Unfortunately, no one has a crystal ball that provides an accurate long-term forecast for the remainder of winter. January through March can be the make-or-break portion of the offseason when it comes to winter injury. While there may not be cause for concern at this time, it is never too early to have a plan in place should the weather shift abruptly. Winter injury on cool-season greens can be caused by ice encasement, desiccation or crown hydration, and putting greens with higher populations of Poa annua are more at risk.
If ice forms on your putting greens, it is important to begin tracking the duration of ice coverage to determine if and when action needs to be taken. At this point in the winter, if ice forms on predominantly creeping bentgrass putting greens there is very little risk of ice coverage extending long enough that turf injury or death would occur. However, if Poa annua populations are high enough and the forecast indicates the duration of encasement will extend 30 to 45 days or longer, some important discussions will need to take place – and there are risks whether ice is removed or not.
Choosing not to remove ice increases the risk of winter injury from encasement, but physical removal can also result in turf damage. Topdressing with black sand can help melt the ice, but some luck is needed with the weather to have favorable conditions that promote melting, and water must be able to drain from the putting greens so you will need to clear channels for runoff if snow is present around the greens. Physical removal, for example with an aerator, should be a last resort because of the potential for damage to occur.
Exposed turf creates a completely different concern for winter injury. Frigid conditions can result in damage and the severity increases with high winds. Ideally, putting greens have been prepared for winter by raising mowing heights and topdressing to insulate the crown. Covering greens, especially those in exposed locations, can help reduce the risk of injury and prevent desiccation, but it is important to have staff install and remove covers based on the weather forecast.
Crown hydration injury happens when temperatures warm, cells rehydrate, and then a rapid drop in temperature occurs that causes cells to freeze and rupture. Poa annua is more susceptible to crown hydration and it usually happens in late winter or early spring. Cutting channels in the turf or installing dry wells to promote surface drainage can help reduce the risk of crown hydration.
Winter weather in the central U.S. has been relatively benign so far, but there is extreme cold in the immediate forecast and who knows what may come in the weeks after that. Monitor the weather closely, plan for the worst and hope for the best. For support navigating various winter injury scenarios, reach out to your regional USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org