Changes in Carbohydrate Status of Winter Overseeded Bermudagrass.

Bermudagrass (Cynodon dactylon L.) is the warm-season turf species of choice for golf course fairways, tees and athletic fields across much of the South and transition-zone regions because it tolerates close mowing and forms a durable, persistent turf. One of the major drawbacks to using bermudagrass is the straw-brown color during dormancy. To provide a green winter color and sometimes for playability, turf managers frequently overseed bermudagrass with cool-season species like ryegrass. Little information exists regarding the effects of winter overseeding on bermudagrass physiological health. This field study evaluated the effects of three perennial ryegrass (Lolium perenne L.) overseeding rates (0, 735, 1470 kg ha-1) on bermudagrass carbohydrate status and surface soil temperatures at four locations (Blacksburg, VA; Fayetteville, AR; Lexington, KY; and West Lafayette, IN). During the winter overseeding had a positive effect on the general appearance of the turf but also negatively affected bermudagrass spring density at some locations. Stolon tissue was analyzed for carbohydrate status during the 2014-2015 winter for all sites. At the West Lafayette site, total carbohydrates (TC) for ‘Patriot’ declined with time ranging from 73 to 34 mg g-1 tissue. The starch portion followed a similar temporal pattern of decline with values ranging from 36 to 28 mg g-1 tissue. A similar trend was observed for TC and starches during the 2015-2016 winter on ‘Riviera’ with values ranging from 350-115 and 128-53 mg g-1, respectively. Surface soil temperature effects from overseeding were somewhat variable with only slight increases (+0.5 ^oC) in the overseeded plots at the Lexington and Fayetteville sites. This study reaffirms the potential negative effects of overseeding on bermudagrass physiological health and the need for further investigations into cultural management practices that maximize overseeded bermudagrass health and winter survival.