|dc.description.abstract||Most cultivars of crapemyrtle are vigorous growers under nursery conditions;
however, some cultivars begin flowering by early summer, resulting in suppressed
vegetative growth, particularly height growth, a problem often compounded by heavy
fruit set later in the growing season. Pruning of inflorescences is labor-intensive and
results in rapid re-bloom. For production of standard (single trunk) or multi-trunk
tree-forms of crapemyrtle with 112 cm to 183 cm of clear trunk, pruning exacerbates
the problem by stimulating new shoot formation, often from the main trunk.
The effects of production light level on growth of crapemyrtle were evaluated
as a means of accelerating the development of tree-form crapemyrtles. Plant height
of ‘Fantasy’, ‘Carolina Beauty’, and ‘Tuscarora’ was greater when grown under 50%
or 80% shade than when grown in full sun. Trunk diameter or caliper of Dynamite™
and ‘Tuscarora’ was greatest when grown in full sun, while production light level had
no effect on caliper of ‘Carolina Beauty’.
Dynamite™, ‘Muskogee’, ‘Natchez’, and ‘Tuscarora’ grown in Oregon were
taller than plants in Alabama, while plants generally had less caliper in Oregon.
‘Muskogee’ and ‘Natchez’ in both locations were generally taller when grown under
50% shade than plants in full sun. Caliper of ‘Natchez’ in both locations was less
when plants were grown under shade, while caliper of ‘Muskogee’ and ‘Tuscarora’
was not affected by production light level. Flowering of crapemyrtles grown under
shade in Alabama was delayed or suppressed in each experiment, while no plants in
Oregon flowered the first year of production.
In another study, the effects of production light level on coppicing and
coppice timing were evaluated as means of accelerating the development of tree-form
crapemyrtles. Coppiced plants were generally taller when grown under lower light
levels, while coppicing crapemyrtle while dormant resulted in greater height and stem
cross-sectional area than delaying until the growing season, with no effect on
survival. Visually, coppiced plants had more uniform shoot diameters and less
branching than non-coppiced plants.
Dynamite™ and ‘Potomac’ grown in tree shelters were taller at the end of two
experiments, while caliper was minimally affected. All plants grown in tree shelters
flowered later than unsheltered plants and appeared to have straighter, more upright
trunks with minimal lateral shoot development.||en_US