Plant Growth Regulators' Effect on Growth of
Mixed Cool-Season Grass Stands at Fort Drum
ANTONIO J. PALAZZO, PAUL ZANG, ROBERT W. DUELL,
TIMOTHY J. CARY AND SUSAN E. HARDY
mal seedhead control; it should be applied at least
INTRODUCTION
14 days before seedhead emergence. Turf injury
Turfgrasses that provide a suitable vegetative
is a factor to be considered when using PGRs.
cover for parade grounds, roadsides, and hous-
Some stand density losses have been observed
ing areas are widely used in cantonment areas at
(Wakefield and Fales 1977) and visual injury is
military facilities. In the training areas, grasses
more pronounced when the grass is environmen-
are a cost-effective means of controlling erosion
tally stressed (Duell et al. 1977), but these factors
on the gunnery ranges. In all these areas, the
are less important in low-maintenance turf situa-
grasses must be mowed to maintain the required
tions. The effectiveness of PGRs in reducing
visibility or appearance of a mowed turf. Fort
turfgrass growth has been reported to be substan-
Drum is currently mowing approximately 2,025
tially reduced during years of low rainfall
ha (5,000 acres) of turf in the cantonment area and
(Reynolds et al. 1993).
several hundred acres at the gunnery ranges.
Mefluidide retards plant growth through the
Grasses are usually mown to reduce leaf height
inhibition of cell division and meristematic activ-
or to remove seedheads.
ity in the responsive plant areas where the com-
The cost of mowing these lands is expensive in
pound is absorbed. Mefluidide is absorbed by the
labor and equipment and may add up to several
leaf and exhibits little translocation to other leaf
hundred dollars per acre annually. Innovative
organs, roots, and lateral growth meristems (Field
techniques are required to reduce mowing costs,
and Witford 1982, WSSA 1983). Penetration of
control erosion, and maintain the aesthetics of
leaf tissue occurs most readily at basal leaf sheaths
turf areas, allowing the labor and money saved to
and leaf axils, where cell division and elongation
be used for special projects or other maintenance
occur, causing reduced sheath extension and
functions. Plant growth regulators (PGRs) have
canopy height. Uptake is complete in 4 to 6 hours
the potential to reduce mowing costs.
after application (Tautvydas 1983). Mefluidide also
The PGR "Embark" contains mefluidide {N-
causes uncontrolled cell division in reproductive
[2,4-dimethyl-5-[[(trifluoromethyl)-sulfonyl]
apices, distorting stem extension and impairing
amino] phenyl] acetamide}, which was commer-
seedhead development (Field and Witford 1982).
cially introduced in 1978 as a seedhead and foliar
Because of limited movement within the plant,
suppressant for use in rough turf areas (Elkins
uniform spray coverage and distribution is essen-
1983, Johnston and Faulkner 1985). Watschke et
tial (Watschke et al. 1992).
al. (1992) provided an excellent review on meth-
The PGR "Event" contains imidazolinone [5-
ods of application and the functions of mefluidide
ethyl-2- (4-isopropyl-4-methyl-5-oxo-2-imidazo-
within plants. Field and Witford (1982) reported
lin-2-yl) nictotinic acid]. This compound has an
that applications of mefluidide should be limited
extremely high margin of safety (Watschke et al.
to green and actively growing grass. For leaf
1992). It has post-emergence herbicide activity on
growth regulation, mowing the sward 4 to 5 days
many annual and perennial grasses. Watschke et
before or after the application will provide a
al. (1992), in their review of PGRs, reported that
sustained mowed appearance. The timing of
some studies with this PGR have shown the com-
mefluidide applications is more critical for opti-
pound to suppress foliar growth and seedhead
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