CtQ '[AREC-Monticello Research Report BB 90-1 Central0 '
LAGERSTROEMIA CULTIVARS UNDER EVALUATION Library f
AT THE UNIVERSITY OF FLORIDA/IFAS
AGRICULTURAL RESEARCH AND EDUCATION CENTER MONTIdYL ti
Gary W. Knox and Jeffrey G. Norcini UliVrs ;t Of
Route 4, Box 4092
Monticello, Florida 32344-9302
Many new cultivars of Lacerstroemia spp. have been released
in the past few years. Homeowners, landscapers, and nursery
growers are now faced with a large number of crape myrtle
cultivars from which to choose. To our knowledge, most of these
cultivars are not being publicly evaluated in USDA Zones 8 or 9.
Thanks to the generosity of local and regional nurseries, the
AREC-Monticello has initiated a planting of Lagerstroemia
cultivars that will allow us to evaluate new cultivars and
compare them to older cultivars for their adaptability to the
north Florida south Georgia area.
Table 1 lists the 35 cultivars of crape myrtle
(Lagerstroemia species) that are planted on 2 sites at the AREC-
Monticello. Four plants of each cultivar (except those
indicated) have been planted over the past 2 years (2 plants of
each cultivar on each site). Initial size of the plants ranged
from 1-gallon containers to 6-foot-tall bare-root plants.
The plantings feature many of the cultivars released by Dr.
Donald Egolf of the National Arboretum in Washington, D.C. These
cultivars have been specially selected for their ornamental
characteristics such as autumn color, bark characteristics, and
plant habit, as well as flower color. Many of these cultivars
also are noted for their resistance to powdery mildew.
We also have plants from the "Dixie" series of cultivars
developed by David Chopin of Louisiana. The "Dixie" cultivars
reportedly grow less than 5 feet tall and are promoted for use as
small shrubs or groundcovers.
The cultivars in our plantings are grouped by mature size as
classified by Egolf and Andrick (The Lagerstroemia Handbook/
Checklist, 1978): dwarf = less than 3 feet; semi-dwarf = 3 to 6
feet; medium = 6 to 12 feet; and, tall = 12 feet or more. Plants
are grouped in rows spaced 20 feet apart except for dwarf
cultivars which are 5 feet apart. Individuals are spaced within
rows according to their size classification: dwarf plants are 8
feet apart, semi-dwarf plants are 10 feet apart, medium plants
are 15 feet apart, and tall plants are 20 feet apart.
The plantings are intended to simulate a low-maintenance
landscape. Plants are not irrigated but are mulched with 3 to 4
inches of coarse pine bark. The plantings receive minimal
fertilization of 2 lbs. nitrogen/1000 ft2 per year. Pesticides
are applied as needed and, in 1989, pest control consisted of 1
application of Bacillus thuringiensis on August 17 to control
caterpillars and 1 application of an insecticidal soap on
September 10 to control aphids.
Plant height and spread are recorded monthly during the
growing season, and aphid and powdery mildew infestations are
evaluated periodically. Other characteristics that are being
recorded include date of first flower, length of flowering
season, autumn color, time of leaf drop, and bark
S characteristics. Beginning next year, we hope to issue annual
reports on the growth and ornamental characteristics of these
Table 1. Cultivars of Lagerstroemia spp. being evaluated at the
CULTIVAR SIZE GROUP1
Baton Rouge D
Bayou Marie D
Bourbon Street D
Byers Wonderful White n.a.
Carolina Beauty M
Cordon Bleu D
Country Red2 T
Dallas Red T
Delta Blush D
Near East M
New Orleans D
Regal Red T
1 D dwarf; S-D semi-dwarf; M medium; T tall; n.a. not
2 Less than 4 plants are being evaluated.