Crepe myrtle (Lagerstroemia indica) is an ornamental tree valued for its long-lasting summer flowers and distinctive bark. When bark shedding occurs, homeowners often worry if the tree is healthy or suffering from pests or disease. Peeling or splitting bark may be a normal sign of maturity or an indication of an underlying problem. Understanding the visual differences between natural exfoliation and damage is key to maintaining the tree’s health.
Natural Bark Exfoliation
The bark shedding on a Crepe Myrtle is a healthy, natural characteristic of the species and is not a cause for concern. This process, known as exfoliation, occurs as the tree grows rapidly and the outer layer of bark becomes restrictive. The tree sheds this old, thin bark in irregular, peeling strips.
The newly exposed wood underneath is smooth and reveals a beautiful, mottled pattern. These colors can range from light gray and tan to striking shades of cinnamon, cream, and reddish-brown. This unique, multi-colored trunk is one of the tree’s most prized features, especially during the winter.
Identifying Crepe Myrtle Bark Scale
If the bark is shedding and the trunk is covered in a black residue, the cause is likely Crepe Myrtle Bark Scale (CMBS), an invasive pest. This scale appears as small, white or gray, felt-like encrustations that cluster in branch crotches and on the bark. When crushed, these insects often exude a pinkish, blood-like liquid, which is a key diagnostic sign.
CMBS insects feed by sucking sap, leading them to excrete a sticky, sugary substance called honeydew. This honeydew becomes a breeding ground for sooty mold, a black fungus that covers the bark and leaves. The presence of this sooty mold is often the first sign that alerts homeowners to a scale infestation.
Environmental Stress and Physical Damage
Bark splitting or peeling not associated with CMBS can result from sudden environmental shock or physical injury. One common cause is freeze damage, or frost cracks, which occur when temperatures fluctuate sharply during late winter or early spring. This rapid change causes the trunk’s wood and bark to contract and expand at different rates, resulting in long, vertical cracks, often on the southwest side.
Physical damage, particularly to the base, can cause irregular wounds that expose the sensitive cambium layer beneath the bark. Repeated injuries from string trimmers or lawnmowers around the root flare are a common problem for young Crepe Myrtles. These wounds compromise the tree’s vascular system and leave it vulnerable to disease and decay.
Corrective Action and Prevention
Addressing a CMBS infestation requires a systemic approach to control the insects feeding on the tree’s sap. The most effective method is a soil drench application of a systemic insecticide, such as dinotefuran or imidacloprid, applied to the root zone in late winter or early spring. For immediate aesthetic improvement, use a soft brush and a mild solution of dish soap and water to gently scrub the scales and sooty mold from the trunk.
Preventing non-pest damage focuses on protecting the bark and promoting steady growth. To prevent mechanical injury, establish a mulch ring around the tree’s base, avoiding the trunk, to keep lawn equipment away. To reduce the risk of frost cracks, avoid fertilizing the tree late in the growing season, which stimulates tender growth susceptible to cold.