Are Crepe Myrtles Invasive? Everything You Need to Know

Are Crepe Myrtles Invasive?

Yes, Crepe Myrtles are considered invasive in Maryland.

The introduction of the crepe myrtle bark scale insect has necessitated increased maintenance and pesticide use.

They can be fatal to trees and also infest other plants.

It is recommended to use native alternatives and implement control measures to lessen their impact.

Key Points:

  • Crepe Myrtles are considered invasive in Maryland.
  • The introduction of crepe myrtle bark scale insect has led to increased maintenance and pesticide use.
  • They can be fatal to trees and infect other plants.
  • It is advised to use native alternatives and implement control measures to reduce their impact.
  • The crepe myrtle bark scale insect has made crepe myrtles more troublesome to handle.
  • The negative effects of crepe myrtle invasion in Maryland can be minimized with proper management and alternative options.

Did You Know?

1. Crepe myrtle trees are native to East Asia, specifically China, Korea, and Japan.
2. The name “crepe myrtle” derives from the delicate, crinkled texture of its flowers, which resembles crepe fabric.
3. Crepe myrtles are commonly found in warmer regions and are well-suited to the southern United States due to their high tolerance to heat and drought.
4. Although crepe myrtles can spread and reseed themselves, they are not considered invasive species. Invasive plants tend to outcompete and harm native plants, whereas crepe myrtles coexist harmoniously with other flora.
5. Crepe myrtle wood is highly valued by woodworkers due to its beautiful grain, durability, and resistance to rot. It is commonly used to create furniture, cabinetry, and decorative items.

Introduction To Crepe Myrtles In Maryland

Crepe Myrtle (Lagerstroemia indica) is a flowering tree that is commonly found in landscapes across Maryland. This tree is admired for its stunning bark and its ability to thrive in various environmental conditions.

  • The Crepe Myrtle is easy to maintain.
  • It adds a touch of elegance and color to any garden or outdoor space.
  • Its popularity stems from its beautiful blooms.
  • It also provides shade and privacy.

“The Crepe Myrtle is a beloved flowering tree in Maryland, known for its stunning bark and versatile nature. Its easy maintenance, vibrant blooms, and ability to provide shade and privacy make it a popular choice for gardens and outdoor spaces.”

The Threat Of Crepe Myrtle Bark Scale

The Crepe Myrtle (specifically Lagerstroemia indica), a popular flowering tree known for its many desirable qualities, is facing a significant threat: the Crepe Myrtle bark scale (Acanthococcus lagerstroemiae). This invasive scale insect feeds on the sap of Crepe Myrtle and other plants, causing extensive damage and potentially even death to the trees.

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The presence of the Crepe Myrtle bark scale was first documented in the United States in 2004, specifically in central Texas. Since then, it has rapidly spread to various states, including Virginia, Delaware, and Maryland.

To summarize:

  • The Crepe Myrtle is a flowering tree with many desirable qualities.
  • The Crepe Myrtle bark scale is an invasive scale insect that feeds on the sap of Crepe Myrtle and other plants.
  • It was first observed in the United States in central Texas in 2004.
  • The insect has since spread to states like Virginia, Delaware, and Maryland.

“The presence of the Crepe Myrtle… potentially even death to the trees.”

Characteristics And Behavior Of Crepe Myrtle Bark Scale

The Crepe Myrtle bark scale is a small insect, measuring no more than 2 millimeters in length. Once the female scales attach themselves to a twig or branch, they do not move, while the winged males fly to the females to mate. This scale insect can be found anywhere on the twigs or branches, but they tend to cluster around pruning cuts. One of the notable characteristics of the Crepe Myrtle bark scale is its ability to produce a sticky secretion called honey dew, which attracts other insects and can result in the growth of sooty mold.

The scale insects have multiple generations in a year, ranging from two to four, increasing the chances of infestation and the need for maintenance. It is crucial to note that this invasive pest is not specific to Crepe Myrtle alone; it has also been found on other plants such as American beautyberry. Additionally, there are up to 30 different plants that could potentially serve as hosts for the Crepe Myrtle bark scale, including persimmon and soybeans.

Impacts Of Crepe Myrtle Bark Scale On Trees And Plants

The presence of the Crepe Myrtle bark scale can have severe consequences for ornamental trees and plants. In extreme cases, the infestation can be fatal, leading to tree decline and eventual death. Furthermore, the honey dew secreted by the scale insects attracts other insects, which can further exacerbate the problem. The accumulation of honey dew can also result in the development of sooty mold, causing aesthetic issues and potentially impeding the tree’s ability to photosynthesize.

  • The Crepe Myrtle bark scale infestation can be fatal for trees.
  • Insects are attracted to the honey dew secreted by the scale insects.
  • The accumulation of honey dew can lead to the development of sooty mold.

Note: The presence of Crepe Myrtle bark scale has negative consequences for the health and appearance of trees and plants.

Management And Control Of Crepe Myrtle Bark Scale In Maryland

The management and control of the Crepe Myrtle bark scale require diligent monitoring and proactive measures. Certified arborists can inspect the trees and apply appropriate control methods. One method is to wash off the branches and twigs with a strong stream of water from a garden hose, effectively removing the scale insects and their sticky secretions. Alternatively, pesticides such as horticultural oil, insecticidal soaps, and growth-regulating pesticides can be employed to control the scale insects.

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However, it is essential to exercise caution when using neonicotinoid insecticides as they can harm pollinators. Therefore, these insecticides should only be applied by professionals who are knowledgeable about their safe and effective use. Regular monitoring and prompt action are necessary to prevent and mitigate the impact of the Crepe Myrtle bark scale on ornamental trees and plants in Maryland.

Note: Neonicotinoid insecticides should only be applied by professionals who are knowledgeable about their safe use.

Bullet points for monitoring and control:

  • Inspect trees regularly for signs of Crepe Myrtle bark scale.
  • Wash off branches and twigs with a strong stream of water to remove scale insects and their secretions.
  • Consider using horticultural oil, insecticidal soaps, or growth-regulating pesticides as control measures.
  • Exercise caution when using neonicotinoid insecticides to avoid harming pollinators.

Through careful monitoring and appropriate control measures, it is possible to protect Crepe Myrtles and ensure their continued contribution to the natural beauty of Maryland’s landscapes.


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Frequently Asked Questions

What are the disadvantages of crape myrtles?

One of the major disadvantages of crape myrtles is their susceptibility to bark scale infestations. These invasive insects not only damage the trees by feeding on them but also create a favorable environment for the growth of black sooty mold. This mold not only ruins the appearance of the tree but can also hinder its overall health and vitality, affecting its ability to thrive. Additionally, controlling the infestation can be a challenging and time-consuming task, requiring regular monitoring and potentially the use of pesticides, which may not be ideal for those seeking more natural gardening approaches.

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Are crepe myrtles roots invasive?

Crepe myrtle trees have non-invasive roots that make them a suitable choice for planting near sidewalks. Unlike many other tree species, crepe myrtles do not cause damage or lift sidewalks with their root systems. This lack of invasive roots adds to the appeal of crepe myrtles as sidewalk margin trees.

Does crepe myrtle spread?

Yes, crepe myrtle does have the potential to spread. At maturity, the common crape myrtle can reach a height of 15–25′ and a spread of 6–15′. Its ability to spread adds to its overall charm and versatility. As it grows, it can occupy a larger area, creating a beautiful and impactful presence in gardens and landscapes. Its spreading nature allows it to fill empty spaces and contribute to a visually appealing and well-rounded environment.

What’s wrong with crepe myrtles?

While crepe myrtles (Lagerstroemia indica) are generally low-maintenance trees, they can suffer from a few common issues. Powdery mildew, a fungal infection, can appear as a white, powdery substance on the leaves and stems, affecting their overall health. Cercospora leaf spot is another problem that can cause black or brown spots on the leaves, leading to defoliation if left untreated. Additionally, aphids and Japanese beetles may infest crepe myrtles, causing leaf damage and overall stress to the tree. Lastly, sooty mold can develop on the sticky honeydew secreted by aphids, leaving a black, velvety coating on the leaves.

References: 1, 2, 3, 4

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