Date of Graduation

5-2018

Document Type

Thesis

Degree Name

Master of Science in Horticulture (MS)

Degree Level

Graduate

Department

Horticulture

Advisor/Mentor

Richardson, Michael D.

Committee Member

Karcher, Douglas E.

Second Committee Member

Brye, Kristofor R.

Keywords

Bermudagrass; Golf; Putting Green; Turfgrass

Abstract

As ultradwarf bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy) putting green use in the United States moves further north, there is risk of sustaining winter injury from low-temperature exposure and tissue desiccation. Protective covers reduce low-temperature exposure on ultradwarf bermudagrass greens. Desiccation of turf can be caused by hydrophobic soils. Wetting agents are applied to actively growing ultradwarf bermudagrass greens to relieve symptoms of hydrophobic soils. Less is known about the effects late-fall wetting agent applications on dormant bermudagrass putting greens. This research aims to define a predicted low-temperature threshold for covering ultradwarf bermudagrass greens and to quantify the effects of a late-fall wetting agent application on winter survival of ultradwarf bermudagrass. A protective cover and wetting agent trial was conducted on a sand-based putting green with plots of ‘Champion’, ‘MiniVerde’, and ‘TifEagle’ ultradwarf bermudagrass during the winters if 2015-2016 and 2016-2017. Cover treatments were placed at forecasted low-temperature thresholds of -9.4, -7.8, -5.6, and -4.0 °C and were compared to an uncovered control. A single late-fall wetting agent application was applied to each cultivar x cover treatment. An additional wetting agent trial was conducted by comparing a single application of various wetting agent treatments to an untreated control on a sand-based ultradwarf bermudagrass putting green. Spring green-up was monitored by quantifying green turfgrass coverage through digital image analysis. Soil volumetric water content was monitored at a depth of 3.8 cm using time-domain reflectometry. The wetting agent trial included two water drop penetration tests during each season. In both seasons, reducing the cover temperature threshold resulted in significant differences in green turfgrass coverage between treatments, but lower cover temperatures did not delay green-up of turf. ‘MiniVerde’ and ‘TifEagle’ greened up significantly faster compared to ‘Champion’. In 2016, wetting agent treatments greened up significantly faster than the untreated control. Multiple wetting agent treatments significantly reduced water drop penetration times in the top three cm of the soil profile. Our research demonstrates the potential to reduce the forecasted low-temperature for covering ultradwarf bermudagrass without negatively impacting turf health, potentially reducing golf course winter labor costs.

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