The fine points of maintaining great hybrid bermudagrass putting greens were highlighted at a recent USGA Surface Management Workshop held in Arizona. This was a hands-on workshop, facilitated by USGA agronomists, that brought together superintendents and assistant superintendents from various parts of Arizona to exchange information and view demonstrations of the latest techniques for managing hybrid bermudagrass putting greens. Here are some key takeaways from the workshop:
- Backtrack mowing – i.e., going back and forth over the same pass – and vertical mowing are very common and effective practices for controlling grain and promoting smooth putting surfaces.
- The same bench setting for different brands and configurations of mowers yields significantly different effective cutting heights. Viewing the putting surface with a prism gauge is the best method for relating the bench setting of a mower to the effective cutting height.
- Many superintendents reported good results with backtrack vertical mowing at a height of 0.0 (even with the front roller) to 0.06 inch below zero at a frequency of one to two times per week during summer. The goal is not thatch reduction, it is managing the aerial stolons that tend to form on the ultradwarf hybrid bermudagrasses.
- Most superintendents agreed that groomer setup is best when using one spacer between blades. Groomer settings generally ranged from 0.085 to 0.1 inch above zero. One superintendent remarked that he groomed daily with the goal of being "gently aggressive."
- Brush attachments continue to be very popular for managing ultradwarf bermudagrasses. There were a wide range of brush setups demonstrated during the workshop, including both forward- and reverse-rotation brushes set at different heights.
- Applying sand topdressing to match the growth rate of the grass is an essential practice during the active growing season. Many superintendents are using a finely graded medium sand with a minimum of particles larger than 1 millimeter in diameter. Application rates typically start at 100 pounds per 1,000 square feet early in the season and increase to 200-300 pounds per 1,000 square feet in the peak of the growing season. While some superintendents were initially concerned that using a finer sand would negatively impact the infiltration rate, this was not found to be the case in the field. Physical soil testing showed that organic matter accumulation was the main factor causing reduced infiltration.
- Watering practices varied among the group, but there were some commonalities. Nearly all the superintendents in attendance were using portable moisture meters to check moisture on putting greens. The preferred moisture content ranged between 20 and 30 percent according to the superintendents in the group. Most superintendents reported irrigating putting greens daily at a light rate with a deeper irrigation – i.e., 2 to 3 hours of watering – once per week during the summer season
West Region Agronomists:
Patrick J. Gross, regional director – pgross@usga.org
Larry W. Gilhuly, agronomist – lgilhuly@usga.org
Brian S. Whitlark, agronomist – bwhitlark@usga.org
Information on the USGA’s Course Consulting Service
