Although we already knew it, the National Weather Service recently confirmed that record-breaking heat was experienced through the eastern two-thirds of the country during the summer of 2010. For Florida, this was the second hottest summer to occur since records have been kept. Bermudagrass and other warm season species such as seashore paspalum, do possess good heat tolerance. Yet, there are limits, and the hot temperatures of the summer have had an impact. This is especially the case with ultradwarf bermudagrass putting greens.
During TAS visits conducted over the past few weeks, very shallow and weak root system development has been a common finding. This, in turn mandates that very careful attention be given to soil moisture/irrigation management to avoid the rapid onset of drought stress. There have also been instances where the health and quality of bermudagrass fairway and rough areas have been impacted by heat and/or drought stress. The current 10- to 15-day forecast is predicting that temperatures will remain above average for Central and South Florida, and recovering from the stresses of the summer will still be difficult.
Along with weak and shallow roots, mower scalping damage on putting greens is another problem that is being encountered on a regular basis. In some cases, and because of mandated budget reductions, it has not been possible to keep up with core aeration and topdressing programs throughout the summer; this has resulted in excessive thatch/organic matter accumulation in the upper rootzone. Along with the persistence of a softer surface condition that results in increased mower scalping damage, moisture retention in the rootzone is increased and gas exchange is further reduced. These physical conditions further contribute to a shallow and weak root system. At this point it is not possible to reduce and control upper rootzone organic matter accumulation through core aeration. However, continuing with frequent and adequate topdressing for organic matter dilution can absolutely help in maintaining a firmer, drier, and smoother surface condition. Though cutting back on topdressing of bermudagrass putting greens will provide some cost savings, and if upper rootzone organic matter accumulation is not adequately managed, putting green performance will be compromised on the short and long term.
Also on a couple of recent TAS visits it was found that turf scalping damage was occurring because of the extremely low height of cut being maintained. In both of these cases, the putting green mowing units were being set at a bench height of cut of 0.120-inch. However, by using a prism gauge it was found that the actual effective height of cut was below 0.100-inch. It has long been known that there can be variations in bench settings versus effective heights of cut. With heights of cut routinely being maintained, the impact of a lower effective height of cut is magnified to a greater degree. Thus, besides avoiding mechanical damage, emphasize the need for adequate leaf surface area in late summer and fall, and support photosynthesis and carbohydrate production and storage.
If not already being practiced, superintendents and the equipment technicians should use a prism gauge to check the effective height of cut of the putting greens. It would again be reiterated that the continual practice of extremely low heights of cut is not the total answer for producing putting green conditioning, and, in particular, medium fast to fast putting speeds.
Although fall has officially arrived, Central and South Florida will continue to experience a summertime weather pattern for at least six to eight more weeks. Hopefully, there will be some moderation in temperatures and humidity so that the turf, as well as the staff, is not subjected to ongoing stress.
Source: John Foy, firstname.lastname@example.org or 772-546-2620.