TifEagle Information

      Bermudagrass, Cynodon spp., is a warm-season, perennial, sod-forming grass that spreads by stolons and rhizomes. Bermudagrass probably originated in Africa and Southern Asia. It has been introduced to all tropical and subtropical regions of the world.

      Bermudagrass can be used to produce an attractive wear-resistant turf if managed properly. Both common and triploid hybrid types are used for turf. Common types have 2n=4x=36 chromosomes and usually produce seeds. Triploid hybrids have 2n=3x=27 chromosomes and are male and female sterile. Both can be propagated by stolons and/or rhizomes. Only common bermudagrass types can be propagated by seeds.

      Tifdwarf has been the cultivar of choice for most high-quality bermudagrass putting greens which are mowed at .250 inch or less in the latitudes approximately, 32 degrees north and south of the equator. Tifdwarf is a fine 2n=3x=27 chromosome cultivar selected in 1963 as a small patch about 460 mm in diameter growing on a golf green at the Country Club of Florence, SC. It was evaluated and released in 1966 by Glenn Burton, USDA-ARS and Georgia Coastal Plain Experiment Station.

      Tifway II is a medium fine 2n=3x=27 chromosome cultivar induced in dormant Tifway stolons with 9,000 rads of gamma radiation. It was released by the USDA-ARS and the Georgia Coastal Plain Experiment Station in 1981 by Glenn Burton. Tifway II has good pest resistance and wear tolerance.

      When Tifdwarf was released, the average stimpmeter measure of golf green putting speed was typically between 6 and 7 feet. Tournament play in some locations would be in the 9+ feet range. The minimum requirement on most courses for routine member play today is 8-9 feet with goal of 10+. Golf course superintendents achieve such speeds by reduced mowing heights, overseeding during cool months, frequent topdressing, verticutting, grooming and minimal use of water and nitrogen. Tifdwarf's normal response to mowing heights below .188 is loss of stand density and turf quality. Spring regrowth is further compromised when physiologically stressed turf is overseeded. Weeds and algae become competitive with Tifdwarf and further reduce putting surface quality. A bermudagrass variety was needed that could be routinely mowed at .125 inch or lower and overseeded without loss of stand density and putting quality.

      TifEagle is a fine-textured 2n=3x=27 chromosome mutant derived by irradiating Tifway II stolons. Dormant stolons, obtained from Glenn W. Burton, were treated with 7000 rads of Cobalt 60 radiation on January 12, 1988. Radiation treated stolons were planted in steam-sterilized soil in the greenhouse at Tifton, GA immediately after treatment. Forty-eight putative mutants were selected and individually propagated (45 survived). On July 11, 1988, each surviving mutant was planted in the center of separate 1.8 x 2.6 m plots and allowed to spread to full coverage. Beginning in April, 1989 and continuing through the 1990 growing season, the plots were mowed at .250 inch 3 times per week. In July 1990, a dense fined textured off-type was identified in putative mutant #2. Stolons from this plant were vegetatively increased, tested as TW72 and later named TifEagle.

      TifEagle has been evaluated in four replicated experiments at Tifton, GA since 1991, in nine replicated experiments by scientists in GA, FL, TX, SC, AL and OK, beginning in 1994 and on 24 golf courses in GA, FL, AL, CA, NC, TX, TN, MS, SC and AZ beginning in 1995. Tifgreen or Tifdwarf was used as the check variety at all testing locations. TifEagle has also been planted in Barbados and Argentina. Significant differences refer to the P=0.05 probability level, unless otherwise indicated.

      In four experiments at Tifton, GA, TifEagle produced equal or significantly better quality turf than Tifdwarf when mowed at .250 inch (Table 1). The improved quality of TifEagle appeared to be more pronounced as the turf matured (note 1991, 1994 and 1995 tests in Table 1).

      Table 1. Turf quality of Tifdwarf and TifEagle bermudagrass mowed at .250 inch at Tifton, GA (This is a yearly summary for the tests at Tifton, GA).

      Turf quality of TifEagle was superior to Tifdwarf or Tifgreen at most locations when regularly mowed at .125 to .200 inch. Means for turf quality ratings on six golf courses for 1994, 1995 and 1996 are summarized tin Tables 2 and 3. The 1997 ratings for turf quality on golf courses are summarized in Tables 4 and 5.

      Table 2. Means of 1995 and 1996 turf quality ratings on Tifdwarf and TifEagle bermudagrasses.

      Table 3. Mean turf ratings of Tifdwarf, Tifgreen and TifEagle bermudagrasses.

      Table 4. 1997 turf ratings on TifEagle and Tifdwarf bermudagrasses.

      Table 5. 1997 Turf ratings on TifEagle and Tifdwarf bermudagrasses.

      Established TifEagle greens have been successfully overseeded on several golf courses. Turf quality ratings from two golf courses are summarized in Table 6 and show that TifEagle and Tifdwarf have equal overseeded turf quality. Eight courses used Poa trivalis or a Poa/bentgrass mixture and one used ryegrass. There have been no reports of unusual difficulty in establishing the overseeded species. Golf course superintendents have reported that the dense growth habit of TifEagle causes the leaves of the overseeded variety to grow upright which gives a cleaner cut and better putting surface. Superintendents have also reported that they experienced no unusual problems in spring transition.

      Table 6. Turf quality ratings on overseeded² TifEagle and Tifdwarf bermudagrasses.

      No seed heads have been observed on TifEagle at Tifton, GA (Table 7) and no seed heads have been reported by any of the testing locations. When managed specifically for seed head production to facilitate genetic purity inspections, TifEagle does produce limited numbers of seedheads, but significantly less than Tifdwarf or Tifgreen. TifEagle seed heads are morphologically similar to Tifdwarf.

      Table 7. Ratings for number of seed heads on turf bermudagrass mowed at .250 inch.

      At a .125 inch mowing height, TifEagle had significantly better color than Tifdwarf or Tifgreen (Table 8). This is in large part due to the greater leaf area of TifEagle compared to Tifdwarf at this mowing height. At a .250 inch mowing height, TifEagle has a subtle lighter green color than Tifdwarf, but darker green than Tifgreen. The difference between TifEagle and Tifdwarf is more noticeable with low nitrogen fertility and if they are growing side by side. It is probably due to less anthocyanin in leaves of TifEagle than in Tifdwarf. It is reflected also in improved color and less red plant discoloration, in cool conditions.

      Table 8. Color ratings on TifEagle and Tifdwarf (or Tifgreen at Memphis CC) bermudagrasses.

      After the year of establishment and in high populations of tawny mole crickets (Scapteriscus vicinus) TifEagle showed significantly less damage to this insect than Tifdwarf (Table 9). TifEagle is not resistant to Tawny Mole Crickets, but the insects appear to prefer it less than other grasses.

      Table 9. Ratings for tawny mole cricket resistance¹ on the TifEagle and Tifdwarf bermudagrasses.

      The dense growth of TifEagle can result in significantly more thatch accumulation compared to Tifdwarf. The accumulation of excessive thatch can be PREVENTED by topdressing, verticutting and grooming (Table 10). If TifEagle is poorly managed such that a thick thatch layer accumulates the result will be a scalped, spongy, low quality putting surface. Therefore, management should emphasize thatch prevention during active bermudagrass growth.

      Table 10. Relative thatch accumulation (mm) by TifEagle and Tifdwarf when mowed at .250 inch and verticut heavily once per year.

	1991 Test 1994	1992 Test 1994
TifEagle	20.1	20.5
Tifdwarf	15.1	13.8
LSD (0.05)	1.4	4.5

      TifEagle has not been tested against the entire complex of diseases, insects and nematodes which may infest bermudagrass. However, the only two problems encountered during the testing of TifEagle has been low levels of dollar spot and helminthsporum with Nitrogen and Potassium deficiency respectively. Neither disease was evident with adequate nutrition.

      TifEagle outperformed four other dwarf bermudagrasses in visual ratings of a sting nematode experiment conducted by Robin Giblin-Davis and Monica Elliott in Florida.

      In 7 week-old unmowed plots, green shoot weight of TifEagle (8.65g) was similar to Tifdwarf (7.24g). Number of shoots per 1963 mm² for TifEagle (129) was significantly higher than for Tifdwarf (103). Shoot length of TifEagle (17.8 mm) was significantly less than for Tifdwarf (22.5 mm). Leaves of TifEagle (10.2 mm) were significantly shorter than those of Tifdwarf (13.4 mm). Leaves of TifEagle (1.14mm) were significantly narrower than those of Tifdwarf (1.28 mm). Lengths of the first and third fully extended internodes of TifEagle (10.5 and 10.3 mm) from the end of a juvenile stolon were significantly shorter than those of Tifdwarf (13.2 and 11.8 mm), respectively.

      The fluorescent-labeled AFLP method was used to identify DNA fragments to distinguished TifEagle, Tifway II and Tifdwarf. Tifway II is morphologically distinct (taller and coarser) from TifEagle and the primer pair M-CAT/E-ACC was used to detect 10 DNA fragments unique to TifEagle in the 320 to 500 bp range, but not present in Tifway II. TifEagle and Tifdwarf are more similar in growth habit but are easily distinguished by AFLP techniques. The primer pair M-CAT/E-ACC was used to identify three DNA fragments in the 210 to 325 bp range and two DNA fragments in the 600 to 640 bp range found in Tifdwarf, but not in TifEagle.

      No offtype plants were observed or reported in TifEagle from 1990 to 1997 while it was being evaluated in research plots at Tifton, GA, in research plots at public institutions or at golf facilities. One off-type plant that could be mutant was identified in 1997 in the 12 acre Foundation field of TifEagle. This off-type plant was killed.

      TifEagle is a biological system that is subject to genetic changes as is all biological material. Production procedures have been implemented to minimize off-types in TifEagle planting material. Procedures include a specific life span for sod and sprig fields and the requirement for certified fields to be established directly from foundation stock. Additional precautions may be implemented as TifEagle's genetic stability is further defined.

      TifEagle is male and female sterile and therefore has to be vegetatively propagated. It has been patented by USDA/ARS. TifEagle will be commercially available from licensed sprig and sod producers. Since TifEagle is a patented variety, unauthorized propagation, sale or gifts are prohibited. Morphology and DNA fingerprints will be used to identify unauthorized use of TifEagle propagation.

      The author appreciates the cooperative research support which provided valuable data for TifEagle. The successful release of the variety and development of production guidelines could not have been accomplished without the generous participation by golf course superintendents. The author's gratitude is especially extended to the golf course superintendent cooperators and to Earl Elsner, Director of Georgia Seed Development Commission.