Alternative covering approaches to protect ultradwarf bermudagrass putting greens from winterkill

Winterkill remains a constant concern for warm‐season putting greens in the transition zone, particularly on ultradwarf hybrid bermudagrass [ Cynodon dactylon (L.) Pers × C. transvaalensis Burtt‐Davy]. Using protective covers is an essential management strategy to prevent winterkill on putting greens. A practice has been suggested in which additional air space (commonly referred to as an air gap) beneath the cover might enhance turfgrass survival, but this has not been rigorously tested. The objective of this trial was to improve existing cover strategies by incorporating various air gaps beneath protective covers. A field trial was conducted from Fall 2019 to Spring 2020 and repeated from Fall 2020 to Spring 2021 in Fayetteville, AR, on a putting green with replicated plots of the ultradwarf bermudagrass cultivars ‘TifEagle’, ‘MiniVerde’, and ‘Champion’. Five cover treatments were applied in a strip‐plot design across all cultivars. Three air gap materials—straw, batting fabric, or drainage pipe—were placed beneath protective covers and compared with a cover‐alone treatment and an uncovered control. Soil temperature was continuously monitored at a depth of 1.0 inch throughout the trial, and spring green‐up was assessed using digital image analysis and visual quality ratings. The winter of 2019–2020 was mild, with minimal winterkill observed. In 2020–2021, all uncovered controls experienced widespread winterkill, regardless of cultivar. The straw and batting air gap treatments provided significantly warmer soil temperatures in both years of the trial but had minimal effects on spring green‐up or winter survival compared with covers alone. Because of the cost and labor involved in deploying and removing air gaps and covers, an air gap would not currently be recommended for widespread winter protection of bermudagrass greens.