Major concerns for the use of velvet bentgrass (VB) in Scandinavia are whether current cultivars have sufficient winter hardiness, and whether it is possible to control the rapid formation of thatch in this species. The results from the four sub-projects are as follows:
1) As tested under controlled environments, freezing tolerance and resistance to pink snow mould (Microdochium nivale) did not vary among VB cultivars. Similar freezing tolerance in VB and creeping bentgrass (CB) was associated with similar levels of sucrose in crown tissue of acclimated plants. VB was more susceptible to M. nivale and showed
lower crown fructan content than CB. In darkness at 0.5 - 1.0 oC, even acclimated plants of VB and CB were not able to completely withstand snow mould invasion in the presence of simulated snow cover. Simulated ice cover for 12 weeks caused the greatest damage (only 9% survival) regardless of acclimation and inoculation with M. nivale.The critical duration of ice cover for plant survival was between 42 and 84 days.
2) Percentage of organic matter (OM) in the mat layer increased with increasing N under light topdressing, but not under heavy. Vertical cutting reduced OM from 6.4 to 5.3% at Landvik and resulted in generally better visual quality. Spiking led to softening of the green surface, but improved infiltration by more than 50%. We concluded that VB requires at least 150 kg N ha-1 yr-1 until the green is mature (1-2 years after sowing), after which the N rate should be considerably reduced. Topdressing with 1.0 mm sand every second week is recommended irrespective of green age. Mechanical treatments on mature VB greens may include grooming once a week, monthly vertical cutting, and spiking once or twice a year.
3) Neither rootzone composition nor irrigation regime affected mat thickness or OM %. Light and frequent irrigation provided relatively better overall impression of young VB compared with deep and infrequent irrigation, but the visual quality on straight sand plots was significantly decreased in response to light and frequent irrigation by the end of the study. Green Mix (sand+20% v/v garden compost) showed clear advantages in the form of higher visual quality, less pink snow mould, longer irrigation intervals and less risk for development of soil water repellency.
4) Practical evaluation / large-scale demonstration trials with VB were carried out on 10 golf courses in Denmark Finland, Sweden and Norway from 2007 to 2010.Greenkeepers met regularly at reference group meetings and at the velvet bentgrass workshop ‘Best management practice for velvet bentgrass putting greens’ in June 2010. The project is now finished. Five scientific papers and a doctoral thesis are almost ready for submission. By July 2011, at least four popular articles will also be published in Scandinavian turfgrass magazines.
The project is a collaborative effort by Bioforsk, UMB, Rutgers and Cornell Universities, USA, and University of Guelph, Canada. In addition to the grant from STERF, funding has been provided by Bioforsk and The Norwegian Research Council to cover the expenses of a graduate student taking a Ph.D. as part of this project. The graduate student will receive part of his/her training in USA and Canada.
Norwegian Institute for Bioeconomy (NIBIO), Department for Urban Greening and Environmental Technology, Turfgrass Research Group, Landvik, Reddalsveien 215, 4886 Grimstad, Norway.