It has been a long and hot summer, and for courses throughout the eastern two thirds of the country the extreme high temperatures that have been experienced have taken a toll on cool season turfgrasses. Growing up and going to school in Georgia, Labor Day weekend was always an important and anticipated time. Along with marking the beginning of Southeastern Conference football, cooler nighttime temperatures inevitably began to occur and bentgrass putting greens began to recover from summer stress. After 25 years in South Florida, the arrival of Labor Day is still anticipated because of the return of college football, but has a different meaning with respect to golf course management.
For Florida golf courses, the arrival of Labor Day means that it is time to wrap up summertime cultural management programs and projects, and prepping for the upcoming winter season becomes the priority. At courses in Central to South Florida, a final core aeration of putting greens is typically conducted in early to mid-September, and while sustained bermudagrass growth is occurring, the rate of recovery is slowing down. Thus, care needs to be exercised not to cause excessive mechanical damage, and the use of smaller (3/8 to 1/2-inch) diameter tines is advised. Also, while it is important to continue to verticut bermudagrass putting greens during the late summer and early fall to control grain and aide in controlling surface organic matter accumulation, here, too, because intense environmental stress conditions are typically prevailing, it is important to not exert significant additional mechanical stress on the turf and cause a further setback in its health and coverage. At all of the courses recently visited, the verticutting units have been adjusted so that they are only operating at a depth of 1/10 to 1/8 th inch below the effective height of cut. In late September to October, verticutting will be completely discontinued and increased use of mower-mounted brush or groomer attachments will occur.
For at least another six to eight weeks, hot and humid summertime weather conditions will continue to occur in Florida, favorable for sustained warm season turfgrass growth. Regardless of whether or not winter overseeding of bermudagrass putting greens will be performed, it is extremely important that fertilization and other management practices continue to be geared to promote balanced growth, carbohydrate production, and storage. If the health of the bermudagrass has been compromised going into the winter, naturally there is increased potential for problems in the spring when the transition out of the overseeding cover begins to occur. Thus, along with making sure that sufficient levels of available nutrients -- especially potassium -- is maintained, sufficient leaf surface area must be present to support balanced, healthy growth. Maintaining very low heights of cut is even more of a concern at this point because of reduced sunlight conditions and a progressively declining day length. Unfortunately, however, in another few weeks, seasonal golfers will begin returning to Florida, and the pressure for fast to very fast putting speeds will start ramping up. Yet again, if compromises are made now, consequences can be experienced later on during the primary play season.
As an additional comment with respect to sunlight, bermudagrass putting greens have no shade tolerance. A minimum of eight hours of direct sunlight is needed with close-cut bermudagrass putting greens; this past winter the negative impact of shade problems was further increased by the adverse and abnormal weather pattern that occurred. Hopefully, needed vegetation thinning and removal work has already been completed, but if this is not the case, it is certainly not too late to get out the chainsaws, and the turf will still benefit from increased sunlight and air circulation.
Finally, and while already underway at many courses in North Florida, pre-emergent herbicide treatments for winter annual weed control, and especiallyPoa annua, is a necessary and important consideration for Florida golf courses at this time. This past winter there was a bumper crop of Poa annua on many golf courses, and besides being a very prolific seed producer, the seed can remain viable in the soil for up to six years. A free recording of a previous webcast by Dr. Bert McCarty at Clemson University provides an excellent review of Poa annua management strategies. This webcast, as well as a Bermudagrass Disease Update, can easily be accessed and reviewed for free by going to https://gsportal.usga.org/webcast/default.aspx.