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Origin and Early History *
Bermudagrass (Cynodon spp.) was introduced to the United States from Africa by
1751 (Hanson, 1972a). The high growth rate of this genus (Busey and Myers, 1979)
provides it with rapid colonization in disturbed areas and quick recovery from traffic
damage caused in sports activities. It was shown that if logarithmic
growth rates could be sustained for 1 year (e.g., through ideal environment and
frequent division), then "it would be possible for 1 m2 of grass to cover
an area equal to 50% of the land area of the world" (Busey and Myers, 1979).
Carolina farmers of the 1700's
preferred it as a forage, calling it "crop grass or crab grass (Syntherisma)",
according to Drayton's View of South Carolina (Gray, 1958). Bermudagrass was planted
on golf courses (Carrier, 1927) and lawns (Enlow and Stokes, 1929) in Florida at least by
the 1920's. 'St. Lucie' was the first turf bermudagrass recognized in the U.S.
(Tracy, 1917). St. Lucie was a slender dwarf plant used in Florida lawns, but it was not
hardy as far north as middle Georgia. The fine-leaved texture of bermudagrass was
recognized as an advantage for use in lawns, but its intolerance to shade was also noted
(Enlow and Stokes, 1929). Arizona grown (probably common, C. dactylon) seed was
planted in most golf course fairways, greens, and tees in Florida in the 1920's (R. A.
Bair, personal communication).
Species and Cultivars
Eight species of Cynodon are recognized, of which turf types are included only
in the 2n = 36 C. dactylon (L.) Pers. var. dactylon ("common
bermudagrass"), the 2n = 18 C. transvaalensis Burtt-Davy ("African
bermudagrass"), and their 2n = 27 interspecific hybrid C. X magenissii
Hurcombe (= C. dactylon X C. transvaalensis) (Harlan et al.,
1970a). My interpretation of C. X magenissii being equivalent to C.
dactylon X C. transvaalensis, and reciprocals, has not been
recognized by taxonomists, but should be studied. This tri-partite interpretation of
turf species relationships in Cynodon is a simplified classification based on
incomplete knowledge. Extensive studies of genetic variation have emphasized wide
crosses (Harlan et al., 1969) and forage development, and very little documentation is
available regarding the taxonomy and relationships of cultivated turf types.
Cytological evidence suggests that C. transvaalensis could be considered a
botanical variety of C. dactylon, but that it is distinctive in geography,
ecology, and morphology (Harlan et al., 1970b). Taxonomy of bermudagrass is helpful in
understanding its breeding development.
Early selection work emphasized C.
dactylon. Probably much of the germplasm base for early selections was from
seeded plantings. At one time all the commercial seed used in the United States came from
Australia (Tracy, 1917). The first test plantings were reported to have been made
around 1918 at East Lake Country Club by C. V. Piper of the United States Golf Association
Green Section. Out of this came the 'Atlanta' strain about 1924 (Latham,
1966). Additional clones were selected by golf course superintendents in the United
States and the Republic of South Africa. There was little organized breeding. Important
cultivars included 'Ormond', by R. A. Bair, released in Florida in 1962; 'Royal Cape', by
C. M. Murray, Republic of South Africa, in 1930; and 'Tiflawn' (T-57), by G. W. Burton,
Georgia, distributed in 1952 (officially released 1956). Ormond and Tiflawn have had
a continuing success for use in recreational turf. Tiflawn tolerates heavy traffic,
requires little fertilization, is fast spreading, and is generally disease and insect
resistant (Hanson, 1972a). Ormond is blue-green, competitive, and performs
moderately well under conditions of natural pest infestation (Scapteriscus mole
crickets, especially) and suboptimal N fertilization (Busey, 1986).
The foregoing cultivars are sometimes
lumped together as common bermudagrass. The name "common bermudagrass" is
confusing and questionable. It refers in the U. S. to a landrace cultivar, which is
produced as seed in Arizona and other states, is widely recognized, but has not been
adequately described. When used as a collective term, "common" can also
refer to any C. dactylon. In some usages, "common" has become
synonymous with any seed propagated bermudagrass. Because of its coarse habit of growth,
there is relatively little interest in using plants of this group in the subtropics, where
some of the sterile hybrids (below) can be used. In temperate areas where cold can be a
problem, C. dactylon is better adapted than other Cynodon species, and there
has been a continuing effort to improve cold hardiness and turf characteristics. In 1930
A. B. Dorrance started to select bermudagrass for cold hardiness in Augusta, Michigan
(Hanson, 1972b). 'Midiron', developed by R. A. Keen, Kansas State University, shows
considerably less winter-kill than several other cultivars (Juska and Murray, 1974).
Burton (1974) produced hundreds of F1 hybrids involving a cold hardy Berlin collection.
The cultivar 'Vamont' was released from Virginia for its cold hardiness. Wofford and
Baltensperger (Wofford and Baltsenberger, 1985) performed extensive heritability tests for
turfgrass characteristics in C. dactylon.
Clones of the 2n=18 C. transvaalensis,
including 'Uganda', were introduced to the United States. They crossed with the
naturalized 2n=36 C. dactylon to produce sterile 2n=27 hybrids. The products
of these crosses became useful cultivars, such as 'Sunturf', 'Everglades-1', 'Gene Tift'
(='Bayshore'), and a long line of successful Tifton hybrids. In general turf usage,
"hybrid" bermudagrass has come to mean any interspecific hybrid involving C.
dactylon and C. transvaalensis. The first Tifton interspecific hybrid
was 'Tiffine'. Tiffine was a cross of C. transvaalensis X C. dactylon
(Forbes and Burton, 1963). It was too stemmy for use on putting greens (Latham, 1966).
A remarkably successful hybrid cultivar
'Tifgreen' (Tifton-328, C. dactylon X C. transvaalensis)
was officially released in 1956, and it made an excellent putting surface. It was followed
by 'Tifway' (Tifton-419, C. transvaalensis X C. dactylon
X ) in 1960. Tifway had a stiffer, more erect growth habit, and greater pest and wear
resistance than Tifgreen. In 1974 Tifgreen and Tifway represented 78% of the areas planted
to specific grasses on Florida golf course greens, tees, and fairways (Anonymous, 1976).
One must be cautious in accepting that estimate, which was based on interviews of
turfgrass managers, because I have observed that some areas of golf course fairways and
sod fields that are claimed to be Tifway are actually Ormond (Busey, personal
observation). The leaf blades of Tifway are pilose, with 10 or more hairs on both
surfaces, whereas those of Ormond are sparingly pilose (Thompson, 1965).
Clonal Variation
Clonal off-types were discovered in Tifgreen, and they were presumed to have
arisen as spontaneous mutations. Two off-types were selected as cultivars, 'Tifdwarf'
(USDA Coastal Plains Experiment Station, Tifton, Georgia, 1965) and 'Pee Dee 102' (South
Carolina Agricultural Experiment Station, 1968). Under close cutting Tifdwarf can provide
very rapid golf ball roll. The problem of vegetative sporting in "hybrid"
bermudagrass is widespread, but has not been adequately documented. Because of the rare
nature of mutation events, it is not likely that one could prove that mutations were
involved, to the exclusion of alternative hypotheses (e.g., contamination of breeding
stock). I have been shown several instances of off-types, which had been observed, during
the growing in of planting stock. This suggests that the immediate problem may be
contamination of planting stock, even though mutations ultimately may have been involved.
Maintenance of genetic purity is a
major problem for golf course superintendents, turfgrass producers, and plant breeders.
"Clonal degeneration" is not an isolated phenomenon in bermudagrass, but has
been noticed in potatoes and other crops, in which a "running out" may occur.
Several different phenomenon can occur, including the "risk of multiplying mutations
or cryptically diseased material" (Simmonds, 1972). Clonal selection also allows for
openings of genetic vulnerability, because of the fundamental genetic similarity of clonal
off-types.
Golf course superintendents have
continued to make new vegetative selections from the off-types that they find. This will
be a viable source of variability in quality characteristics. A synthetic approach to this
goal has been the use of non-ionizing radiation, e.g., gamma rays, to create artificial
mutations. Beginning in 1970 Powell et al. (Powell et al., 1974) irradiated thousands of
rhizomes of Tifton bermudagrass cultivars. Two clonal cultivars were released from this
work, 'Tifway-II' in 1981 (Burton, 1985) and 'Tifgreen-II' in 1983. Tissue culture
techniques may now be useful for increasing bermudagrass clonal variations, because plant
regeneration has been shown to occur from calli (Ahn, 1985).
Environmental Stresses
There is considerable undocumented field information on pest resistance of
bermudagrass cultivars, which has served as a basis for cultivar descriptions and
releases. The few published studies have been based on individual experiments involving a
small number of bermudagrasses grown in containers. Those experiments have not been
adequately correlated with field studies. One might speculate (Busey, 1986) that the
low-maintenance adaptation of Ormond and some plant introductions (e.g., PI-291586) is
related to pest resistance, i.e., Scapteriscus mole crickets (Reinert and Busey, 1984),
ectoparasitic nematodes (Tarjan and Busey, 1985), tropical sod webworm, Herpetogramma
phaeopteralis Guenee (Reinert and Busey, 1983), and bermudagrass mite, Eriophyes
cynodoniensis Sayed (Reinert et al., 1978). Unfortunately, it is difficult to
extrapolate to field level resistance without more information. For highly mobile grass
pests such as caterpillars (lepidopteran larvae), cafeteria style grazing trials (Leuck et
al., 1968; Reinert and Busey, 1984) are of undetermined value. Insects in the field are
generally confronted with turfgrass monocultures, and the element of nonpreference which
is noticeable in controlled screening trials would be of little or no impact in the field,
unless it is correlated with other resistance mechanisms.
Physiological studies were done to
select for better adaptive range for bermudagrass. 'No-Mow' (FB-137) bermudagrass is more
tolerant to shade than 'Tifway', based on color and ground cover ratings when both grasses
are grown at 35% and 25% incident light (McBee and Hold, 1966). 'Brookings' bermudagrass
has significantly higher regrowth than seven other cultivars, when all are subjected to -4
to -11 degrees Centigrade soil temperatures (Ibitayo et al., 1981). Electrolyte loss curve
data suggested that the low temperature kill point of hardened material ranges from -7 to
-17 degrees Centigrade, depending on the bermudagrass cultivar. Salt tolerance differences
exist among bermudagrasses (Dudeck et al., 1983), with Tifdwarf showing maximum root
growth at moderately high (20.5 dS m-1) electrical conductivity (EC), or about
47% the concentration of seawater. Other cultivars show maximum root growth at lower EC
values. One of the advantages of bermudagrass is its high N responsiveness, which provides
a recuperative ability against wear and herbivory. Yet some work has been done in Florida,
New Mexico, and other locations, to select for adapted, low-fertility requiring
bermudagrasses. Differences in air pollution (ozone and peroxyacetyl nitrate) tolerance
exist among bermudagrasses, with Tifgreen being intermediate in response, while Santa Ana
and Common are not injured (Youngner and Nudge, 1980).
References
Ahn, B. J., F. H. Huang, and J. W. King. 1985. Plant regeneration through
somatic embryogenesis in common bermudagrass tissue culture. Crop Sci. 25:1107-1109.
Anonymous. 1976. Florida turfgrass survey 1974. Florida Department of Agriculture and
Consumer Services, Tallahassee, FL.
Burton, G. W. 1974. Breeding bermudagrass for turf. p. 18-22. In E. C. Roberts (ed.) Proc.
Second Int. Turfgrass Res Conf., Blacksburg, VA. 19-21 June 1973. ASA and CSSA, Madison,
WI.
Busey, P. 1986. Bermudagrass
germplasm adaptation to natural pest infestation and suboptimal nitrogen fertilization. J.
Am. Soc. Hort. Sci. 111:630-634.
Busey, P. and B. J. Myers. 1979.
Growth rates of turfgrass propagated vegetatively. Agron. J. 71:817-821.
Carrier, L. 1927. Florida greenkeeping. Natl. Greenkeeper, Oct. 1927. p. 20 and 25.
Dudeck, A. E., S. Singh, C. E. Giordano, T. A. Nell, and D. B. McConnell. 1983. Effects of
sodium chloride on Cynodon turfgrasses. Agron. J. 75:927-930.
Enlow, C. R. and W. E. Stokes. 1929. Lawns in Florida. Florida Agr. Exp. Stn. Bul. 209.
Forbes, I., Jr., and G. W. Burton. 1963. Chromosome numbers and meiosis in some Cynodon
species and hybrids. Crop Sci. 3:75-79.
Gray, L. C. 1958. History of agriculture in the southern United States to 1860. Peter
Smith, Gloucester, Mass. Reprinted as Publ. 430 by the Carnegie Institution of Washington.
Hanson, A. A. 1972a. Breeding of grasses. p. 36-52. In V. B. Youngner and C. M. McKell
(eds.) The biology and utilization of grasses. Academic Press, New York.
Hanson, A. A. 1972b. Grass varieties in the United States. USDA Agr. Hdbk. 170.
Harlan, J. R. and J. M. J. de Wet. 1969. Sources of variation in Cynodon dactylon (L.)
Pers. Crop Sci. 9:774-778.
Harlan, J. R., J. M. J. de Wet, W. W. Huffine, and J. R. Deakin. 1970a. A guide to the
species of Cynodon (Gramineae). Oklahoma State Univ. Bull. B-673.
Harlan, J. R., J. M. J. de Wet, K. M. Rawal, M. R. Felder, and W. L. Richardson. 1970b.
Cytogenetic studies in Cynodon L. C. Rich. (Gramineae). Crop Sci. 10:288-291.
Ibitayo, O. O., J. D. Butler, and M. J. Burke. 1981. Cold hardiness of bermudagrass and
Paspalum vaginatum Sw. HortScience 16:683-684.
Juska, F. V. and J. J. Murray. 1974. Performance of bermudagrasses in the transition zone
as affected by potassium and nitrogen. p. 149-154. In E. C. Roberts (ed.) Proc. Second
Int. Turfgrass Res. Conf., Blacksburg, VA. 19-21 June 1973. ASA and CSSA, Madison, WI.
Latham, J. M., Jr. 1966. Better bermudagrass greens and tees. Milwaukee Sewerage
Commission Bull no. 6, Milwaukee, WI.
Leuck, D. B., C. M. Taliaferro, G. W. Burton, R. L. Burton, and M. C. Bowman. 1968.
Resistance in bermudagrass to the fall armyworm. J. Econ. Entomol. 61:1321-1322.
McBee, G. G. and E. C. Holt. 1966. Shade tolerance studies on bermudagrass and other
turfgrasses. Agron. J. 58:523-525.
Powell, J. B., G. W. Burton, and J. R. Young. 1974. Mutation induced in vegetatively
propagated turf bermudagrasses by gamma radiation. Crop Sci. 14:327-330.
Reinert, J. A. and P. Busey. 1983.
Resistance of bermudagrass selections to the tropical sod webworm (Lepidoptera:
Pyralidae). Environ. Entomol. 12:1844-1845.
Reinert, J. A. and P. Busey. 1984. Resistant varieties pp. 35-40. In: Walker, T. J. (ed.)
Mole crickets in Florida. Univ. Florida Agric. Exp. Stn. Bull. 846.
Reinert, J. A., A. E. Dudeck, and G. H. Snyder. 1978. Resistance in bermudagrass to the
bermudagrass mite. Environ. Entomol. 7:885-888.
Simmonds, N. W. 1972. Principles of crop improvement. Longman, London.
Tarjan, A. C. and P. Busey. 1985.
Genotypic variability of bermudagrass damage by ectoparasitic nematodes. HortScience
20:675-676.
Thompson, W. R., Jr. 1965. Vegetative identification of 16 varieties of turf-type
bermudagrass (Cynodon spp.). Bull. Fla. Turf-Grass Assn. 12(1):6-8.
Tracy, S. M. 1917. Bermuda grass. United States Dept. of Agric. Farmers' Bull. 814., USDA,
Washington, DC.
Wofford, D. S. and A. A. Baltensperger. 1985. Heritability estimates for turfgrass
characteristics in bermudagrass. Crop Sci. 25:133-136.
Youngner, V. B. and F. J. Nudge. 1980. Air pollution oxidant effects on cool-season and
warm-season turfgrasses. Agron. J. 72:169-170. |
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