By Sam Bauer and Dr. Brian Horgan

The winter of 2016/17 was anything but normal and it feels like we’re getting used to saying that every spring.  An exceptionally warm November, over an inch of rainfall (and therefore ice) on Christmas, golf in mid-February, a general lack of snow cover, and temperatures more than 10 degrees below average in early-March are just a few of the ups and downs that we’ve experienced in the Twin Cities metro region this winter.  So, what does this mean for turf and golf courses, you might ask?

Ultimately, the best winter we could have for golf course turf would be a gradual cool down in the fall, which helps to harden off grasses for winter (a process known as acclimation), followed by good insulating snow cover on frozen soils, and a gradual warm up in the spring causing de-hardening (deacclimation) of our grasses.  This winter was anything but that. Initially, we were concerned about the early accumulation of ice on turf surfaces from the late- December rain, as extended periods of ice cover can cause suffocation and a toxic buildup of gases under impermeable ice sheets; annual bluegrass is reported to die in as little as 20-30 days under ice while bentgrass will survive for much longer.  Fortunately, the mid-February thaw

meant that a majority of the ice cover issues were behind us, but another challenge was looming. Annual bluegrass is known to initiate growth, or deacclimate, sooner in the spring than creeping bentgrass.  This has been reported by researchers at the University of Massachusetts in Dr. Michelle DaCosta’s program (see: http://usgatero.msu.edu/v13/n3-6.pdf).  The concern here, relates to a winter injury phenomenon known as crown hydration.  If annual bluegrass were to come out of dormancy during the warmup in February, it would take up water, and ultimately succumb to ice crystal formation in the crowns of plants causing most certain death.