Reducing Ultradwarf Bermudagrass Putting Green Winter Injury with Covers and Wetting Agents.

As ultradwarf bermudagrass (Cynodon dactylon x C. traasvalensis) putting green use continues to move further north into the transition zone, there is increased risk of sustaining winter injury from desiccation and low temperature exposure. Although protective covers have been an essential practice for ensuring winter survival of ultradwarf greens, installation and removal of these covers to allow for golf when the weather is favorable is costly and labor intensive. Reducing the overall number of covering and uncovering events without sustaining a significant increase in turf injury can have a beneficial impact on the budget of a golf course. This research aims to define the predicted low temperature threshold when covering an ultradwarf green becomes necessary and also quantify the effects of a late season wetting agent application on winter survival. This study was conducted on a USGA-constructed green with replicated plots of Champion, Mini-Verde, and Tifeagle bermudagrass. Covering treatments were applied as strip plots at forecasted low temperature thresholds of -9.4, -7.8, -5.6 and -4.0 °C and are compared to an uncovered control. A single late season (mid-December) wetting agent application (Revolution) was applied as a split plot to each cultivar x cover treatment. Soil temperature under the various cover treatments was monitored at a depth of 2.5 cm and soil volumetric water content was recorded weekly for all plots using TDR. Digital image analysis and visual ratings were used to assess winter injury and spring greenup.