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Key Takeaways

  • Collar decline is a chronic problem on golf courses with a wide range of grass types and maintenance practices.
  • In recent years, better understanding of the factors that lead to poor turf quality in collars has improved management.
  • Eliminating collars has become more common as superintendents and course officials realized that collars are a maintenance headache and do not offer significant enhancement to playability.
  • Understanding the potential issues impacting collar quality on a given golf course is the critical first step in developing solutions.

Putting green collars – sometimes called aprons – are a frequent topic of conversation on USGA Course Consulting Service visits and during USGA championship preparation. This narrow band of grass that separates putting greens from the surrounds garners a lot of attention and generates many questions. Why do our collars struggle? What turfgrass is best for collars? How wide should the collar be? What is the recommended mowing height for collars? Are collars really needed at our course?

Collars are a relatively small, but highly visible, part of the golf course – and they can struggle at courses across the budget spectrum. Advances in mower and sprayer technology have provided options for improving collar management, but these areas still take a lot of abuse and decline is a common occurrence. Understanding the primary reasons for collar issues and identifying which factors might be causing trouble at your course are the key first steps in getting better performance from these hard-to-maintain areas.

The USGA Green Section Record article “Collar Problems and How to Prevent Them” provides a summary of the factors that may affect collar quality. They include mechanical stress from maintenance and golfer traffic, sand abrasion from topdressing, excess leaf tissue making grass more susceptible to mechanical damage, and overspray of plant growth regulators (PGRs). These issues are even more problematic in poor growing environments where the grass is already under stress. In most instances, these different issues work in tandem to create the conditions that are responsible for collar decline. This article is not intended to rehash these factors. Rather, the focus will be on strategies that have emerged to improve collar quality as well as research that has enhanced our understanding of PGR impacts on turf at different heights of cut.

Managing Traffic Stress and Physical Damage

Minimizing collar problems starts with growing healthy grass and reducing mechanical stress. This includes using mats or boards to protect collars from tight mower turns and eliminating overthrow of sand topdressing into collars because the abrasion that comes when sand meets concentrated traffic can be highly injurious. These adjustments are especially critical during times of unfavorable weather.

Practices that promote upright growth, such as grooming and brushing, reduce the leaf area exposed to maintenance practices, which makes the grass less susceptible to damage. Eventually, these practices can help to improve density. Lowering the height of cut can also help in this regard. This might seem counterintuitive, but collars can perform better at a lower height of cut for several reasons. Shorter turf grows more rapidly than taller turf, which improves recuperative potential. Shorter turf also means less leaf area exposed to abrasion or PGR overspray. For cool-season collars, mowing at 0.200 inch or below is becoming more common. Grooming, brushing or lowering the height of cut to improve collar performance must be implemented preventatively, prior to stress and decline occurring, to be effective. They are not “rescue” treatments after turf decline begins.

Triplex mowing of putting greens has become more common, sometimes by choice and sometimes out of necessity due to labor challenges. Many consider the quality of cut from a properly adjusted triplex mower to be comparable to walk-behind mowers and significantly fewer staff hours are required when using triplexes. One of the advantages of triplex mowing is that traffic stress on collars can be reduced because fewer turns are required to mow a green. Nevertheless, operators must be aware of their turns when changing directions as damage can still occur with triplex mowers. If collars show signs of wear from triplex mowing, consider changing the mowing pattern.

In instances where cool-season putting greens are maintained adjacent to warm-season surrounds, collar damage occurs frequently. Often, this is the result of necessary maintenance when weather conditions favor cool-season grass growth, but warm-season grass is entering or exiting dormancy.

Superintendents throughout the transition zone are very familiar with the challenge of trying to maintain cool-season putting green growth and playability without injuring warm-season surrounds during the spring and fall. Damaged areas must be resodded or poor collar conditions tolerated until the warm-season grass recovers. However, potential problems are not limited to spring and fall. Compromised warm-season grasses still struggle to recover during the summer from the injury that occurs in spring and fall. Factors beyond mechanical stress, such as PGR overspray, may continue to affect recovery. Limiting damage during spring and fall is critical to season-long turf quality. Triplex mowing can be beneficial to immediate surrounds during portions of the growing season when warm-season grasses have limited growth because fewer turns are required and they are typically made farther away from the putting green.

Triplex mowers are not the solution to collar problems, but they can help when paired with a careful operator. Many superintendents will continue with walk-behind mowers as their primary putting green mowing option. However, when considering equipment purchases, remember that triplex mowers are versatile and can be used in other areas. They can also help to address labor shortages during the primary season or when seasonal staff have departed.

Limiting PGR Overspray

Overspray of PGRs into collars and surrounds has long been recognized as a problem for turf quality. Like mechanical damage, this problem can be especially bad where warm-season grasses surround cool-season putting greens. However, recent research has shed light on just how problematic growth regulator applications can be for any collar-height turf surrounding a putting green.

PGRs have generally been applied on a calendar interval – i.e., X amount of product every Y days. Research performed at the University of Nebraska (Kreuser et al., 2017) showed the degree of seasonal variation in PGR metabolism and how growing degree day (GDD) accumulation is a better predictor of when reapplications are needed than calendar days. Essentially, under warmer conditions, PGRs are metabolized more quickly and need to be applied more frequently to maintain consistent regulation than they do under cooler conditions.

This research also indicates that turf at putting green height requires more frequent applications of PGRs than fairway- or collar-height turf to maintain steady growth suppression. Depending upon the product selected and turfgrass species established in the collar, the GDD application interval for collar-height turf could be double that of putting green turf. Additionally, relative regulation at the same rate of application is much higher on collar-height turf compared to green-height turf. Even when GDD models are followed for putting green applications, overspray into collars can still lead to severe overregulation. The growth rate of the grass is then inadequate to recover from traffic, which leads to decline.

"Even when GDD models are followed for putting green applications, overspray into collars can still lead to severe overregulation."

Covering collars with carpets during spraying, immediately washing PGRs off the collars after application, or leaving small untreated strips around the edges of putting greens to prevent overspray are all options to limit this problem. However, one of the simplest and most effective solutions is to use GPS sprayers. GPS sprayer technology limits overspray into nontarget areas and individual nozzle control offers very precise application. It is not a perfect solution, but this technology can substantially reduce PGR overspray on collars. While prices for GPS sprayers have decreased, they are still cost prohibitive for many facilities, with new GPS sprayers costing upward of $100,000 and retrofits costing $50,000 or more. Hopefully this technology will become more affordable in the future.

Is a Collar Truly Necessary?

In recent years, more and more golf courses have chosen to eliminate collars entirely. Reasons to eliminate collars include architectural preference, limited playability benefits and repeated instances of collar decline. The purpose of a collar is to provide a buffer between the putting green and primary rough surrounding the green. If the collar transitions directly to rough that is quite tall, one can make a strong argument that a collar is sensible.

However, many courses have an intermediate rough cut maintained around 1 inch in height that already provides a buffer between the green and primary rough. Some courses have a relatively low height of cut for their primary rough to begin with, which makes a collar or intermediate rough cut of marginal benefit. Putting greens can also be surrounded by closely mown areas with a height of cut only slightly higher than the collar. The need for a collar in any of these scenarios is debatable. It is worthwhile to ask whether collars really improve playability at your course or whether they’re just a remnant of the way things have always been done.

Converting collars to putting green turf eliminates the task of mowing collars multiple times per week with a separate mower. Labor scarcity on golf courses is an ongoing reality and removing collars can help eliminate a maintenance headache and allow staff time to be focused on areas that have a more significant impact on playability.

The process of converting collars to putting green turf is not difficult, but it does require planning and proper timing. First, it is important to determine whether the collar is established on soils that are consistent with the putting green soils. If the collar is not maintained on putting green soils, converting the collar to match the surrounds is probably a better option.

In most instances, the collar is maintained on putting green soils and the species of grass in the collar are the same as that of the green, which means these areas will tolerate putting green mowing heights. The steps to convert collar areas to putting green height are as follows:

  • Incrementally reduce collar height of cut while trying to avoid scalping. How quickly the grass can be trained down to putting green height depends on collar height at the beginning of the process. For cool-season grasses, this process is best performed in late summer and fall when growing conditions are favorable. For warm-season grasses, initiate the process in late spring once dormancy has broken and normal growth resumes.
  • As height of cut gets within 1/10 inch of putting green height, light topdressing should be performed three to five days prior to additional height reductions. This helps to protect the crown of the plant as height is reduced further and helps smooth any surface irregularities.
  • Core aeration followed by rolling may be necessary at the old interface between collar and green. This area can become convex over time due to accumulation of topdressing and organic matter. Aeration with small- to medium-sized tines on tight spacing followed by watering and rolling will smooth any irregularities and create an even transition. Surface irregularities can be a maintenance challenge in the first full growing season after converting collars to putting green, but these issues can be addressed by repeating this process.
  • If the grass established in the collars is not the same as that on the putting green, eliminating the collar will be more difficult. Depending upon the circumstances, the best option may be to convert the collar to primary or intermediate rough rather than putting green turf.
  • It is worth noting that a decision to eliminate collars does not have to be permanent. Converting collars to putting green area has several benefits and the vast majority of golf courses that have done away with collars have continued without them. But, if removing collars creates a problem at your course, they can easily be restored.

Final Thoughts

Maintenance intensity on putting greens has placed a lot of stress on surrounding collars. Whether it is mechanical damage, abrasion from topdressing or PGR overspray, collars take a lot of abuse. Evaluating exactly what factors are causing collar decline in an individual situation is critical to improve collar quality, and these factors must be addressed proactively. Once decline begins, it can be very difficult to stop.

Eliminating collars has provided relief from problems on many golf courses and is something that should be considered for those who are looking to simplify maintenance around putting greens. This is not the “be-all/end-all” solution, but should be a consideration based upon the potentially positive impacts collar removal can have on playability and turf performance. Different circumstances call for different solutions, but if you are experiencing chronic collar problems, look carefully at potential options for improvement and don’t be afraid to make adjustments. If you’re struggling with collars year after year, something needs to change.

Darin Bevard is the senior director of championship agronomy and also performs Course Consulting Service Visits in the Northeast Region, where collar problems are a frequent topic of conversation.


Kreuser, W.C., J.R. Young, and M.D. Richardson. 2017. Modeling performance of plant growth regulators. Agricultural & Environmental Letters, 2: 170001. doi: 10.2134/ael2017.01.0001