Effect of trinexapac-ethyl overuse on the growth of Paspalum vaginatum

Trinexapac-ethyl (TE) inhibits vertical growth of turf, thereby reducing mowing frequency. Recently, TE has been widely used on turf at golf courses; however, it is often overused, leading to damaged turf. A field experiment was conducted on Paspalum vaginatum turf with 3 kinds of TE products (P, M, N) at 4 different concentrations, including a conventional concentration (1 mL·L-1), a medium-high concentration (1.5 mL·L-1), a very-high concentration (2 mL·L-1) and a super-high concentration (10 mL·L-1). Turfgrass clippings, biomass, color, density, and growth rate were measured during the experiment to examine the effects of TE overuse on P. vaginatum with the aim of providing a reference for the rational use of TE. Clippings taken from turf that were treated with the applications of the 3 products (P, M, and N) at the conventional concentration decreased by 70%, 78.5%, and 80%, respectively, and vertical growth rate decreased by 66.0%, 51.5%, 53.6%, respectively, when compared to the control. Clippings taken from the super-high concentration of P, M, and N decreased by 82.2%, 87.8%, and 81.3%, respectively, and vertical growth rate decreased by 71.1%, 72.2%, and 83.6%, respectively, when compared to the control. The higher the concentration of TE, the more the clippings and growth rate decreased. However, there was no significant difference between concentration treatments (P>0.05), i.e., concentration had no significant effect on biomass. The color of turfgrass exposed to the conventional concentration of P, M, and N was 7.9, 7.9, and 8.0, respectively, whereas the color of turfgrass exposed to the super-high concentration was 7.3, 7.2, and 7.2, respectively. The density of turfgrass when exposed to the conventional concentration of P, M, N was 8.1, 8.1, and 8.2, respectively, whereas the density of turfgrass exposed to the super-high concentration was 7.5, 7.4, and 7.4, respectively. A comprehensive analysis showed that at the conventional concentration of 1 mL·L-1, product P inhibited turf growth rate the most but had less influence on turf clippings, color, and density; thus, it had the best control effect. TE overuse did not have an obvious inhibition effect on turf but the quality of the turf decreased.