February is a tricky month for golf course superintendents in northern areas. Many putting greens in the Northeast have gone in and out of dormancy several times, which means the turf is more vulnerable to damage at arguably the most lethal time of winter.
There are some important things to remember with winter injury. First and foremost, Poa annua is much more susceptible to damage compared to creeping bentgrass. Research has shown that Poa annua has a lower level of freezing tolerance and it will deharden – i.e., lose freezing tolerance – more readily than creeping bentgrass. A study at Olds College in Canada found that certain biotypes of Poa annua can lose freezing tolerance when subjected to temperatures of 45 degrees Fahrenheit for 48 hours (Tompkins et al., 1996). With many parts of the region experiencing temperatures near or above 45 degrees Fahrenheit recently, it’s safe to assume the turf isn’t as prepared for single-digit temperatures compared to earlier in winter.
Direct Low-Temperature Kill
Knowing that concerns exist for direct low-temperature kill, there is little that can be done at this point in winter to prevent damage. However, closely monitor temperatures on greens that occupy colder growing environments to document site-specific conditions. Also, bring turf samples inside a few times during the remainder of winter so you have a sense for what, if any, level of damage has occurred.
Crown Hydration Injury
Preventing crown hydration injury primarily comes down to reducing the potential for the turf to take up water and refreeze. Poa annua is more likely to take up water during a warm stretch of weather compared to creeping bentgrass, which is why it’s so susceptible to crown hydration. Removing snow or cutting drainage channels within the snow can be effective at minimizing water uptake and refreezing events, but there are plenty of examples where these actions have caused more damage than they prevented. Removing snow also requires ample labor, so it’s a hard decision to make and hard to execute. If a refreezing event seems imminent, superintendents have greatly reduced the potential for crown hydration by cutting sod channels or using dry wells to ensure water drains off putting greens. Give these temporary drainage solutions a try and you won’t regret it the next time you have melting snow or a rainfall event in late winter.
If you have questions or concerns about winter injury and prevention strategies, contact your regional USGA agronomist.
References
Tompkins, D.K., C.J. Bubar. J.B. Ross. 1996. Physiology of low-temperature injury with an emphasis on crown hydration in Poa annua L. and Agrostis palustris. 1996 PTRC Annual Report. pp. 40-49.
Northeast Region Agronomists:
Adam Moeller, director, Green Section Education – amoeller@usga.org
Darin Bevard, senior director, Championship Agronomy – dbevard@usga.org
Elliott L. Dowling, senior consulting agronomist – edowling@usga.org