Crape myrtles (Lagerstroemia spp.) are cherished for their vibrant summer blooms and striking bark. However, these beautiful trees and shrubs face a growing threat from crape myrtle bark scale (Acanthococcus lagerstroemiae). This invasive pest, first identified in the U.S. in 2004, can cause significant damage if left unmanaged. In this blog, we’ll explore what crape myrtle bark scale is, how it affects your plants, and the best ways to manage and prevent an infestation.
What is Crape Myrtle Bark Scale?
Crape myrtle bark scale (CMBS) is a sap-sucking insect that belongs to the Eriococcidae family. Native to Asia This invasive insect has been spreading across the United States, causing concern for gardeners, landscapers, and arborists alike. CMBS primarily infests crape myrtles but can also affect other plant species, such as persimmons and pomegranates.
Identification
Identifying CMBS early is crucial for effective management. Here are the key characteristics:
- Appearance: Adult scales are small, about 2 mm long, and covered in a white or gray, waxy coating. They often appear as white, felt-like encrustations on the bark, branches, and twigs.
- Eggs and Nymphs: Eggs are pink and hidden beneath the waxy coating. Nymphs, or crawlers, are tiny, pinkish-red, and mobile, spreading to new areas of the tree.
- Sooty Mold: A black, sooty mold often develops on the honeydew excreted by the scales, covering leaves, stems, and even the trunk in black.
Impact on Crape Myrtles
CMBS can significantly impact the health and aesthetic value of crape myrtles:
- Reduced Vigor: By feeding on the plant’s sap, CMBS weakens crape myrtles, reducing their overall vigor. This can lead to fewer blooms and slower growth.
- Aesthetic Damage: The presence of scales and the black sooty mold they cause can make crape myrtles look unsightly, detracting from their ornamental value.
- Increased Vulnerability: Stressed plants are more susceptible to other pests and diseases, compounding the impact of a CMBS infestation.
Managing Crape Myrtle Bark Scale
Managing CMBS requires a combination of cultural practices, biological controls, and, in some cases, chemical treatments.
1. Cultural Practices
- Regular Monitoring: Regularly inspect your crape myrtles, especially during the growing season, to catch any signs of CMBS early.
- Pruning and Disposal: Prune out heavily infested branches and dispose of them properly to reduce the scale population. Do not compost infested material, as it could spread the pest.
- Maintaining Plant Health: Healthy plants are more resistant to pests, so ensure your crape myrtles receive adequate water, nutrients, and care.
2. Biological Control
- Natural Predators: Encourage beneficial insects like lady beetles and parasitic wasps, which naturally prey on CMBS. Avoid using broad-spectrum insecticides that can harm these helpful predators.
3. Chemical Control
- Insecticidal Soaps and Oils: These can be effective against the crawler stage of CMBS. Thorough coverage is essential, so apply these treatments during the growing season when crawlers are most active.
- Systemic Insecticides: Products containing imidacloprid or dinotefuran can be applied as a soil drench or trunk injection. These treatments are absorbed by the plant and can provide long-term control. It’s important to follow label directions carefully and apply these treatments in late spring or early summer for best results.
Preventing Future Infestations
Preventing future infestations of CMBS involves being proactive:
- Inspect New Plants: Before planting new crape myrtles or other susceptible species, carefully inspect them for signs of CMBS.
- Quarantine: If you’re bringing new plants into your landscape, consider quarantining them for a period to ensure they are pest-free.
- Community Awareness: CMBS can easily spread between plants and properties, so educating your neighbors and community about the signs of infestation can help protect everyone’s landscape.
Crape myrtle bark scale is a serious pest that requires prompt and effective management to protect your crape myrtles. By staying vigilant, practicing good cultural care, and employing appropriate biological and chemical controls, you can keep your crape myrtles healthy and beautiful. As with any pest, early detection and intervention are key to minimizing damage and ensuring the long-term health of your landscape.
If you suspect a CMBS infestation or need assistance with treatment, don’t hesitate to consult with a professional arborist or your local extension service. Together, we can preserve the beauty and health of our crape myrtles for years to come.