© 2005 Plant Management Network.
Ball Mark Repair and Creeping Bentgrass Recovery
Jack D. Fry, Professor, Ty A. McClellan, Undergraduate Research Assistant (currently Graduate Research Assistant, Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68583-0915); and Steven J. Keeley, Associate Professor, Department of Horticutlure, Forestry, and Recreation Resources, Kansas State University, Manhattan, KS 66506-5506
Fry, J. D., McClellan, T. A., and Keeley. S. J. 2005. Ball mark repair and creeping bentgrass recovery. Online. Applied Turfgrass Science doi:10.1094/ATS-2005-0801-01-RS.
Ball marks result from golf ball impact on putting greens, and recovery of the surface may depend upon the repair strategy employed. Our objective was to compare three ball mark repair techniques for their influence on golf green surface quality and ‘L-93’ creeping bentgrass (Agrostis palustris Huds.) recovery. Studies were conducted on a practice putting green on a golf course (Study I) and on a research green (Study II) near Manhattan, Kansas. Ball marks were made by a golfer striking golf balls with a pitching wedge from 100 m in Study I and from 70 m in Study II. Five treatments were imposed on the ball marks immediately after they were created: (i) no ball mark (control); (ii) unrepaired ball mark; (iii) Greenfix tool; (iv) traditional ball mark repair tool used improperly; and (v) traditional ball mark repair tool used properly. In both studies, ball marks repaired properly with the traditional tool or with the Greenfix, recovered completely in 16 to 21 days; recovery was 4 days faster with the Greenfix tool than the traditional tool in Study I. Marks repaired with the Greenfix had poorer surface quality due to the presence of an uneven surface at 3 days after the ball mark was made (ABM) in Study I and up to 10 days ABM in Study II. Using the traditional tool improperly resulted in the poorest surface quality at > 17 days ABM due to a persistent ball mark scar and poor turf quality in the mark area. Improperly repaired marks required > 38 days for recovery, 19 days longer than unrepaired marks in Study I, and at least 8 days longer than unrepaired marks in Study II. Proper use of the traditional tool or use of the Greenfix allowed for most rapid improvement in creeping bentgrass surface quality and fewest days to recovery; however, improper use of the traditional tool reduced surface quality and doubled the time for surface recovery compared to its proper use.
Ball marks are created when a golf ball impacts the surface of a putting green, and when left unrepaired or repaired improperly reduce surface quality and trueness of ball roll. The impact of the golf ball displaces turfgrass leaves, stolons, and crowns, and likely compacts the soil at the base and along the perimeter of the ball mark cavity.
Ball mark repair is encouraged by golf professionals and superintendents, and the effort is thought to be rewarded with better surface playability, resulting from leveling of the cavity created by ball impact and sustained quality of turf in the mark area. Many courses provide a traditional two-pronged ball mark repair tool (Fig. 1) for golfer use, sometimes without charge. There is much confusion among golfers, however, about how this tool should be properly used in repairing the ball mark. The Golf Course Superintendents Association of America provides guidelines for repairing ball marks properly with the traditional two-pronged tool (2). Nevertheless, it is likely that some golfers would plead ignorance when asked how to properly use the traditional tool, and attempts to repair ball marks by digging and lifting may injure creeping bentgrass roots, which is not the way it was intended to be used.
A new tool manufactured by Greenfix Golf, Inc. (Phoenix, AZ) has recently been marketed for ball mark repair. The Greenfix tool (Fig. 1) is sold as a pop-up unit that is built into the end of the putter grip or sold independently as a hand-held tool. The two prongs on the putter-end Greenfix are 1.5-cm long and taper from a narrow point at their tip to a 5-mm width at their base. Prongs are separated by a 3-mm void for their entire length. Ball mark repair is accomplished by pushing at the back and around the perimeter of the mark; the prongs are too short to allow for digging and lifting of the depression. Hence, the manufacturer markets the Greenfix tool by listing one potential advantage as a lesser likelihood that the golfer will use the tool improperly compared with use of the traditional tool.
There is little published information on ball mark recovery on creeping bentgrass greens. Information available does provide some indication of the persistence of the ball mark scar, however. Researchers in New Jersey pneumatically ejected golf balls into the surface of a research putting green and compared recovery of unrepaired marks among several creeping bentgrass cultivars (3). Some damage was evident in ‘Penncross’ even 74 days after the ball marks were created. Pennsylvania researchers (4) created ball marks by pounding the lower half of a golf ball into a creeping bentgrass green’s surface, removing the depression with a 40-mm diameter core sampler, and then filling the void with sand. Approximately 40 days after creating marks, 70% recovery in the sand-filled void had occurred.
There are no publications on record that have dealt with ball mark repair and creeping bentgrass recovery. Our objective was to compare three ball mark repair strategies for their effects on putting green surface quality and creeping bentgrass recovery.
Two Experiments Comparing Ball Mark Repair Techniques
Two separate experiments were conducted in consecutive years. Study I was conducted on a practice putting green at the Colbert Hills Golf Course in Manhattan, Kansas from 27 May to 12 July 2003. The experimental area was a five-year-old stand of ‘L-93' creeping bentgrass growing on a green constructed according to the California-style method (1). No defined layer of thatch or mat was present at the soil surface; organic content to a 2.5-cm depth was 4.8 g per 100 g of soil as determined by the Kansas State University Soil Testing Laboratory. Sand topdressing was not applied during the study period, but was normally applied four to five times per year between April and October at a depth of approximately 3 mm.
The green was mowed 7 days weekly at 3 mm with a triplex greens mower, and clippings were collected. Irrigation was applied every 3 to 5 days to provide 2.5 cm of water when adequate rainfall did not occur. Soil tests indicated a P value of 14 mg/kg, a K value of 78 mg/kg, and a pH of 7.7, as determined by the Kansas State University Soil Testing Laboratory. In spring, 2003, N from a source containing 50% methylene ureas was applied at 25 kg/ha on 21 and 25 March, and on 27 May. An additional 17 kg of N per ha from the same source was applied on 29 May. Potassium as K20 was applied at 37 kg/ha on 17 March and 3 June.
Fifty ball marks were created on 27 May 2003, by the impact of golf balls hit by a PGA professional using a pitching wedge from a distance of 100 m. Three ball mark repair treatments, plus a no-ball-mark control and an unrepaired mark, were randomly assigned to the marks within 10 minutes after they were created: (i) no ball mark (control); (ii) unrepaired ball mark; (iii) Greenfix tool; (iv) traditional ball mark repair tool used properly; (v) traditional ball mark repair tool used improperly. No-ball-mark control areas were also randomly assigned across the putting surface. Unrepaired ball marks were not treated at any time during the recovery period. Before repair with the Greenfix tool, prongs attached to the hinge on top of the putter grip were fully extended and snapped into a vertical position. Ball marks were then repaired according to manufacturer’s directions: the putter was inverted, and the prongs were pushed into the ball mark surrounds 4 or 5 times at a 45-degree angle, starting at the back of the mark, i.e., the side of the mark farthest from where the ball was struck (Fig. 2). The mark area was tamped lightly with a putter after repair.
The traditional ball mark repair tool was a standard, metal two-prong tool similar to those available in most golf pro shops (Fig. 1). Individual prongs measured 45 mm long; 4 mm across the front and back, and 2 mm on the sides. The prongs were separated by a 10-mm gap. Proper use of the traditional tool was accomplished by using the method recommended by the Golf Course Superintendents Association of America (2). The prongs were inserted vertically at the back of the mark to a 40-mm depth and a twisting/weaving action was used three or four times around the perimeter of the mark (Fig. 3). The improper use of the traditional tool was accomplished by initially inserting the prongs vertically to a 40-mm depth at the back of the ball mark and then pressing downward on the tool’s grip away from the ball mark and toward the green’s surface so that the prongs lifted the center of the mark until it was at the same level as the surrounding green surface (Fig. 4). This was repeated three or four times around the perimeter of the mark. The mark area was tamped with a putter after repair. A number code was spray painted on the green’s surface immediately adjacent to each mark and no-ball-mark control areas so that researchers could locate and collect data for the appropriate treatments.
Study II was conducted on a six-year-old stand of ‘L-93’ creeping bentgrass growing on a sand-based green at the Rocky Ford Turfgrass Research Center near Manhattan, KS from 17 September to 29 October 2004. This green consisted of 95% sand and 5% silt and clay in the upper 20 cm, with a silt loam base underneath; there were no drainage tiles. There was no well-defined thatch layer, but lack of regular topdressing had contributed to a dark mat layer about 2.5 cm deep that resulted in a relatively "soft" surface compared with that of the Colbert Hills site. Organic matter content to a 2.5-cm depth was 7.6 g per 100 g of soil, as determined by the Kansas State University Soil Testing Laboratory. Core aerification, followed by sand topdressing, had been performed routinely during autumn of each year beginning the year after planting, but was not done during fall 2004. No other sand topdressings were routinely applied except at the time of aerification.
Golf balls were hit from a distance of 70 m with a pitching wedge on 17 September 2004. Ball marks were immediately repaired by using the same methods described in Study I. The green was mowed six days weekly at 4 mm. Irrigation was applied every 3 to 5 days to provide 2.5 cm of water when adequate rainfall did not occur. Soil tests indicated a pH of 7.8, a P value of 46 mg/kg and a K value of 46 mg/kg, as determined by the Kansas State University Soil Testing Laboratory. During 2004, N at 49 kg/ha was applied on 31 March, 25 May, 7 July, 6 October, and 6 November. An additional application of N at 25 kg/ha was made on 9 April. Fertilizer source was a 18-9-18 fertilizer containing 55% slowly available N.
Evaluating Ball Mark Recovery
Data were collected on ball mark volume and scar diameter, surface quality, and days to complete ball mark recovery. Ball mark volume was determined for unrepaired marks immediately after they occurred and once weekly thereafter. Volume was determined by placing a sheet of thin plastic food wrap over the mark and then carefully dropping fine sand onto the wrap to fill the ball mark cavity until the sand was level with the surface of the green. Sand was wrapped tightly inside the plastic wrap and then taken to the laboratory, where sand was poured into a graduated cylinder and volume was measured. Pore space in the sand was not taken into account, but this technique provided a relative measure of ball mark cavity volume.
Ball mark scar diameter was measured 3 days ABM, and then weekly thereafter. A ruler was used to measure each mark in two directions, and the average diameter was calculated.
Surface quality of the ball mark area was rated 3 days ABM and then once weekly, using visual and tactile observations on a 0 to 9 scale where 0 = an uneven surface with dead turf; and 9 = good turf quality and no surface disturbance. More specifically, a relatively smooth surface with dead turf resulted in a surface quality score of about 4. A newly created, unrepaired ball mark cavity that was relatively deep received a score < 2.
Days to complete recovery were determined by inspecting the ball marks every 3 or 4 days; the last evaluation occurred 46 days ABM in Study I and 42 days ABM in Study II. A ball mark was considered recovered when the mark was no longer noticeable from eye level. Once a ball mark was recorded as recovered, a surface quality rating of 9 was assigned for each subsequent week for that particular ball mark area.
Treatments were arranged in a completely randomized design with 10 replicates. Data from each study were analyzed separately because they were conducted at different times of the year and on surfaces that were managed differently. Data were subjected to analysis of variance, and significant (P < 0.05) treatment effects were separated by using a F-protected LSD mean separation test.
Repair Technique by Surface Quality and Recovery Rate
Average volume of all ball marks immediately after they were created was 6.5 cm3 in Study I and 12.1 cm3 in Study II (Fig. 5). The greater volume in Study II was likely due to a softer surface resulting from lack of golfer traffic and routine sand topdressing applications at Rocky Ford. Organic matter content in the surface 2.5 cm was greater at Rocky Ford (7.6 g per 100 g of soil) compared with Colbert Hills (4.8 g per 100 g of soil). Hence, although New Jersey researchers (3) reported greater ball mark injury on immature creeping bentgrass, lack of traffic and a higher organic matter level in the surface 2.5 cm resulted in a softer surface and larger ball mark volume in Study II. At both locations, volume of unrepaired ball marks had declined to < 4 cm3 by 10 days ABM. By 17 days ABM, volume had declined to < 2.5 cm3 at each location.
Although unrepaired ball marks may initially create a significant cavity and influence golf ball roll, within 10 days ABM cavity volumes had shrunk by more than 50%. Decline in ball mark volume over time was attributed to surface resiliency which may have been accelerated by wetting and drying, rolling that resulted from daily mowing, and growth of creeping bentgrass plants inside the ball mark cavity.
Regardless of the ball mark repair tool used, a ball mark "scar" of necrotic turf occurred. Ball mark scars were visible 3 days ABM in all treatments except the control mark areas (Fig. 6). Largest diameter scars were measured throughout each study in marks that were repaired improperly with the traditional tool. At 10 and 17 day ABM in Study I, scars from marks repaired using the Greenfix tool were smaller than those repaired properly with the traditional tool. In Study II, no differences in scar diameter were observed between the Greenfix and the traditional tool used properly. Scar diameters of unrepaired marks were second only to the improperly used traditional tool at 3 and 17 days ABM in Study I and until 31 days ABM in Study II.
Poorest surface quality (i.e., ratings < 4) was observed in unrepaired marks at 3 and 10 days ABM in Study I and at 3, 10, and 17 days ABM in Study II (Fig. 7). Unrepaired marks resulted in cavities that would negatively affect trueness of ball roll.
At 3 days ABM in Study I and at 3 and 10 days ABM in Study II, ball marks repaired with the Greenfix tool had poorer surface quality than did marks repaired properly with the traditional tool (Fig. 7). Presumably, the twisting, weaving action used with the longer-pronged traditional tool resulted in a smoother surface shortly after repair, particularly with the higher-volume depressions in Study II, compared to the pushing motion required by the Greenfix. We did not measure the potential influence of the surface quality on trueness of golf ball roll.
At 17 and 24 days ABM in Study I marks repaired with the Greenfix had superior surface quality to the marks repaired with the traditional tool used properly; in Study II, the two treatments exhibited similar surface quality after 10 days ABM. The improved surface quality with the Greenfix in Study I relative to the properly used traditional tool was due primarily to better turf quality in the mark area. It may be that roots were damaged to a lesser extent by the relatively short prongs and pushing action used with the Greenfix tool, compared to longer prongs and a twisting/weaving actions employed with proper use of the traditional tool.
In marks repaired improperly with the traditional tool, poorest surface quality was observed after 10 days ABM in Study I and after 17 days ABM in Study II (Fig. 7). After using the traditional tool improperly, the surface was relatively smooth, but poor turf quality in the mark area resulted in lower surface-quality scores.
Fewest days to recovery resulted from ball mark repair with the Greenfix tool and from unrepaired ball marks in Study I, and with the Greenfix and proper use of the traditional tool in Study II (Table 1). Trueness of golf ball roll over mark areas was not evaluated and would likely be a concern over unrepaired ball mark cavities.
Table 1. Influence of ball mark repair strategies on days to recovery
x A ball mark was considered to have recovered when the mark was
y Means are an average of 10 replicates. Numbers followed by the
Improper use of the traditional tool resulted in ball mark scars persisting for at least 38 days in each study. Recovery differences were evident at 3, 10, and 24 days ABM in Study I among unrepaired ball marks those repaired properly or improperly with the traditional tool, and those repaired with the Greenfix tool (Fig. 8). In Study II, scars were present when the study concluded at 38 days in each of the replicates that had been repaired improperly with the traditional tool. These scars will likely be present when creeping bentgrass growth resumes the next spring. Results from both studies indicate that not repairing the ball mark at all will result in faster recovery than using the traditional tool improperly will.
Both the properly used traditional tool and the Greenfix tool exhibited advantages at certain times during the two studies. Proper use of the traditional tool resulted in better surface quality than use of the Greenfix tool did for as long as 3 days ABM in Study I and 10 days ABM in Study II, resulting from a more level surface with proper use of the traditional tool. The Greenfix tool provided better surface quality, however, at 17 and 24 days ABM in Study II because turf in the mark area recovered more quickly. Proper use of the traditional tool and use of the Greenfix tool generally provided similar creeping bentgrass surface recovery results. The traditional tool is easily misused, however, which resulted in a recovery period that was twice as long as that observed in ball marks repaired properly or with the Greenfix tool
This is contribution no. 05-239-J of the Kansas Agricultural Experiment Station. Thanks are extended to Mr. David Gourlay, Mr. Chad Meyers, and Mr. Paul Davids for their cooperation at Colbert Hills Golf Course. The statistical assistance provided by Ms. Qi Zhang and video assistance from Dr. Charles Marr was also appreciated. This research was supported, in part, by grants from Greenfix Golf, Inc. and the Kansas Turfgrass Foundation.
1. Christians, N. 2004. Fundamentals of Turfgrass Management. John Wiley and Sons. Hoboken, NJ.
4. Watschke, T. L., Borger, J. A., and Brosnan, J. T. 2001. Evaluations of ball mark recovery on a putting green. Pages 94-96 in: 2001 Annual Research Report. Penn. State Univ.