Mowing frequency and performance of genetically modified St. Augustinegrass and standard commercial cultivars

Mowing is a key input when maintaining a turfgrass lawn but has an environmental impact and represents a repetitive expense. In an effort to reduce canopy growth rate and to improve weed control, genetically modified St. Augustinegrasses [Stenotaphrum secundatum (Walter) Kuntze] derived from the cultivar ‘Floratam’ are now in production and characterized by reduced levels of t gibberellic acid by insertion of the spinach (Spinacia oleracea L.) gibberellic acid 2-oxidase gene and glyphosate tolerance due to the insertion of 5-enolpyruvylshikimate-3-phosphate synthase gene from Arabidopsis thaliana (L.) Heynh. The objective of this study was to determine if eight genetically modified St. Augustinegrass entries required less frequent mowing than two standard commercial cultivars, Floratam and ‘615866’ (Seville™), while maintaining turfgrass quality (TQ) comparable to the standards. This study was planted in 2017 as a randomized complete block design at two Florida locations. Mowing frequency, TQ, density, and color were recorded from 2018 to 2019. Gray leaf spot severity was rated when present. Overall, the genetically modified St. Augustinegrass entries required less frequent mowing than standard cultivars, with PV-A and PV-B requiring less frequent mowing than Floratam across all seasons at both locations. Of these two, PV-A showed TQ comparable to Floratam at Fort Lauderdale Research and Education Center for the entirety of the trial, and at Plant Science Research and Education Unit for 7/10 seasons. For end-users, the availability of a high performing turfgrass with reduced mowing requirements can lead to a decreased maintenance cost and a reduced environmental impact.