By Trygve S. Aamlid, Wendy Waalen and Jørgen Hornslien, NIBIO
After two years with many cancelled meetings due to Covid-19, about 60 Norwegian superintendents, golf club managers and other industry people met at NIBIO Apelsvoll on May 19th to look at trials and hear the latest turfgrass winter stresses research.
The project ICE-BREAKER, funded by the Norwegian and Swedish Golf Federations, Scandinavian Turfgrass and Environment Research Foundation (STERF), the Research Council of Norway and four Norwegian Golf Clubs, was the focus of a blog post in April. In that article we mentioned our preliminary observations from 2021-22, i.e. that the unstable winter with little snow cover appeared to be taking its toll on many annual bluegrass greens Norway, Sweden and Finland this winter.
The major focus of the field day was field trials with various winter treatments on plots covered with annual bluegrass, creeping bentgrass or red fescue (blend of Chewings and slender creeping red fescue) on a push-up green at NIBIO Apelsvoll (61°N, 250 m a.s.l.).
- A (man-made) 10 cm ice cover from Dec. 2nd until natural ice melt around April 10th (about 130 days; treatment 1) resulted in total winterkill of all three species. Mechanical ice removal followed by spring covers from mid-March (treatment 6) made little difference except for slightly better survival of creeping bentgrass in one of the replications. Treatment 5, in which the plots were kept free of snow and ice for enhanced hardening until the ice layer was laid out on Jan 5th (97 days under ice), had better survival of creeping bentgrass and red fescue, but 97 vs 130 days of ice cover made little difference in annual bluegrass.
- The best treatment was the impermeable plastic sheet installed in treatment 4 on Nov. 28th. The plastic stayed on the green until April 19th (140 days) of which 135 days (from Dec. 2nd) had a 10 cm ice layer above the plastic. Under the plastic there was a spring tarp, but no ventilation pipes. In this treatment, creeping bentgrass and red fescue were both green and very attractive at cover removal (Figure 1) and there were no indications of anoxia or loss of color during the first days after removal (Figure 2). Annual bluegrass appeared to be slightly injured but recovered except for some spots where melting water most likely had been seeping in under the plastic from the wooden frame that surrounded the plot (Figure 3).
- Turf plots in the control treatment of ‘natural winter’ (Figure 2) and the treatment with clearing of snow thicker than 5 cm throughout the winter were both pale (yellow) at snow melt in April, but creeping bentgrass and red fescue, and to a lesser extent annual bluegrass recovered nicely during the following weeks. The similarity between these treatments is not surprising given the fact that maximum snow depth on the greens was only around 30 cm (Figure 2). From late January there was a natural ice layer under the snow in treatment 1, but the ice was rather porous and apparently had little impact on survival of creeping bentgrass and red fescue.
In conclusion, although the “natural winter” treatment came out quite nicely this winter, in the discussion after the presentation, many superintendents (Figure 4) argued that 2-3 weeks earlier opening in spring after use of plastic sheets is very important to most golf clubs. The average cost for covering an 18-hole golf course in Norway was estimated to about $13,000 USD, which may be regarded as an insurance premium to severe winter kill that may otherwise occur once or twice in ten years.