Managing Ultra-dwarf Greens

Ronald Strahan, Koske, Thomas J.  |  3/12/2009 8:54:14 PM


Sample the root zone profile often to evaluate thatch buildup and rooting.

Coring should remove a plug of thatch and be followed by sanding to fill these holes.

At our state Turfgrass Conference, one can pick up many useful suggestions from experts in turfgrass management. Over the years we have heard from Bud White, who is director of our region for the USGA Greens Section. A review of his lectures can be very helpful to those managers who don’t have the perfect green.

Most high-end golf courses in Louisiana play on high-speed, dense, ultra-dwarf bermudagrasses like TifEagle, Champion or Mini Verde. These new-generation grasses can be wonderful but unforgiving compared to older grasses like TifDwarf or TifGreen. The main issue is thatch management. Champion, for example, produces about 11 times more thatch than TifDwarf if not managed to correct this tendency.

This growth is both a boon and a bane for this very dense ultra-dwarf. Thus, we should not over grow this grass or fall short on thatch reduction efforts. If thatch gets too thick and tight, it creates a seal that hinders the sod. TifDwarf is about 60% stolons and 40% rhizomes; whereas these ultras are more like 80% stolons and 20% rhizome according to White. But those ultra stolons can become very tight and dense.

In general, light vertical mowing is done 2 to 4 times a month in the growing season with close-centered blades. A weekly, light topdressing should also be considered as standard practice. Your best program will depend on how well what you do is controlling thatch buildup in your production situation. If greens are getting to puffy from thatch, don't depend on verticutting as much and increase your topdressing frequency.

Deeper grooving at ½” will require the organic matter to be swept or blown off. It’s a good idea to follow this procedure with a sanding to fill these larger grooves. If the vertical mowing is doing too much damage, reduce the frequency or make sure it’s only about ¼-inch deep or space the blades wider.

You can occasionally deep verticut to 1”, but be sure to have a wider, 1” spacing between blades and follow with debris removal plus sanding with greens-grade sand topdressing.

If grooming your greens employs a brush, beware of excessive bruising and resulting Bipolaris diseases in mild weather or Curvularia diseases in hot weather.

Deep-tine aerification is fine for heavier mixes, but well-built greens -- using greens-grade sand -- may not benefit much from this extreme aerification. Standard core aerification should be performed several times during the growing season to the extent that 20% to 30% of the upper root zone is removed annually. This may require tighter spacing of the tines. Tines must be large enough in diameter to bring out thatch and not clog.

Remove cores and organic debris when they are brought to the surface. Objection to coring greens may be reduced if greens are swept clean, sanded lightly and rolled smooth. Holes may not look good, but a rough surface will not be tolerated.

Aerify during the growing season so the sod will repair quickly. Mid-spring is good, and late spring is even better. Early August aeration can help promote deeper roots during this stressful time.

Your fertilizer program should give you just enough growth to keep ahead of disease and wear. Six pounds of nitrogen (N) per 1,000 sq. ft. per season may be a little "short" except for Champion, but 10 pounds is likely too much for a mature ultra-dwarf green in Louisiana. TifDwarf and TifGreen are usually fertilized 25% to 35% more than the ultra-dwarfs and must also be managed for thatch.

Fertilize with about as much potassium as nitrogen and maybe 50% more potassium during very stressful times.

If localized dry spots appear, it’s a good bet that thatch or organic mat density has gotten away from you. Pull some profile slab samples and evaluate the thatch. Hand water these spots and use a wetting agent until you can open up the sod and manage down the thatch.

Greens will vary with construction, grass, location, etc., so best management may require any or all of these practices. Again, pull some profile slab samples to 6 inches deep and evaluate the thatch to see if your program needs to adjust more or less.

More information on greens and golf course management can be found at this USGA site.

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