Crepe myrtles are iconic, vibrant, flowering trees that line the streets of some of the country’s most beautiful neighborhoods. However, these classic Southern trees can become plagues with problems and left with untreated pests or diseases can surely lead to decline and possible death. No witchcraft or voodoo here! Proper care of your crape myrtles can not only enhance the natural beauty this species provides, but also a tree with longevity to be enjoyed for years to come.
Our professional MTS arborists have put together a list of common issues so you can catch warning signs early and we can help address issues before it’s too late. The Top 5 Crepe Myrtle Issues and Some Treatment Methods
The Top 5 Crepe Myrtle Issues
- Crape Murder
A common practice is to prune crape myrtles back very far because many feel this increases the magnificent flowers. While pruning can encourage more blooms, care must be taken for proper pruning at the right time of the season. Pruning crape myrtles right after bloom is the most recommended pruning time and proper pruning methods are encouraged to alleviate any stress the tree then experiences. Trees can experience stress? Yes, they do and whether related to weather conditions, lack of or too much rain, poor pruning or poor soils and more, these issues all cause stress to the tree. Stressors encourage pests and disease to become more prevalent when this occurs in many cases. - Cercospora Leaf Spots
Warning Signs: Cercospora leaf spots are yellow spots on the top of crepe myrtle leaves caused by fungus spores that grow underneath. This disease occurs during warm, humid months and can cause crepe myrtles to lose their leaves prematurely. - Aphid Infestations
Warning Signs: Crepe myrtle aphids are yellow-green with black spots. They extract the sap from the crepe myrtle leaves, leaving yellow spots and a sticky liquid that attracts mold, fungi, and other insects. Treatment: MTS professional PHC specialists will apply appropriate products at best times to minimize the damage aphid infestations can begin to cause within your tree. - Japanese Beetle Infestations
Warning Signs: Japanese beetles can damage crepe myrtle trees from above and below ground. They’re typically active from May to August and leave signs of damage on the leaves. Treatment: MTS professional PHC specialists have organic and synthetic options to minimize adult leaf feeding beetles that skeletonize your tree’s leaves making it unsightly. - Crape Myrtle Bark Scale
Warning Signs: Crepe myrtle bark scale is a relatively new problem for crepe myrtles in the United States. This pest was recently introduced by way of Asia and looks like gray scales coating the tree branches. Bark scale damages the tree and can cause stress to the tree which can cause decline and possibly death. Treatment: MTS Professional PHC specialists have many options for minimizing this pest population and can help provide the best option.
In addition to these, the article notes many diseases and pests, including powdery mildew, sooty mold, rust, and various leaf spots and aphid-related issues. The secret to breaking the crepe myrtle curse is prevention and early detection. For example, start with sunny spots with good airflow and low moisture rates, maintain regular trimming, and prune infected branches early to save the tree. A free tree assessment with an expert arborist can help determine the health of your crepe myrtles.
Understanding Purple Leaves on Crepe Myrtles
Crepe myrtles (Lagerstroemia indica) are popular in many landscapes, and purple foliage can be a feature of certain cultivars or a sign of stress. New leaves often emerge purple-red due to anthocyanins, protecting against UV and cold, and they green up in 2-4 weeks. If leaves remain persistently deep purple across the canopy, this can signal stress from factors like phosphorus deficiency, drought, or environmental conditions. Several cultivars are bred for colored foliage, while others naturally show purple new growth that fades as leaves mature.
Common causes of purple leaves include:
- New growth with purple coloration that normalizes with time.
- Phosphorus shortage causing dull purple or purpling in lower leaves; remedy: balanced NPK fertilization (e.g., 10-20-10) in spring and, for phosphorus, superphosphate at 50 g/m².
- Frost damage in colder zones leading to purple leaves due to cellular injury; prevention: mulch roots with 5-7 cm of organic matter.
- Drought stress prompting purpling as the plant conserves water.
- Aphid feeding causing distortion and purpling; inspect soil and consider treatments if infestation is present.
For ornamental value, select cultivars bred for colored foliage and ensure they’re suited to your USDA hardiness zone. Proper site selection, soil preparation, adequate sunlight (minimum 6 hours), and good airflow are essential to prevent stress that can lead to purple leaves and other problems.
Diagnosing Browning and Leaf Problems
Brown leaf edges or tips can indicate soluble salt buildup, often from municipal water or excessive fertilizer. Test soil salinity and leach salts with deep, thorough watering, then switch to lower-salt fertilizers and maintain mulch away from the trunk to prevent salt migration. Cercospora leaf spot is another common cause of browning, with small purple-gray spots on lower leaves that spread upward. Fungicide applications at first sign, improved air circulation, and pruning to remove infected tissue are recommended.
Brown margins can also arise from root problems, including girdling or buried root flares, compacted soil, or poor drainage. A University of Florida study noted that many symptomatic crepe myrtles have buried root flares, leading to oxygen deprivation and secondary fungal invasion. Root management may involve exposing root flares, pruning circling roots, vertical mulching for aeration, and ensuring well-drained soil. Avoid overwatering, which exacerbates root rot. Pruning should be done to improve airflow and remove dead wood, not to fix browning caused by other issues.
Seasonal timing matters: spring browning can indicate frost or Cercospora onset, while summer browning often signals salt stress or drought. Fall browning is often normal senescence, but rapid, uniform browning before October suggests stress factors such as excessive nitrogen, herbicide drift, or girdling roots. A targeted, pattern-based approach helps-observe margins, spots, timing, and texture to diagnose issues accurately and intervene precisely.
Care Principles and Remedies
Right plant, right place matters. Choose cultivars rated for your USDA Zone and known disease resistance. Planting: dig a hole 2× wider than the root ball but no deeper, backfill with native soil, and avoid amendments that retain too much water. Water wisely with drip irrigation on a timer for pre-dawn delivery. Mulch: keep mulch 3 inches away from the trunk and limit total depth to 3 inches to prevent moisture excess and salt movement. Prune with purpose: remove crossing, diseased, or inward-growing branches in late winter; never engage in crape murder.
Soil and water management are foundational. Crepe myrtles thrive in well-drained, slightly acidic loam (pH 5.5-6.5). Test drainage if you notice prolonged soggy soil: dig a 12-inch hole, fill with water, and time drainage. If drainage exceeds four hours, amend accordingly at planting with up to 20% composted material. Mature trees require deep, infrequent watering (about 1 inch every 7-10 days during drought) rather than daily sprinkling.
When pests or diseases are present, an integrated approach works best. Plant Health Care (PHC) programs that combine systemic and foliar treatments can target pests like bark scale and aphids while preserving beneficial insects. For Cercospora, begin fungicide applications at first leaf emergence in spring and continue as needed, with improved air circulation to reduce humidity. For powdery mildew, ensure full sun exposure, good airflow, and consider resistant cultivars; multiple applications may be required in shady, damp locations.
Leadership by observation and early action is key. Regular assessments and timely interventions help prevent decline. If browning or leaf drop persists despite proper watering and pruning, consider professional assistance to diagnose and address root issues or disease. A thoughtful, site-aware approach will help Crepe Myrtles remain beautiful and healthy for decades.
Practical notes and recommendations
Observe patterns and timing: margins suggest water or salt issues, while centers indicate fungal or pest issues. Check for webbing or specks on the undersides of leaves, and look for sticky honeydew that indicates aphids or scale. If root problems are suspected, inspect the trunk flare and surface roots, and consider root pruning or aeration measures as described above. Soil health, drainage, and sun exposure are foundational to preventing purple foliage and browning problems.
Right cultivar selection and proper pruning are essential for ongoing health and appearance. Use cultivars with known disease resistance and ensure the plant is suited to your climate zone. Regular maintenance, smart irrigation, and attentive monitoring will help your crepe myrtles stay vibrant and resilient year after year.
