Dethatching Putting Greens in the Southeast Becomes PopularUpdated 9 MARCH 2000 By: Patrick O'Brien and Christopher Hartwiger, USGA SE Region Agronomists The snow has finally melted in the SE Region and golf superintendents are preparing their putting greens for the busy spring golf season. At bentgrass courses, dethatching putting greens has become almost standard practice today due to the high thatch production of the new heat tolerant bentgrasses. Also, new equipment that does a much better job of dethatching makes it more tolerable for the golfers. In fact, most golfers seldom complain after this maintenance operation since the putting surface is disrupted far less than compared to the 13mm or 20mm hollow tine aeration. At Pinehurst #8 Course, golf course Superintendent, Jeff Hill ran the new Graden dethatching vertical mower through his G-2 bentgrass putting greens the week of February 21st. The 2mm size blades on the Graden were set to a depth of approximately 25mm. The large amount of debris brought to the surface was pushed off with shovels (snow shovels are used at Pinehurst). Usually, the debris is blown off the surface, but the moisture in the mat layer due to recent rains made it too heavy for the blowers. With three Graden machines and seven labourers to shovel the debris, it took almost 11 hours to complete the dethatching project on the large Fazio-designed greens that average 8,000 sq.ft. After the debris removal, the greens were top dressed with 100% sand using a Terratopper. Approximately 1 to 1.5 hoppers per green were applied to fill the grooves from the Graden machine. A few grooves did seal due to the moisture in the rootzone, but it was not a big issue. In early March, two weeks after the dethatching, "the putting surfaces are now 90 to 95% recovered," according to Jeff Hill. No complaints were registered by any of the resort guests at Pinehurst #8. It took two sets of blades to complete the project at Pinehurst #8. Three blade sizes are sold for the Graden with the standard 2mm the most popular. Other available sizes include 1mm for less aggressive dethatching and 3mm for aggressive dethatching. A Swingwing Graden unit also is available that is basically three Gradens tied together. It is operated by a PTO on a small tractor (minimum 35hp). This unit is most popular for bermudagrass putting greens. Pinehurst #8 will again dethatch in early May provided the volcanic heat of the SE Region still has not arrived. Another dethatching is planned during November. This strategy has prevented any excessive thatch development at the Pinehurst #8 putting greens since construction in 1995.
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