COURSE CARE
Championship Green Speed August 6, 2013 By Brian Whitlark

Ball roll measurements were collected using a USGA Stimpmeter up to three times daily during the recent U.S. Junior Amateur Championship with a goal to provide consistent green speeds.

The intense management practices utilized during USGA championships are neither practical nor desirable for daily play. Nor is the intensive monitoring utilized throughout the championship to ensure the course is prepared appropriately for each day’s play. While a variety of course conditions are measured and adjusted, green speed is one of the most important and therefore is measured frequently. During the recent U.S. Junior Amateur Championship (held July 22 to 27 at Martis Camp Club in Truckee, Calif.), green speed was measured before and after maintenance practices to ensure ball roll, as measured with a USGA Stimpmeter, remained within the target range of 11 feet 8 inches to 12 feet 5 inches. Each green was measured following morning mowing and once again on greens that were rolled. Green speed readings were often taken in the late afternoon as well. The data generated from 11 days of ball roll measurements revealed several characteristics of how green speed was impacted by the mowing and rolling strategies employed during the championship.

  • Rolling increased ball roll distance. In general, rolling greens increased green speed by an average of 10 inches. However, on several occasions ball roll distance only increased two to three inches whereas on other greens ball roll distance increased nearly 24 inches following a roll. Moisture on the greens surface was not the cause for the inconsistent increase in green speed. It is unclear at this time what may have caused the variation in green speed following a rolling event. 
  • Green speed varied during the day. Green speed was measured within 20 minutes of greens being mowed and rolled (between 4:30 to 7:30 a.m.). On average, from eight days of morning and afternoon ball roll data, green speed decreased by 9.5 inches from morning to afternoon. Although the Penn A-4 bentgrass greens were being treated with a plant growth regulator, green speed decreased each day despite dry weather, high temperatures (95°F) and occasionally windy conditions. The decrease in green speed throughout the day was expected because green speeds are often the highest immediately after the greens have been mowed and rolled in the morning. In this agronomist’s experience, regardless of turf variety (bentgrass, Poa annua, bermudagrass or paspalum) or weather conditions, green speeds will decrease from morning to afternoon. Despite what viewers may hear from listening to the television broadcasts, it is rare for green speed to increase throughout the day.
  • Thatch may have played a role in green speed loss during the day. Although based on observations rather than scientific evidence, it appeared that greens with the least amount of thatch retained green speed throughout the day better than greens with higher thatch levels. For example, the firmest greens on the course and those thought to contain the least amount of thatch only lost about three inches of green speed on average from morning to afternoon. Conversely, the least firm greens on the course and those thought to contain higher thatch levels lost 13 inches on average by the late afternoon. The relationship of thatch to green speed and the loss of green speed during the day warrants further research.
  • Green speed varied from green to green. Green speed varied by as many as 19 inches prior to the start of practice rounds, but by the time the Championship officially began the difference was reduced to nine inches. The range of green speeds could have been reduced further but slightly lower speeds were intentionally maintained on the 13th and 16th greens due to steep slopes. The differences in green speed early on in the practice rounds may be attributed to moisture content in the greens, growth rate, microclimate, or variability with the mowers. It is common with any facility to see slightly slower or faster ball roll on one or two greens on the property. With this in mind, it is advised to occasionally collect Stimpmeter measurements on all greens at your facility to gain a better understanding of how greens may perform differently.
  • The combination of mowing and rolling had a cumulative effect on green speed, but plateaued after several days. During the initial three to four days of mowing and rolling, green speeds progressively increased by an average of about five inches but then plateaued once green speeds reached about 12 feet. Ball roll distance remained very consistent over the final three days of the Championship with overall daily averages of 12 feet, 11 feet 11 inches, and 12 feet (measurements were collected after the morning mow and roll).

Source: Brian Whitlark (bwhitlark@usga.org)

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