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

Abstract

maximum growth inhibition at 2 to 5 wk after PGR applications, along with improvements in turfgrass qual-Research on the gibberellic acid (GA)-inhibiting plant-growth regity. Existing concerns in the golf course industry with ulator (PGR) trinexapac-ethyl (TE) regarding seasonal effects of single vs. multiple applications of this product on turfgrass quality and PGR applications in bermudagrass include turfgrass distissue production has not been reported. Research was conducted at coloration 1 to 2 wk after application and PIGE. Discol-North Carolina State University on 'Tifway' bermudagrass [Cynodon oration has been observed with applications of TE but dactylon (L.) Pers. ϫ Cynodon transvaalensis (Burtt-Davy)] to commay be counteracted by tank mixing TE with an Fe pare effects of different seasonal application patterns of TE. Applicasource (Johnson, 1997; Wiecko, 1997). The literature tions of TE were made to fully established Tifway bermudagrass at has not reported on either PIGE or how it may be either 0.107 or 0.071 kg a.i. ha Ϫ1 . Seasonal application patterns inaffected by the seasonal impact of multiple PGR applicluded an initial application, followed by zero, one, or two sequential cations. applications at 4-wk intervals. Plots were rated weekly for turfgrass Known warm-season turfgrass growth responses to quality and clippings were collected weekly for evaluation of tissue decreasing temperatures and reduced light levels in the production. Results demonstrated that one application of TE provided temporary growth inhibition of Tifway bermudagrass. This effect, as fall include cessation of new growth and net loss of expected, disappeared 4 wk after initial treatment (WAIT). Post-chlorophyll from leaf tissues. Research has been coninhibition growth enhancement (PIGE) was observed from 6 to 10 ducted to investigate how these effects may be delayed WAIT in areas treated with a single application of TE at 0.071 kg or counteracted, presumably to artificially extend the a.i. ha Ϫ1 . However, total seasonal tissue production following a single perceived growth period of these species. Exogenous application of TE was equal to untreated areas, suggesting limited additions of growth-regulating substances such as either overall effects of PIGE. Conversely, one or two sequential applicathe fungicide carboxin or the hormone GA have aided tions of TE provided prolonged growth inhibition; total seasonal tissue in the delay of bermudagrass dormancy symptoms (Diproduction was reduced by up to 40%. Overall quality of Tifway Paola et al., 1981; Dudeck and Peacock, 1985; Karnok bermudagrass was enhanced by multiple TE applications and per-

Effects of plant regulators on the growth and flowering of Saint Augustine grass plants

“…The smallest reductions resulted from prohexadione-calcium and bispyribac-sodium applied at the respective doses of 100 and 40 g ai ha -1 which were, respectively, of 49.6 and 38.9% at 119 DAA (Table 3). Fagerness and Yelverton (2000) All the plant growth inhibitors used in this study were verified to bring about significant reductions in inflorescence height at 119 DAA in comparison with the plants of the check treatment. The lowest value resulted when trinexapac-ethyl was applied at the dose of 904 g ai ha -1 when the inflorescence height was of 2.9 cm.…”

“…It is important to emphasize that although the injury levels caused by trinexapac-ethyl at the doses of 113 and 226 g ai ha -1 , prohexadionecalcium at 100 and 200 g ai ha -1 , and by bispyribacsodium at 40 g ai ha -1 were statistically similar to those of the check treatment plants, they may be considered as unacceptable if lawns with good visual aspect are to be the objective (FAGERNESS; YELVERTON, 2000;McCARTY et al, 2004;McCULLOUGH et al, 2007).…”

Effect of plant regulators on growth and flowering of 'Meyer' zoysiagrass

“…ha -1 , Costa et al (2009) found reductions from 49.2 to 55.6%, respectively, in the production of dry mass of 'Meyer' zoysiagrass. Fagerness & Yelverton (2000) explained that a single application of trinexapac-ethyl at 107 g a.i. ha -1 caused a 40% reduction in the production of tissues in Tifway bermudagrass.…”

“…In contrast, high doses provide better results for longer periods, but with higher levels of injury. This imbalance between efficiency and injury can be solved with sequential applications involving welladjusted doses (Fagerness & Yelverton, 2000;Lickfeldt, et al, 2001, McCarty et al, 2004Waltz Jr. & Whitwell, 2005;Ervin & Zhang, 2007;McCullough et al, 2007).…”

Development of Different Grass Species with the Use of the Growth Regulator Trinexapac-Ethyl

“…of trinexapac-ethyl or higher was applied. Fagerness and Yelverton (2000) also found that, when the application of trinexapac-ethyl was carried out in a sequential manner, reductions in the dry biomass of the aerial part were approximately 40%.…”