Crape myrtle (Lagerstroemia spp.) is a popular ornamental tree in urban landscapes across the southern United States. Known for its vibrant summer blooms and striking bark, this tree has become a favorite for homeowners and landscapers alike. However, in recent years, it has been increasingly threatened by a pest known as crape myrtle bark scale (Acanthococcus lagerstroemiae), which can significantly affect the tree’s health and aesthetic value.
Identification
Crape myrtle bark scale is a small, soft-bodied insect that primarily attaches itself to the bark of crape myrtle trees. Here’s what you need to know to identify it:
– Appearance: The adult scale appears as small, white to gray, felt-like encrustations on the tree’s bark. Juvenile stages look pinkish before developing the white outer coating.
– Location: They tend to cluster in crevices, along the branches, and on the trunks of crape myrtles. Infestations often begin near pruning cuts or wounds on the tree.
– Signs of Infestation: Aside from the the visible presence of scales, you may notice black sooty mold on the bark. This mold grows on the honeydew produced by the scale, leading to an unsightly, sticky appearance. Another sign of infestation is reduced flowering and weakened overall tree health due to nutrient loss.
Life Cycle
Understanding the life cycle of crape myrtle bark scale is crucial for effective treatment. These pests produce multiple generations per year, and adult females lay eggs that hatch into mobile crawlers. These crawlers spread over the tree and can migrate to other nearby crape myrtles. The warm, humid climates of southern regions allow for rapid reproduction and spread, making infestations more likely in these areas.
Impact on Crape Myrtles
While crape myrtle bark scale does not directly kill the tree, its presence weakens the plant by feeding on the sap. This process can result in:
– Stunted Growth: Trees may experience reduced vigor and slow growth, especially in younger or stressed crape myrtles.
– Aesthetic Damage: The black sooty mold that grows on the honeydew produced by the scale can coat the bark, branches, and even leaves, leading to a significant loss in the ornamental value of the tree.
– Reduced Flowering: Infested trees often produce fewer or less vibrant blooms due to the energy diverted from flowering to combating the pest.
Control and Management
Managing crape myrtle bark scale involves a combination of cultural practices, mechanical removal, and chemical treatments.
Cultural Practices
– Proper Pruning: Pruning crape myrtles properly can help reduce infestations. Remove dead or heavily infested branches and avoid topping, which stresses the tree and makes it more susceptible to pests.
– Tree Health: Keeping your crape myrtles healthy through proper watering, mulching, and fertilization helps them withstand pest pressure.
Mechanical Control
– Scrubbing: For light infestations, you can manually remove scales by scrubbing the bark with a soft brush and mild soap solution to remove the insect’s protective coating. This can help expose the insects to natural predators and chemical treatments.
Chemical Control
– Horticultural Oils: Applying horticultural oil during the dormant season can suffocate the scales before they become active in spring. This method is effective and relatively safe for the environment.
– Systemic Insecticides: For more severe infestations, systemic insecticides like imidacloprid or dinotefuran can be applied to the soil or sprayed onto the tree. These chemicals are absorbed by the tree and affect the scale when they feed on the sap. It is best to consult with a certified arborist or a professional tree care company before applying any chemicals to ensure proper timing and dosage.
Preventing Future Infestations
Preventing crape myrtle bark scale from returning requires consistent monitoring and proactive care:
– Regular Inspections: Check your crape myrtles regularly, especially in spring and summer, to spot early signs of scale infestations.
– Beneficial Insects: Encourage the presence of natural predators, like lady beetles and lacewings, that feed on the scale’s eggs and crawlers. Avoid broad-spectrum insecticides that could harm these beneficial insects.
– Proper Spacing: When planting new crape myrtles, ensure they are spaced adequately to promote good air circulation, which can reduce the likelihood of pest infestations.
Conclusion
Crape myrtle bark scale is a serious pest that can detract from the beauty and health of your crape myrtles if left untreated. With proper identification, management, and prevention strategies, you can protect your trees and maintain their stunning appearance. If you’re dealing with a severe infestation or unsure how to treat your trees, it may be time to consult with an ISA Certified Arborist for expert advice and care.
At Barren Tree Solutions, we specialize in diagnosing and treating tree pests like crape myrtle bark scale. Contact us today to schedule a consultation and keep your crape myrtles healthy and beautiful year-round.