Impacts of the Arctic Blast

In the January 12th Florida regional update, Todd Lowe discussed some of the effects of recent cold temperatures. Although low temperature records were not broken, the record for the length of time that below-average temperatures persisted was shattered. All the way down to Miami and the Florida Keys, daytime highs and nighttime lows stayed 20 to 30 degrees below average for two straight weeks. Though environmental conditions were not favorable for heavy frost to occur on a regular basis, this prolonged stretch of cold weather did cause extensive bermudagrass color loss, and the turf entered a semi-dormant stage throughout South Florida. This loss of color was a shock to many golfers. For those hearty souls who did go out and play, they experienced firm and fast conditions!

An additional benefit of the cold weather, no doubt overlooked by golfers but certainly not superintendents, is the severe burn-back of tropical signalgrass, which has become a major weed problem throughout the southern portion of the state.

At least for the courses in South Florida, the prolonged blast of cold weather caused only a temporary setback. With the return of milder and more normal temperatures, growth has resumed, and in turn, green-up has occurred on putting greens, tees, and fairways. Judicious nitrogen fertilization, in combination with micronutrients iron and manganese, further aided in promoting growth and the return of a green color more in keeping with everyone’s expectations. With the resumption of growth and routine mowing, cold-damaged leaves were removed. This, in itself, has helped reestablish a greener color.

With higher cut rough areas, the impact of the cold weather tends to be more pronounced, with the foliage damage increased. Naturally, roughs have been slower to respond, but, here too, after one or two mowings, the turf takes on a greener appearance. On the other side of the coin, with putting greens, the ultradwarf bermudagrass cultivars respond fairly quickly to warmer temperatures, but the downside is a slower putting speed. Thus, the employment of growth regulators has begun to occur.

For the northern third of Florida, freezing temperatures occurred for several nights in a row, and, as a result, bermudagrass and seashore paspalum went fully dormant and off-color. Most golfers in this part of the state are more understanding, as they witness this annually. But, with the large-acreage winter overseeding programs being discontinued at many courses, there have been concerns expressed about the brown grass. Temperatures have not sufficiently warmed enough to allow the bermudagrass to break winter dormancy. The resumption of sustained growth in North Florida cannot be expected for at least a couple of months, and the continuation of aggressive traffic management is essential to minimize damage and loss of turf coverage.

Only once in my 25-year career with the Green Section has true bermudagrass winter kill been encountered in Florida. That was in 1987 and was limited to a few putting greens in the Panhandle. In these cases, there was a direct correlation between the damaged areas and moderate to severe shade. However, this was before the introduction of the ultradwarf bermudagrasses and their widespread use. Not having previously experienced a similar prolonged stretch of cold temperatures with the ultradwarfs, there are definitely some concerns about the potential for low temperature injury, and even winter kill, on greens in the northern part of the state.

Oklahoma State University research determined that the relative low temperature tolerance of TifEagle, Mini-Verde, and Champion was 21.2, 21.6, and 23.4 degrees Fahrenheit, respectively. According to the Florida Automated Weather Network (FAWN), air temperature lows of 16 to 18 degrees Fahrenheit were recorded at various monitoring stations across the northern part of the state. Low soil temperatures of 33 to 39 degrees Fahrenheit also were recorded at these same stations. While visiting a couple of courses in Jacksonville recently, it was reported that over the January 9th weekend, putting green regionalUpdateContentzones were frozen solid, and it was impossible to change hole locations. During visits to these courses, the ultradwarf bermudagrass putting greens were found to still be in a semi- to fully-dormant stage, but based on examination of profile samples, no significant injury or winter kill of the stolons, rhizomes, or regionalUpdateContent system had occurred.

There are still concerns about the possibility of low temperature injury and winter kill at some northern Florida courses. The potential for problems is increased in locations with other stress factors, such as shade, excessive thatch, or restricted drainage. In locations where damage is suspected, harvesting plugs with a hole cutter, bringing the plugs indoors, planting them in pots, and putting the pots under a grow light, heat lamp, or in a south facing window, is suggested to assess if damage has occurred. The plugs should be adequately watered, and within 7 to 10 days a green-up response should begin to occur. If after two to three weeks the turf plugs are exhibiting 50% or less green foliage, significant cold damage will have occurred, and replanting probably will be required. Hopefully, this will not be the case, and with appropriate management practices during the late winter and spring, a full recovery can occur. It is recommended to keep everyone advised about the results of the damage assessment.

The Mid-Continent, Southeast and Florida Regions of the USGA Green Section have hosted Live Meeting webcasts to discuss and educate golf course superintendents, course officials and golfers about dealing with the winter freezing weather. Scheduled in a few weeks is a Live Meeting webcast that reviews cold temperature damage and recovery measures. Information can be found at http://gsportal.usga.org.

Source: John Foy, jfoy@usga.org or 772-546-2620.