By Dr. Chengyan Yue, Uma Parasuram, and Dr. Eric Watkins; University of Minnesota
Winter injury is a major threat to golf courses in cold climates. The extreme conditions of ice, snow, and freezing temperatures can wreak havoc on the delicate turfgrass surfaces that are the pride of any golf facility. But just how much damage are we talking about?
A comprehensive study conducted in 2022 surveyed superintendents from 96 golf courses in North America. Golf course superintendents in the sample have an average of 16 to 20 years of experience so experiences with winter stresses were not lacking.
From the courses we surveyed, on average, 10.4% of greens and 11.1% of fairways are damaged each year from winter injury (Figure 1). But in years with particularly harsh winter conditions, those numbers skyrocket to 19% of greens and 15.1% of fairways being lost or severely compromised. While the impacts to tees (7.2% average damage) and rough areas (6.5%) are slightly lower, they are still substantial. When severe winter injury strikes, up to 8.8% of tees and 8.2% of roughs have been affected.
So which grass types are the most vulnerable to winterkill? To dive deeper into this issue, we examined how superintendents thought different types of winter injuries were affecting various grass types. Figure 2 provides valuable insights into the vulnerability of different grass types to ice encasement, a common winter injury. According to the data, annual bluegrass (Poa annua) is highly susceptible, with 46% of respondents reporting its susceptibility. This finding aligns with previous research by Beard (1964) who demonstrated that annual bluegrass is the most susceptible grass type to ice encasement injury, while creeping bentgrass is the most tolerant. Interestingly, the graph shows that creeping bentgrass (Agrostis stolonifera) was the second most affected grass type, with 20% of respondents reporting its susceptibility to ice encasement. This contrasts with Valverde's (2007) controlled experiment, which found that creeping bentgrass suffered no injury under various winter scenarios, including ice encasement, while annual bluegrass incurred injury within 15 days of ice encasement.
The graph also reveals that perennial ryegrass (Lolium perenne) was moderately affected, with 15% of respondents reporting its susceptibility to ice encasement. The least affected grass types were Kentucky bluegrass (Poa pratensis) at 8%, fine fescue (Festuca spp.) at 6% and tall fescue (Schedonorus arundinaceus) at 5%. These findings highlight the importance of carefully selecting grass types based on their tolerance to winter injuries, particularly ice encasement, to ensure the long-term health and resilience of turf grass in regions prone to severe winter conditions.
This is just a subset of our findings. Our overall results underscored the importance of managing grass types strategically to minimize winter injury and highlight the need for proactive measures and tailored management practices to mitigate the impacts of winter injury on golf course turfgrass surfaces. Our survey did have some limitations; for example, superintendents who answered our requests to take the survey likely are those who have had to deal with severe winter injury. Therefore, we are likely showing a higher percentage of the golf course as affected by winter stresses than is reality. Nevertheless, for those courses where winter injury is a problem, it is of critical importance, leading to significant costs that can negatively affect the bottom line of the golf courses and the careers of the superintendents who manage them.
References
Beard, J. B. (1964). Effects of Ice, Snow and Water Covers on Kentucky Bluegrass, Annual Bluegrass and Creeping Bentgrass. Crop Science, 4(6), cropsci1964.0011183X000400060026x.
Valverde, F. J. (2007). Field evaluation of winterkill in annual bluegrass (Poa annua L.) and creeping bentgrass (Agrostis stolonifera L.) (p. 7051552) [Doctor of Philosophy, Iowa State University, Digital Repository].