Evaluation of V-10029 and Trinexapac-Ethyl for Annual Bluegrass Seedhead Suppression and Growth Regulation of Five Cool-Season Turfgrass Species

Abstract

An experimental turfgrass growth regulator, V-10029, was compared with trinexapac-ethyl, a growth regulator used commonly on highly maintained turfgrasses, to evaluate growth suppression patterns and suppression of seedhead formation; the latter was evaluated on turfgrass species and annual bluegrass, a weedy species that appeared and developed seedheads in tall fescue. Plugs of creeping red fescue, Kentucky bluegrass, perennial ryegrass, and creeping bentgrass were taken from the field into a greenhouse. V-10029 at three rates (0.015, 0.029, and 0.059 kg/ha) was compared to an untreated control and trinexapac-ethyl at a label rate (0.382 kg/ha for perennial ryegrass and 0.287 kg/ha for the other four species). Of the eight replications for each treatment, four were not mowed for the purpose of evaluating suppression of seedhead formation, and four were used for weekly clipping collection to evaluate growth suppression. Compared to the untreated control, V-10029 at all three applied rates caused significant seedhead suppression in both tall fescue infested with annual bluegrass (> 90%) and perennial ryegrass (50 to 80%). Trinexapac-ethyl was not as effective, causing seedhead suppression levels of 57% in annual bluegrass found in tall fescue and 43% in perennial ryegrass. V-10029 caused unacceptable levels of discoloration (> 20%) in all turfgrass species, and discoloration increased with increasing rates of application. Patterns of growth suppression for tall fescue, Kentucky bluegrass, and perennial ryegrass, in response to V-10029 at all rates and to trinexapac-ethyl, were similar on a percent of suppression basis. Growth of creeping bentgrass was suppressed by V-10029 only at high rates. In contrast, creeping red fescue was significantly injured by V-10029 at all rates. The greatest growth suppression, in response for all treatments, occurred 2 to 3 wk after application. The effect of trinexapac-ethyl dissipated after 4 wk, while V-10029 was effective until 5 to 7 wk after treatment. Observed effects of V-10029 were consistent with its activity as an ALS-inhibiting herbicide and, therefore, as a Class D turfgrass growth regulator.

Características morfológicas de gramas em resposta à aplicação de trinexapac-ethyl

“…A aplicação de trinexapac-ethyl na dose de 0,287 kg ha -1 para a grama Poa pratensis e de 0,382 kg ha -1 para Lolium perene proporcionou reduções na emissão de inflorescência em ambas as espécies de 43 e 57%, respectivamente, tendo seus efeitos dissipados após quatro semanas da aplicação (Fagerness & Penner, 1998a).…”

Control of lodging and reduction in plant length in rice (Oryza sativa L.) with the treatment of Trinexapac-Ethyl and sowing density

“…Trinexapac-ethyl (TE) is a foliar absorbed cyclohexanedione plant growth regulator that can inhibit shoot growth in plants. It was registered as a plant growth inhibitor in 1998, and its particular potential in rice cultivation was noted (Fagerness and Penner 1998). In this study, we assessed the effect of sowing density and TE on lodging-related traits, plant height, and yield in 2 rice cultivars.…”

Seasonal Effects on Annual Bluegrass (Poa annua) Control in Creeping Bentgrass with Bispyribac-Sodium

“…and other weeds in rice (Oryza sativa L.) (Schmidt et al 1999;Webster et al 1999;Williams 1999). Previous research investigated bispyribac-sodium as a Class D growth regulator in five cool-season turfgrass species (Fagerness and Penner 1998). Field research with bispyribac-sodium has shown applications at 60 to 148 g ai/ha can reduce populations of annual bluegrass in a creeping bentgrass stand without significantly injuring the bentgrass (Lycan et al 2003;Park et al 2002).…”