Tissue Production and Quality of ‘Tifway’ Bermudagrass as Affected by Seasonal Application Patterns of Trinexapac‐Ethyl

Abstract

Research on the gibberellic acid (GA)–inhibiting plant‐growth regulator (PGR) trinexapac‐ethyl (TE) regarding seasonal effects of single vs. multiple applications of this product on turfgrass quality and tissue production has not been reported. Research was conducted at North Carolina State University on ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. × Cynodon transvaalensis (Burtt‐Davy)] to compare effects of different seasonal application patterns of TE. Applications of TE were made to fully established Tifway bermudagrass at either 0.107 or 0.071 kg a.i. ha−1 Seasonal application patterns included an initial application, followed by zero, one, or two sequential applications at 4‐wk intervals. Plots were rated weekly for turfgrass quality and clippings were collected weekly for evaluation of tissue production. Results demonstrated that one application of TE provided temporary growth inhibition of Tifway bermudagrass. This effect, as expected, disappeared 4 wk after initial treatment (WAIT). Post‐inhibition growth enhancement (PIGE) was observed from 6 to 10 WAIT in areas treated with a single application of TE at 0.071 kg a.i. ha−1 However, total seasonal tissue production following a single application of TE was equal to untreated areas, suggesting limited overall effects of PIGE. Conversely, one or two sequential applications of TE provided prolonged growth inhibition; total seasonal tissue production was reduced by up to 40%. Overall quality of Tifway bermudagrass was enhanced by multiple TE applications and perceived fall dormancy was delayed. Results support the use of sequential applications of TE in Tifway bermudagrass for consistent growth management throughout the growing season, avoidance of PIGE, and improvement in visual turfgrass quality.