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Crapemyrtle Database
Introduction
The crapemyrtle (Lagerstroemia sp.), native to SE Asia, is a very popular woody
ornamental flowering shrub/small tree throughout southeastern US landscapes. The
fact that crapemyrtles have the potential for a long flowering period (up to 120
days) in the summer has given rise to the popularity of this plant. Today we are
fortunate to be able to pick from a wide variety of cultivars that offer us an
assortment of ornamental characteristics. Breeding programs in USA and Europe
have generated in the last three decades a wide range of plant sizes (from 2’
dwarfs to 30’ tall trees), growth habits (broad, upright, weeping, etc..),
cold hardiness (Zones 6-10), disease resistance (powdery mildew and leaf spot)
and a wide range of bark characteristics, flower color and
fall color. The
Arkansas Champion Tree, located in Pulaski County, is 43 feet tall and 47
feet in spread.
Out of all the Lagerstroemia species, L. indica is the most widely known and
cultivated. Breeding programs utilize other species including L. fauriei and
L. speciosa. The rather obscure and perhaps nearly extinct L. fauriei, found
only in the island of Yakushima, Japan has brought the most significant developments
in the breeding of modern ornamental Lagerstroemia cultivars, contributing mainly
with powdery mildew resistance, cold hardiness and attractive bark Many cultivars
have been introduced by the U.S. National Arboretum (http://www.usna.usda.gov/
) including: ‘Pocomoke’, ‘Acoma’, ‘Caddo’,
‘Hopi’, ‘Tonto’, ‘Cherokee’, ‘Osage’,
‘Sioux’, ‘Tuskegee’, ‘Tuscarora’, ‘Biloxi’,
‘Kiowa’, ‘Miami’, and ‘Natchez’. Introductions
by the University of Arkansas include: ‘Centennial’, ‘Hope’,
and ‘Victor’.
Pruning:
Dehorning (or topping) is, sadly, a widespread pruning practice applied to many crapemyrtles. Fortunately the plant can withstand such abuse. Proper selection
of the right cultivar (i.e. size and growth habit) should take priority over
improper pruning if this is justified by space considerations. Contrary to popular
beliefs, excessive pruning in crapemyrtles does not induce heavier flowering,
but rather detracts from it due to the likely removal of significant
plant carbon and nutrient (i.e. food) reserves.
Proper pruning of the shrub or tree types includes selectively removing branches
back to a branch (thinning). Crapemyrtle flowers on new stems/wood so plants
can be pruned until late spring without reducing flowering that summer.
Diseases:
There are two serious and common fungal diseases on crapemyrtle:
powdery mildew
(Erysiphe lagerstroemiae) and
Cercospora leaf spot. In Arkansas, the more serious
disease is leaf spot which can cause susceptible varieties to be nearly defoliated
by late August. While chemical controls could be used, we encourage planting
varieties that are less susceptible to both of these diseases. A good fact sheet
on the two diseases is available:
http://www.aces.edu/pubs/docs/A/ANR-1047/ANR-1047.pdf
Insects:
Although metallic green flea beetle (Altica sp.) is noted as a serious insect
pest in many southeastern states it does not appear to be a serious problem
on crapemyrtle in Arkansas yet.
Arkansas is fortunate to have two individuals that I credit with introducing
this fine plant to our state in the 70’s. Recognition needs to go to Ewa
and Joan Nelson of
Morningside Nursery in Morrilton
and Stan Brown of Blossomberry Nursery in Russellville.
Other information:
http://dallas.tamu.edu/woody/cmyrtle/
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