In the previous regional update, John Foy reported that most areas throughout Florida have received above average rainfall in recent weeks and, in some cases, throughout the entire summer months. This trend has continued into the fall for most of South Florida. While it is nice to see a high water table maintained on golf course water bodies, the responses have not all been positive.
Simple maintenance tasks, like mowing, are difficult in rain, especially if there is the likelihood of lightning. Eventually, the ground becomes saturated and impossible to mow without causing unsightly tire ruts in low-lying areas. If these areas remain saturated for long periods, there is a greater potential of turf loss from lack of oxygen. For this very reason it is common on some golf courses to lose turf surrounding drain basins at this time of year, following periods of extended rainfall.
Weeds are particularly problematic pests in Florida due to the warm and humid subtropical environment that persists throughout the year. Weed seeds can quickly germinate at this time of year and become quite aggressive within a matter of weeks. Most herbicides require a “rain safe” period following application
so that the chemical can be adequately absorbed by the plant. Herbicide scheduling is a difficult task during periods of extended rainfall, as no golf course superintendent wants to apply a herbicide only to have it wasted as rainfall removes it from the leaf tissue shortly after application . Needless to say, weeds have been a common topic of concern on recent TAS visits, especially on golf facilities that do not have a designated spray technician.
The extended rainfall has not only created an inconvenience to daily maintenance, and a nuisance in regards to weed control, but it has had a more negative impact on closely mown surfaces. All plants require sunlight to produce their own food through photosynthesis. Turfgrass leaves possess the pigment chlorophyll, which converts solar radiation into energy. Closely mown surfaces like putting greens have an inherent disadvantage regarding photosynthesis because there is simply less leaf tissue. As a result, root depths on putting greens are generally significantly shallower than any other playing surface on the golf course. Extended rainfall brings with it an abundance of clouds that reduce sunlight penetration to the turfgrass canopy. Research shows that bermudagrass putting greens perform best when at least eight hours of full sunlight is received by the turf on a daily basis. It is not uncommon for some regions to receive only one or two hours of sunlight each day during rainy summer months. Closely mown putting greens can become quite thin at this time of year and succumb to disease pressure. Some bermudagrass “off-types” are particularly sensitive to reduced sunlight situations and have performed quite poorly in recent weeks.
It is important to guard against poor climatic conditions like reduced sunlight by incrementally raising mowing height at certain times of the year. With traditional fertility and surface management programs, raising the mowing height has resulted in significantly decreased putting speeds, and other cultural practices like increased rolling and double mowing are necessary to maintain acceptable playing conditions. However, an increasing number of golf courses in our region are utilizing innovative programs that reduce nitrogen fertilization, especially foliar nitrogen, and maintain improved speed and better overall turf health (see Changing Times in Ultradwarf Bermudagrass Putting Green Management).
Given the abundance of rainfall, it is not surprising that black layer has been observed on putting greens at several golf courses visited recently. Black layer is a condition in the soil caused by anaerobic bacteria that thrive when soils become saturated and depleted of oxygen. Black layer is produced from the hydrogen sulfide gas produced by the bacteria, which stains the adjacent soil and organic matter dark gray to black. Eventually, black layer may harm the turf, but initially it is a sure sign that soil is remaining saturated for a prolonged period and needs to be oxygenated. Supplemental venting with 0.25-inch solid tines is recommended on a regular basis to relieve compaction and increase oxygen exchange through the soil profile.
Hopefully, normal weather patterns will soon return, as October is generally one of the best months in our region for growing healthy turf. Courses that are currently struggling should improve considerably over the next six to eight weeks, just before the onslaught of peak season play begins!
Source: Todd Lowe, email@example.com or 941-828-2625