Understanding stolon, rhizome growth characteristics of zoysiagrass in relationship to performance and establishment
Zoysiagrass (Zoysia spp.) is an important warm-season turfgrass species known to produce high turfgrass quality with lower inputs of water, nutrients and pesticides as compared to other warm-season turfgrasses. However, its use is not as widespread as some other turfgrasses primarily due to its slower rate of establishment and limited information on how to best grow-in and manage new hybrids. This knowledge gap leaves producers and consumers to determine best management practices based on their personal experiences instead of research, creating hesitation in the adoption of environmentally sustainable zoysiagrass cultivars.
A study was conducted at Texas A&M AgriLife Research and Extension Center at Dallas to evaluate the rate of establishment (from sprigs) and stolon versus rhizome density of four new and soon-to-be-released cultivars of zoysiagrass. Research plots were planted in the field in a randomized complete block design and replicated four times. Sprigging rates for each individual plot were one fourth of a “Texas bushel” (1.24 cubic feet/0.035 cubic meter) across a 35-square-foot (3.25-square-meter) plot area. Establishment data was taken during the first growing season on a weekly basis starting the week after planting by visual estimation of percent green coverage (PGC) as well as digital image analysis. During the second growing season, a single strip of sod was harvested from each plot at 12, 14 and 16 months after planting. Data on sod tensile strength, sod handling quality and thatch depth were collected at each harvest. Data of regrowth after harvest was collected via visual and digital PGC on a weekly basis starting the week after harvest. Stolon and rhizome density data was collected at each harvest by removing all leaf and root materials from a 4-inch (10.16-centimeter) plug sample, sorting rhizomes from stolons and measuring density with a WinRhizo scanner. Data collection and analysis are ongoing.
— Chase Martin (chase.martin@tamu.edu), Texas A&M AgriLife Research and Extension Center at Dallas
Response of hybrid bermudagrass sprigs to postemergence herbicides
Postemergence herbicides that control troublesome weeds during hybrid bermudagrass establishment via sprigs are limited due to potential turfgrass phytotoxicity and herbicide-resistant weeds. Research experiments were conducted in Blacksburg, Va., and Hope, Ark., in 2023 to evaluate the tolerance of Latitude 36, Tahoma 31 and TifTuf hybrid bermudagrass sprigs to postemergence herbicides applied four to five weeks after establishment. Thiencarbazone + foramsulfuron + halosulfuron did not injure bermudagrass > 6% across three cultivars and a total of seven site years. Topramezone + metribuzin injured turfgrass > 25% at two weeks after treatment, but tank mixing with thiencarbazone + foramsulfuron + halosulfuron reduced injury by 5% to 22%. Quinclorac injured hybrid bermudagrass 28% to 58%, depending on the cultivar, which was more than most other treatments.
Despite initial herbicide injury and reduction in turfgrass green cover, dark green color index and normalized difference vegetation index, sprigs recovered by four weeks after treatment. Injury on hybrid bermudagrass sprigs after herbicide treatments was negatively correlated with other response variables assessed during the study. Results suggest that topramezone or mesotrione mixed with metribuzin injures newly sprigged bermudagrass variably by cultivar and sometimes less than quinclorac, typically leading to equivalent or improved bermudagrass cover compared to industry standard herbicides. Mesotrione or topramezone mixed with metribuzin offers a new option to address problematic grassy weeds during bermudagrass sprig establishment.
— Navdeep Godara (ngodara@uark.edu), Daewon Koo, Ph.D., and Shawn D. Askew, Ph.D., Virginia Tech; and Hannah Smith, Ph.D., University of Arkansas
Darrell J. Pehr (dpehr@gcsaa.org) is GCM’s science editor.