Here's some good information from two professors in Louisiana.
'Top Eight' Crape Myrtle Cultivars
By Allen D. Owings, Associate Specialist (Horticulture)
and Gordon E. Holcomb, Professor (Plant Pathology),
Louisiana State University, Baton Rouge
Crape myrtles (Lagerstroemia indica, Lagerstroemia indica x faurei) continue to be one of the most widely used landscape trees in the southeastern United States. Over the last several years, the Louisiana State University Agricultural Center has evaluated numerous cultivars for susceptibility/tolerance to powdery mildew and Cercospora leaf spot, two of the most prevalent diseases of crape myrtles in Louisiana and Texas. Flower performance and growth habit also have been observed. The following is a list of the â€œtop eightâ€ crape myrtles for Texas and Louisiana, as recommended by the Louisiana Cooperative Extension Service:
Natchez is recognized as the top performing crape myrtle in the southeastern United States. It was introduced by the U. S. National Arboretum in 1987. White flowers and exfoliating bark are characteristic of this cultivar, which reaches heights of 30 feet at maturity. Bloom period is about 110 days in Louisiana, starting in early June. Very large blooms.
Muskogee was introduced in 1978, and has medium-size, light lavender flowers. Blooming period is excellent, beginning in mid-June, and lasting 110 to 120 days. Some years, flowers are as early as late May in Baton Rouge. Good tolerance to powdery mildew and leaf spot. Exfoliating bark is grey-tan to medium brown. Bark characteristics are desirable, but not as good as Natchez and Tuscarora. Reaches a mature height of over 20 feet.
This cultivar was introduced in 1981, and is characterized by coral pink flowers. It is less susceptible to powdery mildew and leaf spot than most cultivars. Flowering begins in late June or early July, and will continue for 70 to 80 days. The trunk has mottled, light-brown bark that exfoliates increasingly as the tree ages. This cultivar can easily reach heights of 25 feet in the landscape, and has performed well in landscape plantings across Louisiana.
Tonto is a semi-dwarf to medium crape myrtle, reaching heights of 12 to 14 feet. It was released by the U. S. National Arboretum in 1990, and has been recognized as a Georgia Gold Medal winner (1996) and Mississippi Medallion plant (1999). Excellent resistance to leaf spot and powdery mildew. Good foliage retention into the fall months. Flowers are deep red. Satisfactory exfoliating bark.
Bashamâ€™s Party Pink
Bashamâ€™s Party Pink is a tall-growing hybrid cultivar introduced to the nursery trade by Texas nurseryman Lynn Lowery in 1965. Blooms are lavender-pink, and compete with Natchez for size. Very comparable and similar in performance to Muskogee. Good resistance to leaf spot and powdery mildew in LSU Agricultural Center evaluations. Cold hardiness is not as good as Muskogee.
Acoma was introduced by the U. S. National Arboretum, and reaches a height of 10 to 14 feet, similar in size to Tonto. Weeping/cascading type growth habit. White flowers appear in mid to late June, and last around 90 days. Powdery mildew resistance is good. Some years, leaf spot is observed on this cultivar; defoliation is not a problem.
Sioux has been recognized as a Georgia Gold Medal winner (1996) and Mississippi Medallion plant (1999). Good powdery mildew resistance in LSU Agricultural Center trials. Some susceptibility to leaf spot. Flowers are vivid pink, and last from June through September. Mature height ranges from 10 to 15 feet, but can be widely variable.
Tuskegee was introduced in 1986. Flowers are dark pink. Typical average height is 15 to 20 feet. Excellent resistance to powdery mildew and Cercospora leaf spot.