Today’s Forecast: A Daytime High Of 90 degrees And A 50 Percent Chance Of Afternoon Thunderstorms July 8, 2014 By John H. Foy

Mower scalping damage and slower putting green speeds have been common issues during recent Course Consulting Service visits. Both of these issues are a result of rapid bermudagrass growth that has been occurring in response to hot temperatures and abundant rainfall.

For Florida, the daily weather forecast during the summer can be quite monotonous. Everyone knows that it is going to be very hot, it’s going to be very humid, and that there is a good chance for a thunderstorm in the afternoon. A lot of people also assume this is the ideal forecast for growing grass and maintaining good golf course conditions. It is true that warm-season grasses, such as bermudagrass and seashore paspalum, are growing actively in response to constant hot temperatures and abundant rainfall, but rapid turf growth does not directly correspond with making it easy to maintain consistent, good quality course conditions. This is especially true when it comes to putting greens and providing a smooth, true ball roll and a medium-fast to fast putting speed.

During recent Course Consulting Service visits, one of the more common questions from course officials and golfers has been why putting speeds are noticeably slower in the summer compared to the winter. This is in addition to the usual questions about why superintendents frequently core aerate putting greens during the summer. The simple answer to both questions is because the turf is actively growing. During the long, hot, humid days of summer, bermudagrass putting greens are growing actively, resulting in greater resistance to ball roll and a slower putting speed. This is true even when efforts are made to limit the growth rate of the turf through judicious nitrogen fertilization.

Mower scalping damage on putting greens has also been a management concern encountered on recent site visits and is also a consequence of rapid turf growth. Frequent, and at times heavy, rainfall that results in the persistence of wet, soft surface conditions can further exacerbate scalping problems and the challenge of maintaining putting speeds consistent with desires and expectations.

The turfgrass growth regulator trinexapac-ethyl is used in the summer management programs at several courses throughout the region because it can help maintain a more consistent and slightly faster putting speed throughout the day and from one day to the next. This is accomplished by slowing down the shoot growth rate of the turf. An additional benefit of trinexapac-ethyl applications is reduced mower scalping damage. Trinexapac-ethyl has been used extensively over the years with no adverse side effects and the low application rate makes it a cost-effective management tool. However, during the mid-to-latter part of the summer when bermudagrass putting greens are growing very rapidly, maintaining a consistent degree of growth regulation can become more difficult. Making growth regulator applications on a seven-day interval has been standard practice. Furthermore, to maintain a more constant growth rate, the per-acre application rate of growth regulator is gradually increased as summer progresses. An alternative approach that has been providing very good results is to reduce the application frequency to five-day intervals instead of increasing the application rate. Making applications on a rotation of Monday, Friday, and following Wednesday is a common schedule being used to reduce the interval between treatments. Based on the results that are being achieved, use of a five-day treatment interval rather than increasing application rates should be considered if logistically possible.

Finally, core aeration of bermudagrass putting greens in Florida is an absolutely necessary practice for reducing annual thatch/organic matter accumulation. Aeration will never be a popular practice because of the disruptions and inconveniences caused, but conducting two-to-four aerations annually is needed. Core aeration should be performed during the summer growing season so that the turf is able to recover as quickly as possible.

Source: John Foy (

Information on the USGA’s Course Consulting Service  

Contact the Green Section Staff