Photo Caption: Winterkill is a relative term where part of a grass plant or entire turfgrass stand dies during the winter. Firm internodes that are green, white, red or purple in color indicate bermudagrass stolons are alive. Soft, mushy internodes that are brown or straw tan in color suggest that the stolon is dead. (Photo courtesy of Dr. Dennis Martin, professor & turfgrass specialist, Oklahoma State University).
Warm-season grasses, better adapted to the South, will have a tough time surviving the arctic cold that has crept across the United States. However, improvements in bermudagrass varieties such as ‘Latitude 36’, ‘Northbridge’ and ‘Patriot’ should be up to the challenge. With financial support from the USGA, plant breeders at Oklahoma State University have specifically developed these varieties to survive periods of sub-freezing temperatures.
The cold-hardy bermudagrasses are ideal for use in parts of the eastern, western and southern United States for golf course fairways and tees, sports fields, commercial grounds and residential lawns, in part, because of its excellent traffic tolerance and recuperation rate once it is damaged.
Tested for seven years at Oklahoma State University before entering a national testing phase, Latitude 36 and Northbridge then underwent rigorous independent evaluation by researchers at land-grant universities across the southern and central transition zone of the United States. At the conclusion of the 2007-2012 National Turfgrass Evaluation Program (NTEP) bermudagrass trials, Latitude 36 claimed overall top honors, beating out many strong competitors.
Of particular importance is the performance for these grasses in sub-freezing, winter conditions. Percent winterkill data was collected at Oklahoma State University and Virginia Tech University (see Table 1) after the 2009-10 winter. During that winter, freezing temperatures were much below normal for the south and central U.S. (see Figure 1). The good news is that several bermudagrass varieties survived the arctic blast.
Figure 1 . Temperature anomalies for the 2009-10 winter.