Complementing Late‐Season Nitrogen Fertilization of Cool‐Season Turfgrass Putting Greens with Trinexapac‐ethyl

Abstract

Considering the vast number of golf course putting greens (PGs) comprised of creeping bentgrass (Agrostis stolonifera L.) and annual bluegrass (Poa annua L.) polystands; greater understanding of seasonal growth response to fall applications of growth regulators and/or N fertilizers is needed. The objective was to determine how timing of fall trinexapac-ethyl (TE; 4-[Cyclopropyla-hydroxymethylene]-3,5-dioxo-cyclohexanecarboxylic acid ethyl ester) plant growth regulator and/or N application rate influence(s) PG N assimilation, removal, and spring canopy density. Field studies were initiated on a mixed creeping bentgrass + annual bluegrass PG in September 2009 or 2010. Foliar applications of TE at 0, 0.044+0.044, or 0.088 kg ha -1 were made in combination with soluble N at 30 or 60 kg ha -1 . Treatment initiations, recurring every 10±1 d and centered on 15 October (30-yr average date of first frost), represent the four treatment timings. Fall N rate directly influenced PG density but did not interact with TE. Compared to the 30 kg ha -1 N rate, significantly lesser proportions of the 60 kg N rate were removed by mowing. Fall and early-spring PG growth decreased linearly with later N application dates, yet application timing significantly interacted with TE. Late fall TE treatment reduced early-spring shoot growth as much as 20%.

Perennial Ryegrass Wear Resistance and Soil Amendment by Ca- and Mg-Silicates

“…Likewise, Mehlich-3 extractable soil P (94 mg kg −1 ) resided within the optimal range for a mature turfgrass athletic field. Therefore, supplemental fertilization practices were limited to monthly applications of various urea fertilizers to ensure plant-availability of 10 to 20 kg N ha -1 per growing month of the two-year study [31]. Monthly scouting of disease and/or nutrient deficiency symptoms were assessed and recorded throughout the 2011 and 2012 growing seasons.…”

Reduced creeping bentgrass fairway reflectance following synthetic colorant application

“…Furthermore, said measures generate continuous, Abbreviations: CPC, Cu II phthalocyanine colorant; DAIT, d after initial treatment; DGCI, dark green color index; DSLT, d since last treatment; NDVI, normalized differential vegetative index; PDSO, petroleum derived spray oil; UAN, urea ammonium nitrate. ratio data readily complemented by current geographic information system platforms and emerging automated sampling technologies (Rogan & Schlossberg, 2013;Zhang et al, 2019). Similarly, cautionary reports pertaining to multispectral radiometric inference into turfgrass canopy characteristics have materialized.…”

“…Justifications for adoption include rapid and repeatable measures of canopy reflectance by any number of operators. Furthermore, said measures generate continuous, ratio data readily complemented by current geographic information system platforms and emerging automated sampling technologies (Rogan & Schlossberg, 2013; Zhang et al., 2019). Similarly, cautionary reports pertaining to multispectral radiometric inference into turfgrass canopy characteristics have materialized.…”

Plant growth regulator effects on winter hardiness of annual bluegrass putting green turf

“…Although research efforts have generally centered on the effects of GA‐inhibitor PGRs on reductions in clipping yield and increases in turfgrass quality and uniformity during the summer growing season, there is evidence for additional benefits of these PGRs in relation to winter and spring turf growth and persistence. For example, the late‐season application of trinexapac‐ethyl (TE; 4‐[Cyclopropyl‐a‐hydroxymethylene]‐3,5‐dioxo‐cyclohexanecarboxylic acid ethyl ester) was shown to reduce early‐spring shoot growth (approximately 10–20%) on a mixed annual bluegrass and creeping bentgrass putting (Rogan & Schlossberg, 2013), suggesting the potential for maintenance of chemical suppression throughout winter months. Fall application of TE was also previously reported to impact winter survival of annual bluegrass fairway turf, but this response varied depending on the autumn timing and application rate (Rossi & Buelow, 1997).…”