| 
|
|
|
 |
|
St. Augustinegrass*,
Stenotaphrum secundatum (Walt.) Kuntze, had an early distribution in North
America, even though the other 6 species of the genus are historically strictly Old World
(Sauer, 1972). Its closest wild relative, pembagrass or S. dimidiatum
(L). Brongn., is sometimes used in east Africa for turf. Some writers have
considered St. Augustinegrass to have come from the West Indies. Nevertheless,
plants have not been seen from the West Indies like our naturalized Gulf Coast Group
(Busey et al., 1982), either living or as herbarium specimens. The type specimen of S.
secundatum was collected in the Carolinas in the late 1700's, which is consistent
with several alternative hypotheses regarding its introduction, or even native status, in
North America.
The earliest recorded use of St.
Augustinegrass as turf was in 1880, when it was planted along an avenue at A. M. Reed's
plantation near Orange Park, Florida (unpublished Diary of A. M. Reed, J. P. Waterbury,
personal communication). There were more frequent collections of St. Augustinegrass
in the 1880's and 1890's from Louisiana and Florida, including non-port areas (e.g.,
Florida central highlands). It is likely that during that era the species served as
forage. It grows in remote areas in Everglades National Park, e.g., Highland
Beach, 4 days by canoe from the nearest phone or fresh water (see photo; Busey,
unpublished observation). The area was inhabited briefly in the 1890's by people
with cattle.
Before 1920 there were St.
Augustinegrass lawns in Davie, Florida and sod trucks were observed in Miami (R. R.
Hammer, personal communication). The common St. Augustinegrass of that era was not
marked by a particular name. Based on plants maintained in breeding collections, a
survey of existing lawns (Busey, 1986), and a study of herbarium specimens (Busey,
unpublished) there were at least two "common" types. 'Florida Common' had
long, purplish internodes on the stolons and purple stigmas, whereas 'Texas Common' of the
Gulf Coast Group had green internodes and white stigmas. St. Augustinegrass sod
production in Florida was a matter of stripping out pastures so there was initially little
incentive to plant improved cultivars.
In the mid 1930's, several sod growers
(White & Busey, 1987) introduced the 'Bitterblue' cultivar. Although incorrectly
believed to be resistant to the southern chinch bug, Blissus insularis
Barber, Bitterblue was superior to Florida Common in other respects. Bitterblue had
a deeper blue-green blade color, denser growth, and shorter height. Bitterblue is
very susceptible to gray leaf spot disease caused by Pyricularia grisea
(Cke.) Sacc. (Atilano and Busey, 1983), which is still a problem in the production of that
cultivar. A pasture grass, 'Roselawn', was distributed in 1942 and 1943 by
Everglades Experiment Station, University of Florida (Allen and Kidder, 1971). After
much Bitterblue was destroyed in Davie, by the hurricane of 1947, ranchers around Lake
Okeechobee began to cut Roselawn pastures and sell the product as sod. As with
'Florida Common', 'Roselawn' has an open habit of growth, is light colored, and does not
form a dense sod.
Concerns about variety purity led the
University of Florida to release a Bitterblue-like plant, which was called 'Floratine'
(Nutter and Allen, 1960). Meanwhile, Florida sod producers had a state-sponsored
certification program implemented. Quality assurance was helpful in marketing, by
providing the consumer a dependable product. It also protected against the spread of
pest organisms. In all warm-season turfgrasses there are unresolved questions of
cultivar identity, and assurance of cultivar purity is essential for successful breeding
development and cultivar adoption to occur.
In 1973, The University of Florida and
Texas A & M University released 'Floratam' (Horn et al., 1973), which is resistant to
the southern chinch bug (Reinert and Dudeck, 1974) and to St. Augustine Decline Strain of
Panicum Mosaic Virus (PMV-SAD). The Floratam cultivar spread and became so popular
that by 1980-81 it dominated 77% of commercial sod sampled in southeast Florida, and had
penetrated 21% of lawn areas (Busey, 1986).
All the PMV-SAD resistant genotypes,
with one exception, are clones with purple stigmas and purple stolons (Bruton et al.,
1983). Likewise, only polyploid St. Augustinegrasses have antibiotic resistance to
the southern chinch bug (Reinert et al., 1986), although in some cases the southern chinch
bug has adapted to reproduce on and kill Floratam (Busey and Center, 1987).
O. M. Scotts and Sons contributed
significantly towards the development of dwarf St. Augustinegrass cultivars.
Breeding work by T. P. Riordan et al. (1980) resulted in the development of 'Seville' (=
S-6-68-516; Plant Patent 4097) and other strains which are under commercial development
('Delmar' = S-6-72-99 and 'Jade' = S-6-72-182). As a group these plants are more
susceptible to drought and to the southern chinch bug than Floratam. They are also
more shade tolerant, lower growing, and more esthetically acceptable to most observers
than Floratam.
Seedhead production is a major problem
of some diploid (2n = 18) St. Augustinegrasses, and this can markedly reduce the
appearance value of otherwise acceptable Seville, particularly during warm summer months.
Yet there is one strain, Plant Patent 3834 by C. L. Garrett, which has been
developed as a seed propagated type. Seedhead production in St. Augustinegrass is
under photoperiod control, but some there are genotypic differences in the dependence on
this stimulus (Dudeck, 1974).
Severe winter-kill occurs to St.
Augustinegrass following temperatures of -5 to -10 degrees Centigrade, although in a cold
resistance study in Mississippi, temperatures as low as -15 degrees Centigrade were
experienced (Wilson et al., 1977). Floratam has no survival from such cold
temperatures, whereas 'Raleigh' has 100% survival. Raleigh, developed by W. B.
Gilbert, North Carolina State University, was released for "commercial trial" in
1980. Another advantage of Raleigh is its resistance to PMV-SAD (Reinert et al.,
1980). This was an exception to the association of purple stigmas with PMV-SAD
resistance, since Raleigh has white stigmas (Busey et al., 1986). St. Augustinegrass
cold damage is related to management, e.g., excessive nitrogen fertilization (12 g N m-2)
applied in November and December (Reeves and McBee, 1972), but the genotype factor
is also great. Sod producers in Texas and northern Florida experienced considerable
loss of stand in Floratam due to cold weather, and converted many areas to Raleigh and
Texas Common, which was also relatively cold hardy. Both Texas Common and Raleigh
are in the Gulf Coast Group, which is apparently endemic to the United States (Busey et
al., 1986).
Mutation breeding was shown to create
favorable variations of St. Augustinegrass (Busey, 1980; Powell and Toler, 1980) while
preserving resistance characteristics (Reinert et al., 1981). No cultivars have
resulted from this work in St. Augustinegrass.
Inconclusive results have been
obtained from attempts to measure shade tolerance in St. Augustinegrass (Peacock and
Dudeck, 1981; Winstead and Ward, 1974), although Floratam has been shown to be quite
intolerant of shade (Barrios et al., 1986). The general progress of understanding
mechanism of environmental adaptation in St. Augustinegrass has been slow, but practical
results (e.g., shade tolerance in the Scotts germplasm, and cold tolerance in the Gulf
Coast Group) have been encouraging. These associations, along with similar racial
and/or ploidy generalizations for gray leaf spot disease (Atilano and Busey, 1983),
lepidopteran larvae damage (Busey et al., 1986), and chinch bug resistance (Reinert et
al., 1986), support the idea that "classification should serve as a prospectus of
beneficial genes" (Busey et al., 1986). Certain polyploid introductions from
Africa have the ability to survive greatly extended dry periods (months) of no irrigation,
provided relatively shallow (1.4 m) groundwater is present (Busey, 1996). For
coastal areas where St. Augustinegrass is commonly used, such a germplasm may have
tremendous value.
References
Allen, R. J., Jr., and R. W. Kidder. 1971. Origin and history of
Roselawn St. Augustinegrass. Proc. Soil and Crop Sci. Soc. Florida 30:354-360.
Atilano, R. A. and P. Busey. 1983. Susceptibility of St. Augustinegrass germplasm to
Pyricularia grisea. Plant Dis. 67:782-785
Barrios, E. P., F. J. Sundstrom, D. Babcock, and L. Leger. 1986. Quality and yield
response of four warm-season lawngrasses to shade conditions. Agron. J. 78:270-273.
Bruton, B. D., R. W. Toler, and J. A. Reinert. 1983. Combined resistance in St.
Augustinegrass to the southern chinch bug and the St. Augustine decline strain of panicum
mosaic virus. Plant Dis. 67:171-172.
Busey, P. 1980. Gamma ray dosage and mutation breeding in St. Augustinegrass. Crop Sci.
20:181-184.
Busey, P. 1986. Morphological
identification of St. Augustinegrass cultivars. Crop Sci. 26:28-32.
Busey,
P. 1996. Wilt avoidance in St. Augustinegrass germplasm. HortScience 31:1135-1138.
Busey, P., T. K. Broschat, and B. J. Center. 1982. Classification of St. Augustinegrass.
Crop Sci. 22:469-472.
Busey, P. and B. J. Center. 1987.
Southern chinch bug (Hemiptera:Heteroptera:Lygaeidae) overcomes resistance in St.
Augustinegrass. J. Econ. Entomol. 80:608-611.
Dudeck, A. E. 1974. Flowering response of several selections of St. Augustinegrass. p.
74-78. In E. C. Roberts (ed.) Proc. Second Int. Turfgrass Res. Conf., Blacksburg, VA.
19-21 June 1973. ASA and CSSA, Madison, WI.
Horn, G. C., A. E. Dudeck, and R. W. Toler. 1973. 'Floratam' St. Augustinegrass: A fast
growing new variety for ornamental turf resistant to St. Augustine decline and chinch
bugs. Fla. Agr. Exp. Stn. Circ. S-224.
Nutter, G. C. and R. J. Allen, Jr. 1960. Floratine St. Augustinegrass: A new variety for
ornamental turf. Fla. Agr. Exp. Stn. Circ S-123.
Peacock, C. H. and A. E. Dudeck. 1981. The effects of shade on morphological and
physiological parameters of St. Augustinegrass cultivars. p. 493-500. In R. W. Sheard
(ed.) Proc. Fourth Int. Turfgrass Res. Conf., Guelph, Ontario, Canada. 19-23 July 1981.
Ontario Agric. Col., Univ. Guelph and Int. Turfgrass Soc., Guelph, Ontario.
Powell, J. B. and R. W. Toler. 1980. Induced mutations of 'Floratam' St. Augustinegrass.
Crop Sci. 20:644-646.
Reeves, S. A., Jr., and G. G. McBee. 1972. Nutritional influences on cold hardiness of St.
Augustinegrass (Stenotaphrum secundatum). Agron. J. 64:447-450.
Reinert, J. A., B. D. Bruton, and R. W. Toler. 1980. Resistance of St. Augustinegrass to
southern chinch bug and St. Augustine Decline Strain of Panicum Mosaic Virus. J. Econ.
Entomol. 73:602-604.
Reinert, J. A., P. Busey, and F. G. Bilz. 1986. Old world St. Augustinegrasses resistant
to the southern chinch bug (Heteroptera:Lygaeidae). J. Econ. Entomol. 79:1073-1075.
Reinert, J. A. and A. E. Dudeck. 1974. Southern chinch bug resistance in St.
Augustinegrass. J. Econ. Entomol. 67:275-277.
Reinert, J. A., R. W. Toler, B. D. Bruton, and P. Busey. 1981. Retention of resistance by
mutants of 'Floratam' St. Augustinegrass to the southern chinch bug and St. Augustine
Decline. Crop Sci. 21:464-466.
Riordan, T. P., V. D. Meier, J. A. Long, and J. T. Gruis. 1980. Registration of Seville
St. Augustinegrass. Crop Sci. 20:824-825.
Sauer, J. D. 1972. Revision of Stenotaphrum (Gramineae:Paniceae) with attention to its
historical geography. Brittonia 24:202-222.
Wilson, C. A., J. A. Reinert, and A. E. Dudeck. 1977. Winter survival of St. Augustine
grasses in North Mississippi. S. Nurserymen's Assoc. Res. Conf. Ann. Rep. 22:195-198.
Winstead, C. W. and C. Y. Ward. 1974. Persistence of southern turfgrasses in shade
environment. p. 221-230. In E. C. Roberts (ed.) Proc. Second Int. Turfgrass Res. Conf.,
Blacksburg, VA. 19-21 June 1973. ASA and CSSA, Madison, WI.
Return to top
|
|
