As USGA agronomists travel throughout their regions, they benefit from seeing many golf courses in relatively short periods of time. Seeing so many golf courses helps them identify trends in turfgrass conditions. For example, three golf courses in the Southeast with ultradwarf bermudagrass putting greens reported signs of scalping over the last 10 days. The first signs occurred when mowing over unrepaired or partially repaired ball marks. The raised turf caused bedknives to grab the edges of ball marks, scalping anywhere from a few inches to a few feet of the putting surfaces. But ball marks are not the only cause of scalping. The following observations provide a few valuable clues to help explain scalping issues:
Is there a mower setup problem? Perhaps.
It is common sense that inconsistencies in mower setup are magnified, and the risk of scalping increases, as the effective height of cut goes lower. When taking into account the height of the turf canopy and the thickness of the bedknife, often there is little clearance between the two. In the article, “Managing Mower Setup to Achieve Quality Putting Surfaces,” the recommended clearance between the bottom of the bedknife and the top of the turf canopy is at least 0.030 inch. As this clearance decreases, the likelihood of scalping increases.
Is there a height-of-cut issue? Maybe.
Mower setup is a complex topic. However, one thought to consider is that the aggressiveness of mower setup is determined in large part by bedknife angle of attack and the position of the bed bar. Generally speaking, the more aggressive the setup, the higher the bench height of cut can be without altering the effective height of cut on the putting green. An aggressive setup can provide additional clearance between the bottom of the bedknife and the top of the turf canopy. This can help prevent scalping when the mower encounters surface imperfections such as ball marks, when the mower is leaning strongly to one side while mowing a slope or when lowering the cutting unit after making a turn. If you are interested in learning more about mower setup, these resources are highly recommended:
“Managing Mower Setup to Achieve Quality Putting Surfaces” – This article provides a comprehensive review of all aspects related to putting green mower setup.
“Mower Setup Impacts Putting Green Surface Quality” – This webcast discusses and demonstrates the various aspects of mower setup.
Is the turf trying to tell you something? Yes it is.
The turf is telling you that the growing season has arrived. It is telling you that scalping is only going to get worse unless you accordingly adjust mower setup, topdressing frequency and volume, and the frequency of light vertical mowing.
Although scalping is common, there are steps that can be taken to greatly reduce the risk of it occurring. Finding a solution requires patience and the manipulation of numerous variables. USGA agronomists are available to help with this topic and more.
Southeast Region Agronomists:
Chris Hartwiger, director, USGA Course Consulting Service – firstname.lastname@example.org
Steve Kammerer, regional director – email@example.com
Patrick M. O’Brien, agronomist – firstname.lastname@example.org
Todd Lowe, agronomist – email@example.com