Winter Advisory! How Winterkill Affects Cool & Warm Season Turf

February 5, 2018

Predicting winterkill is a difficult task because there are a variety of ways it can cause damage to turf grass. No matter the region, winterkill has the ability to attack both cool and warm season grass! Although winterkill can affect both cool and warm season grasses, damage may not be the same. Throughout this article, turf managers will learn what to expect if winterkill happens in regions where as well as what they can do to help cultivate turf that can sustain the harsh conditions of cooler weather.

What is Winterkill?
Winterkill is an all-inclusive term that is used to describe the various causes of turf loss over the cool winter months. Winterkill can happen due to a combination of factors including: low temperature kill, ice sheets, desiccation, crown hydration, and snow mold.

WINTERKILL on Cool Season Grasses
Many factors contribute to winterkill in cool season grasses, some of which are beyond one’s control. Conversely, poor turf management practices can also lead to winterkill. For the most part, cool season grasses are well adapted to low temperatures (more so than warm season grasses) but are still susceptible to winterkill. Five common ways cool season turf grass can sustain winterkill injury or death are:

  1. Low Temperature Kill (freeze/ thaw damage)
  2. Ice Sheets
  3. Desiccation
  4. Crown hydration
  5. Disease

How to Avoid WINTERKILL on Cool Season Grasses
Identifying the ground conditions that make cool season turf more susceptible to winterkill can greatly assist in prevention. Ground conditions that are more likely to lead to winterkill are identified here and should be managed, monitored and maintained throughout the lawn care season: 

  • Areas that receive heavy traffic throughout winter
  • Close mowed turf
  • Exposed areas prone to desiccation
  • Grass species known to be more susceptible to snow mold (i.e. annual bluegrass and creeping bentgrass)
  • Immature seedlings that weren’t fully established in late fall (annual ryegrass, perennial ryegrass and tall fescue are especially susceptible)
  • Low spots with poor drainage
  • Shaded turf grass
  • Turf covered with ice sheets for 45 days or longer
  • Turf grass with an inadequate lawn care routine – malnourished, unbalanced pH, poorly mowed and under watered

WINTERKILL on Warm Season Grasses
Although warm season grasses are typically less exposed to extreme winter temperatures, they can still fall victim to the effects of winterkill. There are many factors that contribute to winterkill on warm season grasses, some of which are beyond our control (exp. weather conditions). Others can be avoided with proper turf management techniques. Some of the most common ways warm season turf grasses sustain winterkill injury are:

  1. Low Temperature Spikes
  2. Unseasonably warm temperatures followed by quick freezing temperatures (freeze/thaw cycle) in late winter-early spring.
  3. Sustained low temperatures
  4. Disease like snow mold or spring dead spot
  5. Turf grass with an inadequate lawn care routine – malnourished, unbalanced pH, poorly mowed and under watered

How to Avoid WINTERKILL on Warm Season Grasses
Just as with cool season turf, identifying the ground conditions that make warm season turf more susceptible to winterkill can greatly assist in prevention. Ground conditions that are more likely to lead to winterkill are identified here and should be managed, monitored and maintained throughout the lawn care season:

  • North facing slopes
  • Poorly drained areas
  • Heavily thatched turf
  • Heavily shaded areas
  • Areas planted with poorly adapted cultivars or turf grass species
  • Areas with deficient levels of Potassium(K)
  • Areas that receive heavy traffic throughout winter
  • Areas lacking snow cover to insulate soil during low temperatures

PRO TIP: It’s not uncommon for older cultivars (a plant variety selected for a certain area) of Bermuda grass to be more susceptible to winterkill.

Winterkill Prevention for Both Cool and Warm Season Grass Species
Whether you have warm season or cool season grass, foreseeing winterkill damage due to environmental changes is unpredictable prior to entering the winter months. Fortunately, there are still preventative actions you can take. To prevent winterkill you need to maintain a healthy, dense turf with a strong root system. This can be achieved with a regular lawn care routine including the application of  fertilizers and soil amendmentsproper mowing, and adequate watering. Additionally, aeration and thatch management will help. It is also beneficial to take the necessary steps to “winterize” your turf so that it can survive harsh winter conditions and get a healthy start in spring.

 

References:

https://www.sportsfieldmanagementmagazine.com/columns/turf-health/protect-turfgrass-winter-damage/

https://www.sportsfieldmanagementmagazine.com/maintenance/winter-weather-forecasting-field-management/

http://plantscience.psu.edu/research/centers/turf/extension/factsheets/cool-season

http://purdueturftips.blogspot.com/2014/03/cool-season-turf-winterkill-potential.html

https://www.clemson.edu/extension/hgic/hot_topics/2016/pdf/09%20preparing_managing_warm_season_grasses_during_the_offseason%202%20col.pdf

http://msue.anr.msu.edu/resources/winterkill-of-turfgrass

http://purdueturftips.blogspot.com/2014/03/warm-season-turf-winterkill-2014-what.html

https://www.extension.umn.edu/garden/yard-garden/lawns/snow-molds-in-lawns/

http://extension.uga.edu/publications/detail.html?number=C1012

http://purdueturftips.blogspot.com/2014/03/warm-season-turf-winterkill-2014-what.html

http://extension.uga.edu/publications/detail.html?number=C1012

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