Crape myrtles (Lagerstroemia species) are popular ornamental trees known for vibrant summer blooms and attractive bark. Leaf curling often signals an underlying issue, indicating plant stress and requiring attention.
Understanding Crape Myrtle Leaf Curling
Leaf curling in crape myrtles protects against stressors. Under unfavorable conditions, leaves alter shape to minimize exposure or conserve resources. They curl inward to reduce surface area exposed to intense sunlight or dry winds, limiting water loss. This response helps the plant adapt.
Curling can also result from external agents like sap-sucking insects or chemicals. These disrupt cellular structure or nutrient flow, causing distorted growth. Observing curl type and symptoms helps diagnose the root cause. Leaf curling signals a disturbed internal balance, prompting investigation.
Identifying and Managing Pest-Induced Curling
Sap-sucking pests often cause crape myrtle leaf curling by extracting fluids and injecting growth-altering substances. This disrupts cell development, leading to deformed foliage. Pest identification is key to management.
Aphids
Aphids are small, pear-shaped insects, often green, black, or pink, found on new growth and leaf undersides. Their feeding causes young leaves to curl, yellow, and distort. They excrete honeydew, leading to sooty mold. A strong water stream dislodges them; insecticidal soaps or neem oil smothers them. Ladybugs help manage populations.
Whiteflies
Whiteflies are tiny, moth-like insects with powdery white wings that flutter when disturbed. They feed on leaf undersides, causing yellowing, curling, and premature drop. Like aphids, they produce honeydew, attracting sooty mold. Horticultural oils or insecticidal soaps control them; yellow sticky traps monitor and reduce adults.
Scale Insects
Scale insects appear as small, immobile bumps on stems and leaf surfaces. They feed by piercing tissues and sucking sap, causing yellowing, stunted growth, and leaf curling. Soft scales excrete honeydew; armored scales do not. Horticultural oils applied during dormant season or when young crawlers are active control species.
Spider Mites
Spider mites are microscopic arachnids thriving in hot, dry conditions. They cause stippling (tiny yellow or white dots) on leaves, with subsequent curling and bronzing. Fine webbing may be visible on leaf undersides or between branches in severe infestations. Regular overhead watering deters them; miticides may be needed for heavy infestations, particularly those resistant to water sprays.
Addressing Environmental Stress Causing Leaf Curling
Crape myrtles curl leaves in response to environmental stressors, adapting to protect from unfavorable conditions. Understanding these non-pest causes is crucial for plant health.
Water Imbalance
Both insufficient and excessive watering cause crape myrtle leaves to curl. Underwatering leads to leaves curling inward to reduce moisture loss, potentially crisping edges. Overwatering can cause root rot, impairing water uptake and leading to wilting and curling despite saturated soil. Establish a consistent watering schedule, check soil moisture, and ensure good drainage.
Temperature Extremes
Crape myrtles curl leaves when exposed to extreme temperatures. Intense heat, especially with drought, causes leaves to curl downward or inward to shield from sunlight and conserve moisture. Cold snaps or frost can damage leaf tissue, leading to curling and discoloration. Provide afternoon shade during heat waves or temporary covers during unseasonable cold to mitigate stress.
Nutrient Deficiencies
Nutrient deficiencies can cause leaf curling and discoloration. Magnesium deficiency might cause older leaves to curl and yellow between veins; iron deficiency leads to interveinal yellowing and curling on newer growth. A soil test identifies imbalances, guiding appropriate fertilizer application.
Chemical Exposure
Accidental herbicide exposure or improper pesticide application can severely stress crape myrtles, resulting in curled, distorted, or burned leaves. Herbicide drift from nearby lawns or gardens is a common cause, as small amounts have significant effects. Always apply garden chemicals carefully, following label instructions, and avoid spraying on windy days to prevent unintended contact.
Proactive Care for Healthy Crape Myrtles
Proactive care maintains crape myrtle health, defending against leaf curling and stress issues. A strong, well-cared-for plant is more resilient to environmental fluctuations and pests.
When planting, select a site with full sun (at least six hours daily) and well-draining soil. Proper planting sets the foundation for vigorous growth and reduces future stress. Consistent watering, especially during dry spells and establishment, ensures adequate moisture.
Regular fertilization, based on soil test results, provides nutrients for robust development and flowering. Pruning improves air circulation and light penetration, deterring pests and fungal issues. Inspecting crape myrtles for early distress signs allows timely intervention.