ICE-BREAKER: Reducing the agronomic and economic impact of ice damage on golf courses and other grasslands


The project has six work-packages (WPs).

In WP1, a study examining anoxia tolerance (AT) was repeated in 2021/22. Samples were taken from SCANGREEN in December, vacuum-sealed, kept in darkness at 0.5°C and survival determined after 5-10 weeks. Species were ranked for AT in the order velvet bent (VB) > chewings fescue (CF) > colonial bent > slender creeping red fescue (SCRF) > creeping bent (CRB). Within species, the highest AT was found in VB ‘Nordlys’;  CF ‘Lykke’, ‘Compass II’ and ‘Radar’;  SCRF ‘Cezanne’ and ‘Charlotte’ and CRB ‘Penncross’.

In WP2, a trial examining ice encasement (IE), spring tarp + plastic cover between turf and ice, and timing of snow/ice removal on annual bluegrass (AB), CRB, and RF greens was repeated in 2021/22. Despite O2 levels down to 2%, there was less winter damage and the best spring start on CRB, AB and RF greens covered with plastic for up to 140 days.

WP3 includes large-scale trials on four GCs near Oslo.  Winter 2021/22 showed no need for ventilation, but higher temperature fluctuations at the green surface and increased risk of damage if the tarp under the plastic was omitted.

WP4 focuses on the critical transition when greens that have been under IE are exposed to ambient O2, strong light and low temperature after ice melt in spring. Trials at UMass and UMN showed that increasing duration of anoxia results in higher risk of photoinhibition upon re-exposure to 21% O2 and 800 µmol m-2 s-1.

WP5 addresses chemical inhibition of re-establishment from seed after IE. In 2021/22 uncovered greens of CB and RF with >7% OM in the thatch had 87% and 71% winter kill, respectively, after 128 days of IE. However, extracts collected just after ice melt showed no higher concentrations of butyric or acetic acid and no inhibition of germination or seedling growth compared with plots that had not been under IE. Thus the risk of inhibition of germination after IE of golf greens may have been exaggerated and temperature is the most important driver for recovery after reseeding.

WP6 compares the emergence of CRB cultivars after reseeding winter-killed greens in Sweden. While re-establishment in spring 2022 was slow due to low temperature, recovery rate tended to increase in the following order:  Independence (unprimed seed) < Independence (GA3-primed seed) < Luminary < Pure Select. NIBIO trials showed that apart from their temperature effect, temporary shade covers may have an effect in preventing light stress in newly emerged CRB seedlings.


Trygve S. Aamlid

Trygve S. Aamlid, NIBIO Department for Urban Greening and Vegetation Ecology, Turfgrass Research Group, Landvik, N-4886 Grimstad, Tel: + 47 90 52 83 78. E-mail:

Category: Overwintering
Status: Ongoing
Project period: 2020 - 2023

Fundings (kSEK)

  2020 2021 2022 2023 TOTAL
STERF 314 549 397 379 1639
Other sources 834 1195 1210 821 4060
Research Council of Norway 964 1666 1296 589 4515
TOTAL 2112 3410 2903 1789 10214

Project objectives

Primary objective

Improved understanding and improved strategies to prevent and repair damage caused by prolonged ice cover and melting water on golf courses and other grasslands.

Subgoals (corresponding to work-packages):

  1. Screen turfgrass cultivars for tolerance to anoxia, i.e. no O2 and and high CO2.
  2. Explore whether plastic covers or snow/ice removal during some or all of the winter can prevent ice and water damage in creeping bentgrass, red fescue and annual bluegrass or whether the grass will suffer from hypoxia.
  3. Evaluate whether sensors can be used to determine if ice layers should be crushed or if there is a need for ventilation under the plastic covers.
  4. Explore whether free oxygen radicals impair photosynthesis when newly seeded grass or grass that has been under ice is exposed to normal O2 levels at low temperature and high light intensity, and if such damage can be avoided by the use of shade covers in spring.
  5. Identify growth-inhibiting substances that can form on ice-covered greens and explore means to eliminate these before reseeding
  6. Evaluate cultivars of creeping bentgrass, tarps and biostimulants for faster re-establishment of greens killed by ice.