Crape myrtle Lagerstroemia Propagation Crape myrtle is usually propagated by softwood stem tip cuttings collected during the warm season, using very tender wood with red or pink colored wood. Under intermittent mist, the cuttings should root in 8-15 weeks. Pests and Diseases The current Insect Management Guide for Commercial Foliage and Woody Ornamentals can be found at http://edis.ifas.ufl.edu/ig012. The current Professional Disease Management Guide for Ornamental Plants can be found at http://edis.ifas.ufl.edu/pp123. Crape myrtle aphid Recognition: Crape myrtle aphids are 1/8 inch long, pear-shaped, pale yellow and have two cornicles (or "tail-pipes"). The winged forms have black markings on their wings. They are found mostly on the undersides of the leaves. Aphids secrete honeydew on which sooty mold grows prolifically, often the first evidence that the aphids are present. Their feeding may cause distortion of new growth. Contributing factors: Crape myrtle aphids are host specific, and appear each year in late spring, remaining Sooty Mold until the leaves drop in the fall. Powdery mildew resistant varieties of crape myrtle appear to be highly susceptible to the aphids. Management recommendations: If the sooty mold can be tolerated, the crape myrtle aphid can be helpful in attracting Crape Myrtle Aphid many beneficial Biological Control 1
insects to the landscape. Insecticidal soaps, oils, or approved insecticides may be used to control aphid populations if necessary. Metallic beetles Recognition: Small blue metallic beetles feed on leaf surfaces and edges. Contributing factors: none Metallic beetle damage Management recommendations: Damage is usually insignificant. Control is difficult due to the mobility of the insect. Metallic beetle Powdery mildew (Oidium sp./erysiphe lagerstroemiae) Recognition: The fungus grows on the surface as a white powdery covering on leaves, shoots and buds. The disease causes leaf curling and growth distortion. Contributing factors: Powdery mildew is most active in the cool, dry periods of spring and fall. It is most severe in shady locations. Management recommendations: Resistant varieties are available. Use approved fungicides when conditions favor disease development. Culture There are 56 species of crape myrtle native to woodlands and forests of India, China and Southeast Asia. The commonly cultivated species are: Indica, Speciosa, Fauriei and 2
Hybrids. Some species are logged commercially for timber in India and Malaysia, but are threatened in Burma and Thailand from overlogging. Extracts from some species plant parts reportedly have medicinal uses; extracts from L. speciosa can be found in over-thecounter supplements The most widely grown species of crape myrtle, indica, was cultivated in ancient China and introduced to U.S. in the early 1800 s. Recently other species have been introduced for their own characteristics and for hybridizing with indica. Lagerstroemia indica has many ornamental qualities including: grows as multi-stemmed shrub or small tree, summer flowering, flower colors of purple, lavender, white, pink, and rose-red. It is easy to grow in full sun and well-drained soil; pest resistant; tolerant of drought, heat & humidity; tolerant of a wide range of soil ph; and easy to propagate by cuttings (softwood, semi-hardwood, hardwood and root). Unfortunately, Lagerstroemia indica has some limitations that gave breeders reasons to improve crape myrtle. It is susceptibility to powdery mildew, dead heading needed for best re-bloom, and the size availability was limited to large shrub or small tree. The introduction of new species and the hybridization of these has produced cultivars with increased disease resistance and variations in plant size and flower color among other characteristics. Recommended Cultivars Cultivars with unusual flower color Prairie Lace Candycane Raspberry Sundae Splash of Pink Petite Red Imp, Victor, Carolina Beauty, Dynamite Arapaho, Centennial Spirit, Christiana Houston, World s FairWatermelon Red Lipan Velma s Royal Delight Near East Muskogee, Basham s Party Pink Caddo Comanche, Tuscarora Firebird, Pink Velour pink edged in white pink edged in white dark pink edged in white mix of pink, white and bicolor flowers true red deep red watermelon red reddish lavender magenta purple shell pink lavender pink bubble-gum pink coral pink hot pink Dwarf Cultivars These cultivars are less than 4 feet tall in 5 years and can be used as: a small shrub/foundation plant, a groundcover (in masses), a woody/herbaceous perennial flower, a container plant, or a hanging basket. These cultivars and their flower colors include: Delta Blush pink New Orleans purple Pocomoke rose Houston rose pink 3
Semi-Dwarf Cultivars These cultivars are 4-12 feet tall in 10 years and can be used as a large shrub or limbed up to use as a patio tree or specimen plant. These cultivars and their flower colors include: Acoma white Caddo bubble-gum pink Hopi pink Tonto red Intermediate Cultivars These cultivars are 12-20 feet tall in 10 years and can be used as small trees or large shrubs. These cultivars and their flower colors include: Osage pink Dynamite true red Sioux pink Pink Velour burgundy foliage, hot pink flowers Apalachee lavender Tree Cultivars These cultivars grow over 20 feet tall in 10 years and can be used as small trees. These are many widely-available cultivars. Some of the new cultivars in this size category are: Biloxi light pink Choctaw pink Fantasy white; red bark Natchez white Sources 1. Knox, Gary W. 2003. (Extension pub.) ENH-52, Crape Myrtle in Florida 2. Neal, Cathy, Celeste White and Eleanor Foerste. Key Plant and Key Pests in Central Florida Landscapes. University of Florida Extension slide set. 3. University of Florida Landscape Plant Propagation Information. http://hort.ufl.edu/lppi/ 4. U.S. National Arboretum, www.usna.usda.gov/newintro/intro.html Prepared by: Juanita Popenoe, PhD, Lake County Extension, 1951 Woodlea Rd., Tavares, FL 32778 Tel.: (352) 343-4101, FAX: (352) 343-2767 July 2014 The Institute of Food and Agricultural Science (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. DEPARTMENT OF AGRICULTURE, COOPERATIVE EXTENSION SERVICE, UNIVERSITY OF FLORIDA, IFAS, FLORIDA A. & M. UNIVERSITY COOPERATIVE EXTENSION PROGRAM, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING. 4
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