants. Address the issue by controlling sap-sucking insects like aphids. Encourage beneficial insects like lady beetles or remove aphids with a strong water spray. To clean sooty mold, rinse leaves with a dish soap solution (4 oz. per gallon of water), wait a few minutes, then rinse thoroughly.

Powdery Mildew

Identify: White or gray powdery patches appear on leaves, flowers, and shoots, causing distortion and stunted growth. Flowers may not open. The disease thrives in shady, damp, crowded areas with poor air circulation, especially in humid nights and dry, mild days common in spring and fall.

Treatment: To control powdery mildew, plant resistant crape myrtle varieties in full sun and remove sprouts (suckers) at the base, as they are highly susceptible. Prune diseased twigs and branches if only a few shoots are infected to prevent fungal spread. If chemical control is needed, use a fungicide with myclobutanil, propiconazole, thiophanate-methyl, or copper. Follow label instructions, as multiple applications may be necessary.

Leaf Spot

Identify: This disease occurs in warm, moist conditions, causing yellow spots (⅛ to¼ inch) on the upper leaf surface and white-grey fungal growth on the underside. It can lead to significant defoliation in late summer and fall, especially insusceptible cultivars.

Treatment: Ensure good air circulation and avoid overcrowding plants. If the disease is severe enough to require chemical treatment, thiophanate-methyl ormyclobutanil, used for powdery mildew, will help control Cercospora leaf spot. Follow all label instructions when applying chemicals.

Bark Scale

Identify: Crape myrtle bark scale (CMBS) appears as white or gray waxy crusts on stems, large twigs, and trunks, particularly at branch crotches and pruning sites. They feed under loose bark, making control difficult. These scales produce large amounts of honeydew, leading to black sooty mold growth on the plant’s leaves, branches, and trunk.

Treatment: The most effective chemical control for crape myrtle bark scale is a spring soil drench with dinotefuran. This systemic insecticide, available as concentrates or granules, moves through the plant and provides control for up to a year. Apply in spring when new growth begins. Alternatively, spray for crawlers in late April-May and again in late summer. Follow all label instructions when applying chemicals.

Crape Myrtle Aphids

Identify: Crape myrtle aphids are small, pale yellowish-green insects with blackspots on their abdomens, ranging from 1/16 to 1/8 inch in length. Aphids feed on tender new leaves by sucking plant sap, which is high in sugar. This results in the excretion of honeydew, a sugary liquid that can coat the leaves. High aphid populations can cause extensive honeydew buildup, which attracts sooty mold fungi and various insects like ants, wasps, and flies.



Treatment: Aphids reproduce quickly, making them difficult to control with insecticides. Even if one survives, a new colony can form rapidly, and insecticides may harm beneficial predators. If necessary, homeowners can use insecticides like insecticidal soap, horticultural oil, pyrethrins, neem oil, permethrin, cyfluthrin, cyhalothrin, acephate, or malathion. A spring soil drench of imidacloprid can also control aphids and provide longer-lasting protection. Always follow label instructions when using pesticides.