Winter Injury Fears January 8, 2014 By Darin S. Bevard

In spite of air temperatures at just 11°F, soil temperatures were hovering around the freezing mark at a two-inch depth. Fortunately, frigid temperatures were fairly short-lived lasting approximately 36 hours, which is reason for optimism when it comes to avoiding winterkill damage.

 Frigid temperatures have many people thinking about potential turfgrass injury when the grass emerges in the spring.

Earlier this week, a weather phenomenon dubbed a “polar vortex” provided the coldest temperatures to hit the Mid-Atlantic region in nearly 20 years. Low temperatures below zero in parts of the region and high temperatures in the single digits or low teens were widespread. Unfortunately, warm air ahead of the front melted snow cover that could have helped to buffer turf from this dramatic temperature change. Needless to say, this has resulted in more than a few questions to our office about potential impacts on the grass. It is too early to tell what the ultimate impact will be, but now is a good time to discuss some potential consequences.

The duration of the cold temperatures has a big impact on the potential for damage. This is the saving grace of the weather earlier this week. While temperatures were extremely cold, the duration of this weather was only about 36 hours. For direct low temperature kill, soil temperatures are generally more important than air temperatures because the crown, or growing point, of the plant is often at soil level. The soil can buffer rapid temperature change for short periods of time. This is good news for turfgrass regardless whether you are managing bermudagrass or other temperature-sensitive grasses such as perennial ryegrass and Poa annua.

Saturated soil conditions are a concern, but again, warmer temperatures forecasted for this weekend into next week mean that ice encasement will be short lived where it occurs, and maintenance crews will have the opportunity to carefully squeegee any standing water that remains, especially on putting greens.

Crown hydration injury has also been a big topic of discussion. This is most prominent in Poa annua. Crown hydration injury occurs when temperatures warm and plant cells begin to rehydrate with water. If this is followed by a rapid drop in temperature, ice crystals can form in the crown of the plant ultimately causing cells to rupture, potentially killing the plant. Think of accidentally leaving a soda in the freezer overnight and the subsequent mess that occurs when the can bursts open. This is similar to what happens with crown hydration injury. Fortunately, crown hydration injury generally occurs in late winter or early spring when much of the winter hardiness of the plant has been lost.

Given the lack of snow cover, the other potential concern is winter desiccation because cold temperatures and high winds basically freeze dry the leaves of the plant causing injury and potential death. Desiccation injury can be mitigated greatly with covers as they serve to reduce moisture loss from the turfgrass leaves.

The impacts of this cold spell will not be known until spring when turf greens up. With the short duration of the frigid temperatures brought on by a polar vortex, there is reason for optimism as it relates to this weather event. However, we still have a couple of months of winter left to go and many potential weather scenarios that can harm turfgrass can still occur. Discussing the potential impacts of winter weather with interested golfers and course officials as different weather events occur can prevent surprises come spring. Communication is very important. Hopefully, all will be well as the grass emerges from dormancy in March and April.


Source: Darin Bevard (

Information on the USGA’s Turf Advisory Service

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