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Beginning with funding from the USGA in 1993, a dedicated effort was
initiated to genetically enhance seashore paspalum for golf course use.
The grass has been around for centuries, actually evolving on sand dunes
exposed only to ocean water in South Africa. It’s somewhat ironic that
this grass evolved in the same country as the African bermudagrass, but
was never recognized for anything other than its ability to grow in salt-affected
environments. Seashore paspalum was duly noted as surviving the saline
and moist habitats that dooms most bermudgrasses.
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Fairbanks Ranch CC in Rancho Santa Fe, Calif., is helping to
pioneer seashore paspalum research. |
Legendary turf professor O.J. Noer was instrumental during the 1950s
for moving the grass around the southeastern United States and Hawaii.
A renewed effort occurred during the 1970s and 1980s with the import of
cultivars from Australia. Worldwide movement of this grass has been documented
(Duncan and Carrow, 2000).
Beginning in 1993, a systematic breeding and management research program
was started at the University of Georgia-Griffin to fully exploit the
potential recreational use of this species for golf courses on salt-affected
sites where other warm-season grasses have failed. It can also be used
in places with alternative non-potable water resources, including effluent
and brackish sources. Because of these stress challenges and increasing
need for water conservation and environmental stewardship, simply releasing
new cultivars was not sufficient. A parallel management protocol program
was instituted.
The research
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| Fairbanks Ranch CC in Rancho Santa Fe, Calif. |
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Initial breeding efforts at the University of Georgia started at the
same point at which most breeding programs involving a “new” grass do
— assembling a collection of ecotypes from around the world, followed
by implementation of an evaluation program to assess the turf traits and
the true genetic potential of the species.
At the same time, mother nurseries were established in Griffin, Ga.,
to start looking at the ecotypes in turf-plot situations. We exposed the
plots to rotary mowers and eventually reel mowers when the plot sizes
increased to simulate green, tee, fairway, landscape or sports field conditions
to determine mowing tolerance and to eliminate ecotypes that produced
unsightly seedheads. Drought-, acid-soil-, and salinity-tolerance studies
were initiated, as well as wear and traffic studies to assess the individual
ecotype levels of multiple-stress resistances.
 DNA
analysis studies were implemented to build a true genetic databank on
the new ecotypes as compared to the old cultivars. Insect studies were
initiated in concert with entomologists to determine the level of resistance
to fall armyworms, spittlebugs, mole crickets and white grubs.
A parallel management-oriented program was instigated at the same time
as the breeding and evaluation program. The initial mowing height studies
included taking the heights down to one-eighth inch to find green types
and to identify ecotypes that should only be mowed at fairway or rough
heights. Derivatives of the old cultivars were noted for their inability
to be mowed cleanly during the hottest times of the growing season and
were subsequently eliminated from the program.
Establishment studies identified those types that could root and grow
rapidly. Herbicide efficacy studies were instrumental in identifying the
tolerance or sensitivity of each ecotype to various herbicides. Encroachment
studies looked at bermudagrass movement into paspalum and paspalum movement
into bermudagrass.
New experimental herbicides were tried against the cultivars. Cold-hardiness
studies were used to determine the northern-most region of survivability
for the specific ecotypes.
All of these preliminary trial results were used to find the one or
two ecotypes with the best combination of turf traits that could be increased
in volume vegetatively, since this species is planted by sprigs or sod.
The promising ecotypes were sent to golf courses for the “final exam”
to determine their performance in end-use, real-world situations. The
result from all of this testing was the emergence of SeaIsle 1 (for fairways,
roughs, tees, landscapes, sports turf) and SeaIsle 2000 (for greens and
tees), with formal release by the University of Georgia in 1999.
Attributes
Great diversity exists among seashore paspalum ecotypes for all turf
characteristics. Choice of cultivars with university-researched attributes
is essential. SeaIsle 1 and SeaIsle 2000 exhibit the following attributes
when compared with other grasses:
- Highest salinity tolerance of all warm-season grasses — the best cultivars
are true halophytes.
- Can withstand most alternative water resources with varying levels
of salinity, including effluent, brackish and, in extreme cases, short-term
use of ocean water with proper management.
- Superior low-light intensity tolerance involving prolonged cloudy,
rainy, foggy or smoggy conditions.
- Forms both rhizomes and stolons, and readily responds to verticutting,
grooming or slicing.
- Wide soil pH range of 3.6 to 10.2, but the optimum range for maximum
performance is 5.5 to 8.
- Excellent drought tolerance when managed properly. The root system
must be trained deep into the profile with judicious irrigation scheduling.
- Wear and traffic tolerance similar to the bermudagrasses.
- Low-mowing height tolerance, with optimum ranges of one-eighth inch
for SeaIsle 2000 and .25 inches to .75-inches for SeaIsle 1. Roughs
mowed above 2 inches are definite penalty roughs. Landscapes can be
managed in the 1-inch to 2-inch range.
- Can be overseeded with most cool-season grasses, but the dense canopy
warrants use of a verticutter to ensure good seed-soil contact for the
cool-season grass.
- Capability to root and persist equally well in pure sands, heavy
clays and mucks or bogs.
- Can effectively and efficiently take up heavy metals or other contaminants.
- Excellent waterlogging or low oxygen tolerance. Can be inundated
for short intervals with minimal detrimental effects.
- Capable of providing an effective buffer zone between environmentally
sensitive areas and less sensitive areas (fairways or roughs transitioning
into wetland areas and sand-dune stabilization).
- Chilling tolerance that provides prolonged color retention into the
fall or winter months. Normally the last warm-season grass to go off
color. SeaIsle 2000 actually has the best winter-hardiness.
- Seedheads for monostands of a cultivar do not readily produce viable
seed. SeaIsle 2000 produces minimal seedheads during the growing season.
- Does not form a grain; holds the striping pattern exceptionally well.
- Looks like Kentucky bluegrass or perennial ryegrass — shiny, glassy
dark green hue.
- Has a nutrient uptake and use system that is quite efficient.
Limitations
Every turfgrass has pluses and minuses, and seashore paspalum is no
different. Some of the limitations include:
- Minimal shade tolerance, with similar responses to bermudagrass under
tree canopies. It needs about six to eight hours of sunlight daily for
good performance.
- Cold-hardiness similar to most of the hybrid bermudagrasses and actual
adaptation to the southern transition zone in the United States.
- Cannot be effectively and rapidly established with irrigation water
high in salinity (more than 5,000 parts per million of total salts)
due to suppression of growth. Juvenile roots of all turfgrasses are
sensitive to salt levels in the irrigation water, and paspalum is no
different. Salinity tolerance of mature turf is substantially higher
than immature turf.
- Few pesticides are specifically labeled for seashore paspalum.
- Seedheads may persist with some other cultivars that are on the market
during certain months of the growing season.
- Lack of understanding the interactions among paspalum cultivars, salinity
in the irrigation water, soil buildup of salts and the microenvironments
on the golf course or on other sites, which necessitates specific changes
in paspalum management to maximize long-term performance.
- Doesn’t like to be scalped. Excess nitrogen can lead to succulence
and enhanced scalping, thereby predisposing the grass to pathogen attack.
Future research and educational activities
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Kapolei GC in Oahu, Hawaii, benefited from greens-grade
seashore paspalum. |
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A refinement of the management practices for greens is receiving top
priority. Additional greens-type cultivars have been identified and are
being increasingly produced for on-course evaluations.
A seeded hybrid cultivar is in preliminary production and evaluation
and may be on the market in three to five years. The breeding is always
focused on the development of new and improved cultivars, with promising
experimentals having ocean-level salinity tolerance and improved multiple
insect resistance.
A lawn/landscape cultivar has been identified and is being evaluated
in Florida. A nematode assessment is being collaboratively investigated
in South Carolina and Florida. The potential for enhancement of low-light
intensity tolerance and subsequent management are under investigation,
along with studies on irrigation scheduling and water uptake/use efficiency
for paspalum.
This grass is an environmentally friendly grass with multiple uses and
multiple stress tolerances. As the grass increases in acreage in end-use
situations and is exposed to the challenges of Mother Nature, more information
will be gleaned and translated into a refinement of management protocols
for specific stress environments.
Ronny R. Duncan and R.N. Carrow are professors in turfgrass breeding
and stress physiology in the University
of Georgia’s department of crop and soil sciences at the University’s
Griffin campus. Duncan has been working with developing grasses for
multiple stress environments, including drought, acid soils, high and
low temperatures, high-bulk density soils and salinity stresses. Carrow
has spent his entire career in turfgrass research, with expertise in environmental
and traffic stresses. They can be reached at rduncan@gaes.griffin.peachnet.edu
and at rcarrow@gaes.griffin.peachnet.edu,
respectively.
For more information on this cultivar, see the authors'
Seashore paspalum page.
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