Snow cover is not necessarily a bad thing because it insulates the turf from cold temperature extremes and severe temperature fluctuations. Snow cover also protects turf from winter wind desiccation. In fact, snow coverage in and of itself is rarely a problem for turf because gas exchange between the soil and atmosphere is not completely restricted. Ice, on the other hand, if it persists for too long, is much more dangerous to turf health. If continuous ice coverage is a concern, the following actions should be considered as the final stretch of the winter season approaches.
- In areas of concern for potential damage, remove turf plugs and bring them inside to see if they green up when placed in a warm, sunny window or beneath a grow light. (For a great step-by-step video, please see Sampling Greens For Winterkill.)
- Begin checking beneath covers (if used) and ice layers for the presence of anaerobic conditions, which will have a distinctive sulfur odor indicating dying grass. If a smell is detected, make plans to break or remove ice or lift or vent beneath impermeable covers. With no smell, there is no problem at this point. (NOTE: This is usually not a concern for creeping bentgrass because it possesses excellent winter hardiness, but annual bluegrass greens may become vulnerable to damage once continuous snow/ice coverage reaches 40 days or more.)
- Initiate the process to remove ice if an anaerobic condition is detected at the surface of greens. There is always a risk associated with this action, but there are few options if anaerobic conditions are detected. If frigid temperatures are forecast in the near future, and they probably will be because winter is not yet over, use a permeable cover, straw or even blow snow back over the recently cleared surfaces to protect the exposed turf.
- As snow/ice thaws and during the winter transition to spring, it is important that surface water be able to drain from putting greens. If not, it will accumulate on putting surfaces and refreeze where turf will almost certainly be damaged from crown hydration injury. Whether or not snow is completely removed from putting greens, at the very least a channel for drainage purposes should be cleared.
- If impermeable covers are used, begin monitoring soil temperatures as snow cover is lost and the sun’s strength increases. Start the process of removing impermeable covers once temperatures beneath the covers reach the 41°F to 43°F range consistently. Plant hardiness declines rapidly at those temperatures. If available, use a permeable cover to protect the exposed turf while it re-acclimates to the new environment.
- Finally, keep an open channel of communication with golfers so they are aware of golf course conditions during the transition to spring. This has certainly been a difficult winter and winterkill injury is likely for several areas of the country.
It is important for golfers and course officials to know that winter injury is a very complex event because it is controlled by many variables that are not completely understood. The techniques and strategies used to protect turf throughout winter are improving, but are not, and probably never will be, perfect. Because weather conditions cannot be fully predicted or accounted for, there is always a chance that one can do everything right and yet still be wrong in that turf suffers winter injury. As such, the best that can be done is to try to identify the specific causes of injury and then address as many of those factors as possible with available management options. This reconfirms why it is a good idea to periodically pull turfgrass plugs throughout the winter for evaluation, especially when continuous ice coverage persists for 40 days or more or following weather events when the turf may have been hydrated and then subjected to very cold temperatures.