Tifdwarf or Ultradwarf Greens

by Clive "Spud" Williams

I am in an exciting and fortunate position of having the opportunity to renovate an existing golf course in South Florida that I am currently employed at. With all the architectural drawings completed, irrigation pumps, controllers and heads all decided on, I am faced with the decision on whether to recommend a Tifdwarf or an ultradwarf bermudagrass for our new greens.

Like many others, I am familiar with the maintenance requirements necessary for Tifdwarf greens, but am constantly forced by the public to increase the putting speeds of the greens. Now with the introduction of ultradwarf varieties, with a higher shoot density, finer texture and mowing height (as low as 1/10th inch) that creates a smoother and faster putting surface, has sparked the interest of many superintendents and players alike. The only problem being, the high quality-putting surface produced doesn't come without its consequences to the turfgrass manager of the increased maintenance that they require.

So now I am faced with the decision of which to use. Tifdwarf, with its reduced mowing heights to satisfy the putting speeds of today's golfer, can lead to a poor quality of turf requiring additional maintenance. Or an Ultradwarf, that require greater cultural practices to maintain a healthier turf on a daily basis but produce faster and a higher quality-putting surface for the golfers all year round.

History

Before 1956, common seeded bermudagrass (Cynodon dactylon) was used on putting greens in the humid warm climates. In the early 50s, Tifgreen (Cynodon dactylon x C. transvaalensis) was seen as a tremendous breakthrough as it could sustain a good shoot density, while being mown at 1/4 inch. In the 60s, the hybrid Tifdwarf (a natural mutation selected out of Tifgreen) showed a better density than Tifgreen (often referred to as 328) as mowing heights could be lowered to 3/16th inch on putting greens and had a darker green color. Golfers accepted these mowing heights for over 40 years until the introduction of the new "ultradwarf" varieties with their mowing capabilities of 1/8th inch and lower.

Tifdwarf

Tifdwarf Bermuda grass, released in 1960 became the dominant variety for Florida golf course greens. The average stimpmeter measurement of golf green putting surfaces was between 6 and 7 feet. Today, golfers require speeds from the 8 to 10 feet range. To increase the putting speeds of the greens, one is forced to reduce mowing heights, frequently verticut and topdress greens, minimize the use of water and fertilizer, and overseed during the winter months.

Photograph taken on a research green (2x3meter plot) at Jupiter Island Club. The green was mowed that morning at 1/8th inch. The Tifdwarf was sprigged on June 19th 1998 on a green built to USGA specification

Because of the increased stress from low mowing heights on our Tifdwarf greens, we have experienced problems from bermudagrass decline (Gaeumannomyces graminis). One of the most important components of turfgrass quality is density. Of particular concern for bermudagrass greens is maintaining shoot density at increasingly lower mowing heights. Adequate shoot density becomes critical in order to prevent sunlight from reaching the surface of the soil. When shoot density is not adequate problems can begin. Competitiveness against off-type bermudagrass species and weed invasion occur, and given the daily irrigation most greens require, algae can begin to grow on the soil.

Picture showing a putting surface being mowed at 11/64th inch. The stress from the constant low height has created a weak low density of turf

Plugs had to be inserted along with raising the height of cut to help enhance new growth.

Ultradwarfs

The new hybrid bermudagrass cultivars tend to be dominated more by the C. transvaalensis (African bermudagrass) characteristics of the hybrid such as higher shoot to leaf density, slower vertical leaf extension and an increased dominance of stoloniferous related to rhizomes.

Genetics controlled two critical growth characteristics of the dwarf grasses (1):

* Vertical shoot components including the potential vertical leaf growth extension rate and the inherent relative leaf length.

* Horizontal shoot components include the internode length genetic potential, internode density genetic potential and outward growth rate of the lateral stems, especially the stolons.

Advantages:

Shoot density of ultradwarf bermudagrasses (90 to 120 shoots per square inch) is greater than that of Tifdwarf (60 to 70 shoots per square inch) when mowed at 1/8th inch or less (3). The density is increased due to the many short stolons with short internodes and the fine texture of the leaf blades. This creates a faster more consistent putting surface because of the less resistance to ball roll.

The very dense and aggressive lateral growth has many advantages. The extreme low mowing heights of the ultradwarfs allow them to dominate other grasses at greens heights. The lack of vertical growth means there is less to cut and a more rapid turf recovery from damage caused by ball marks and animals. The improved turf recovery rate will provide a better quality turf surface under intense use and also will result in reduced susceptibility to weed invasion.

Disadvantages:

Ultradwarf bermudagrasses have shorter rhizomes but produce more stolons. The combination of the high shoot and stolon density has a strong tendency to produce thatch. This can inhibit drainage, reduce movement of fertilizers and herbicides into the soil and boost the activities of some common insect pests. If the necessary cultural practices are not performed while mowing at these low heights, a thick layer of thatch accumulates resulting in a scalped, spongy, low quality-putting surface.

Establishment and management of ultradwarfs are similar to Tifdwarf, except that more attention needs to be given to thatch prevention. Enough nitrogen should be applied to produce healthy turf. Too much nitrogen can enhance thatch buildup, which must be addressed in a maintenance program. It can be minimized by the use of groomers attached to the greens mowers and a frequent vertical mowing program during the growing months. Topdressing with a light dusting of sand two to three times a month is crucial to producing a smooth putting surface.

Varieties of Ultradwarfs

There are currently five different varieties of ultradwarfs available. There are the "vertical dwarf" varieties of Champion, Mini Verde and MS Supreme, which exhibit slower vertical leaf extension and a faster lateral stem development than the standard variety, Tifdwarf (4). The second group, composed of TifEagle and FloraDwarf, could be characterized as having a slower vertical leaf extension, but a lateral development rate similar to Tifdwarf's (4).

The following photographs were taken on a research green (2x3meter plot) at Jupiter Island Club. The green was mowed that morning at 1/8th inch. The Tifdwarf was sprigged on June 19th 1998 on a green built to USGA specification.

Champion (Coastal Turf Inc)

Developed by father and sons team Richard Morris Brown, Michael A. Brown and Scott D. Brown of Coastal Turf Inc. Bay City Texas.

The developers report that Champion was found in 1987 in a segregated patch on a Tifdwarf putting green in Southeast Texas (1).

MS Supreme (Mississippi state University).

Developed by Jeff Krans Ph.D., and Wayne Philly at MSU. This bermudagrass clone was collected and given to MSU by Boots Lang from Gulf Shores Golf Club, Gulf Shores, Ala. It originated from a Tifgreen bermudagrass green planted in 1964 (1).

TifEagle: - (Georgia Coastal Plain Experiment Station).

Developed by Dr Wayne Hanna, USDA turfgrass breeder at Tifton GA. It originated from Cobalt 60 gamma irradiated Tifway 2 stolons. Sixty-four mutants were identified and propagated as single propagules from the radiation treatments. They were planted July 1988 in 1.8 x 2.6-m plots and maintained at 6mm mowing heights (1).

FloraDwarf (University of Florida)

Developed by Al E. Dudeck, Ph.D., of the University of Florida, and Chuck L. Murdock, professor emeritus, University of Hawaii at Manoa. Believed to be a natural mutation of Tifgreen bermudagrass that was discovered in 1988, at Wailua Municipal Golf Course on the Island of Kauai, Hawaii, (2).

Conclusion

It is important for superintendents to educate the golfers and greens committees about how lowering cutting heights could affect their game of golf. If we continue to reduce heights on the greens we will continue to run the increased risk of getting more diseases on the putting surfaces, and consequently reducing the health of the grass.

These new ultradwarf cultivars are built for speed, and are unique in ongoing challenges to improve the standard of golf course putting surfaces. Managing them requires more labor and cost intensive practices and superintendents should only consider them if they have the equipment, budget, and labor to properly care for them.

With the new ultradwarf s still in their infancy, there is still much to learn about the required maintenance needed. If you ask two superintendents how they manage their new ultradwarf greens you get two different answers (much like Tifdwarf).

Preventing thatch accumulation is the key to success in maintaining any quality bermudagrass greens but do these additional labor costs outweigh the number of times you are constantly forced every year to send employees out onto the greens to hand topdress and plug certain weak areas due to the constant lowering of greens heights to increase putting speed.

Superintendents who have an open mind, a sharp knowledgeable eye, a lot of flexibility, and probably above all, patience with the new management needs of these grasses will be rewarded with the turf quality that often exceeds that of Tifdwarf.

Author's decision

As far as making a recommendation to which grass I would choose, it would have to be an ultradwarf. These are definitely the grasses of the future and there is not a better time than to start now on a newly renovated golf course. It wasn't until I was able to see all the grasses mowed at 1/8th inch side-by-side on the research green at Jupiter Island Golf course (a must for anybody going through the same situation) that confirmed my recommendation.

I feel that TifEagle with its growth characteristics is best suited to produce a healthy green at a 1/8th inch mowing height all year long with no reason to overseed during the winter months. With a lateral growth similar to Tifdwarf, it should produce a little less thatch than the other ultradwarf varieties.

I am excited and prepared to take on the challenge of new maintenance approaches to maintain a healthy turf with the budget and manpower available to me. When it comes down to it, the increased maintenance will not become a problem, as the increased quality of the putting surfaces will be well worth the effort. That's what gets me out of bed early every day, the challenge to improve the quality or the golf course for all to enjoy while they play their round of golf

References

1. Beard, J. B. 1996. Bermudagrass breakthrough: New cultivars for Southern putting greens. Golf Course Management 64(12): 58-62

2. Dudeck, A.E. 1997. Introducing FloraDwarf. Florida Turf Digest, Journal of the Florida Turfgrass Assoc. July-August, p.8.

3. Guertal, B., and R. White. 1998. Dwarf bermudagrasses demand unique care. Golf Course Management 66(7): 58-60

4. Gray, J. L. 1999. Maintaining the new dwarf greens-type bermudagrasses: Research reveals cultivars' similarities and differences. Golf Course Management 67(3): 51-65.

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