Winterkill is an abiotic stressor of turfgrass species. This effect can be seen on any turf, but most especially on turfgrass that is mowed to lower heights such as bentgrass, annual bluegrass, and even bermudagrass. As Dr. Kevin Frank at Michigan State University has outlined in numerous publications, winterkill is anything abiotic that can harm your turf such as crown hydration, desiccation, and low-temperature kill.
Desiccation in the wintertime is the result of dry conditions, rather than wet. This effect is commonly seen year-round in areas prone to run-off, little rain or snow cover, or in arid climates. Turfgrass loses more water than it can take up, and appears to be dark brown as if it is still in dormancy. However, when a dry spell is expected, it is important to examine the level of desiccation. While tissues can be damaged, blade tissues are more regenerative than the crown where desiccation should not.
Crown hydration injury occurs when the weather is transitioning from winter into spring and a couple of days of warm weather are followed by a cold snap, or freeze. Grasses that break dormancy quicker, like annual bluegrass, take up ample water to aid in plant regulatory processes as the weather warms; a sudden freeze can come along and cause that water in the plant to crystalize, killing plant tissues. When water stays on the surface of the soil and doesn’t drain, ice can develop near the growing center, the crown, and kill the plant as well.
Low-temperature kill is similar to crown hydration, in that excess water taken up by the plant during warm temperatures may freeze when hit with an unexpected cold spell. In the fall as turfgrass growth slows down due to the cooling weather, that is typically the sign for the plant to begin acclimating to wintertime conditions. Turfgrass will begin the acclimation process by increasing the concentration of salts and nutrients within the cells to lower the overall freezing temperature of the plant. If winter comes on too quickly or freezing begins, this will come as a shock to the unprepared plant, ultimately killing it.
Always be sure to keep an eye on the damage winterkill can cause because it may look severe, but it is possible that the crown of the plant has survived and will persist. It is equally important to plant a cold-tolerant species of turf to reduce potential winterkill damage or overseed with a rapidly germinating cultivar.
Bertrand A., Castonguay, Y., Azaiez, A., and Dionne, J. (2013). Low-Temperature Stress. ASA-CSSA-SSSA Turfgrass Monograph, 279-318.
Frank, K. W., Bogle, E. N., Bryan, J. M., and Vargas Jr. J. M. (2017). Putting Green Reestablishment Following Winterkill. International Turfgrass Society Research Journal. 13(1): 250-255.
