Tyler Cooper

Methiozolin efficacy for annual bluegrass (Poa annua) control on sand- and soil-based creeping bentgrass putting greens.

Abstract Methiozolin is a new isoxazoline herbicide being investigated for selective POST annual bluegrass control in creeping bentgrass putting greens. Glasshouse and field research was conducted from 2010 to 2012 in Tennessee and Texas to evaluate annual bluegrass control efficacy with methiozolin. Application placement experiments in the glasshouse illustrated that root absorption was required for POST annual bluegrass control with methiozolin at 1,000 g ai ha−1. Soil-plus-foliar and soil-only applications of methiozolin reduced annual bluegrass biomass greater than treatments applied foliar-only. Field experiments evaluated annual bluegrass control efficacy with two application rates (500 and 1,000 g ha−1) and six application regimes (October, November, December, October followed by [fb] November, November fb December, and October fb November fb December) on sand- and soil-based putting greens. Annual bluegrass control with methiozolin at 1,000 g ha−1 on sand-based greens ranged from 70 to 72% compared to 87 to 89% on soil-based greens. Treatment at 500 g ha−1 controlled annual bluegrass 57 to 64% on sand-based greens compared to 72 to 80% on soil-based greens. Most sequential methiozolin application regimes controlled annual bluegrass more than single applications. On sand-based greens, sequential application programs controlled annual bluegrass 70 to 79% compared to 85 to 92% on soil-based greens. Responses indicate that methiozolin is a root-absorbed herbicide with efficacy for selective control of annual bluegrass in both sand- and soil-based creeping bentgrass putting greens. Nomenclature: Methiozolin [5-(2,6-difluorobenzyl) oxymethyl-5-methyl-3-(3methylthiophen-2-yl)-1,2-isoxazoline]; annual bluegrass, Poa annua L.; creeping bentgrass, Agrostis stolonifera L. Resumen Methiozolin es un herbicida isoxazoline nuevo que está siendo investigado para el control selectivo POST de Poa annua en “putting greens” del césped Agrostis stolonifera. Se realizaron investigaciones de invernadero y de campo desde 2010 a 2012, en Tennessee y Texas, para evaluar la eficacia de methiozolin en el control de P. annua. En el invernadero, experimentos de localización de la aplicación ilustraron que la absorción por la raíz fue requerida para el control POST de P. annua con methiozolin a 1,000 g ai ha−1. Aplicaciones de methiozolin al suelo y al follaje o solamente al suelo redujeron la biomasa de P. annua más que los tratamientos con aplicaciones solamente foliares. Los experimentos de campo evaluaron la eficacia en el control de P. annua con dos dosis de aplicación (500 y 1,000 g ha−1) y seis regímenes de aplicación (Octubre, Noviembre, Diciembre, Octubre seguido de (fb) Noviembre, Noviembre fb Diciembre, y Octubre fb Noviembre fb Diciembre) en putting greens en arena y en suelo. El control de P. annua con methiozolin a 1,000 g ha−1 en greens en arena varió entre 70 y 72% comparado con 87 a 89% en greens en suelo. Los tratamientos con 500 g ha−1 controlaron P. annua 57 a 64% en greens en arena, comparados con 72 a 80% en greens en suelo. La mayoría de los regímenes secuenciales de aplicación de methiozolin controlaron P. annua más que las aplicaciones individuales. En greens en arena, los programas de aplicaciones secuenciales controlaron P. annua 70 a 79% comparados con 85 a 92% en greens en suelo. Las respuestas indican que methiozolin es un herbicida absorbido por la raíz con eficacia para el control selectivo de P. annua en putting greens de A. stolonifera tanto en arena como en suelo.

Purple Nutsedge (Cyperus rotundus) Control in Bermudagrass Turf with Imazosulfuron

Abstract Purple nutsedge response to various rates and timings of imazosulfuron was evaluated in 2007 and 2008 in Abilene, TX. Bermudagrass phytotoxicity never exceeded 4% throughout the duration of the trial and all bermudagrass recovered within 7 d of herbicide application. Imazosulfuron (0.56 kg ai ha−1) followed by (fb) imazosulfuron 1 wk after initial treatment (WAIT), imazosulfuron at 1.12 kg ai ha−1, and trifloxysulfuron at 0.03 kg ai ha−1 exhibited 94 to 96% control 4 WAIT. Imazosulfuron (0.56 kg ai ha−1) fb imazosulfuron 2, 3, and 4 WAIT exhibited 99% control 4 WAIT. Eight weeks later (12 WAIT), imazosulfuron (0.56 kg ai ha−1) fb imazosulfuron 3 WAIT controlled purple nutsedge 91%, whereas similar control (82 to 84%) was observed with a single application of trifloxysulfuron and imazosulfuron (0.56 kg ai ha−1) fb imazosulfuron 2 and 4 WAIT. A single application of imazosulfuron at 1.12 kg ai ha−1 and sequential treatment with imazosulfuron (0.56 kg ai ha−1) on a 1-wk interval only controlled purple nutsedge 51 to 69% 12 WAIT. Timing of sequential imazosulfuron application was identified as an important component of the purple nutsedge control program. Waiting 2, 3, or 4 WAIT for sequential imazosulfuron applications, rather than 1 WAIT, increased purple nutsedge control 31 to 40% 12 WAIT. The highest level of purple nutsedge control (91%) was observed with applications of imazosulfuron (0.56 kg ai ha−1) fb imazosulfuron 3 WAIT applied during midsummer. However, control with this treatment was statistically similar to control with a single application of trifloxysulfuron (82%). Nomenclature: Imazosulfuron (2-chloro-N-[[4,6-dimethoxy-2-pyrimidinyl-amino]carbonyl]imidazo[1,2-a]pyridine-3-sulfonamide); trifloxysulfuron; common bermudagrass, Cynodon dactylon (L.) Pers. CYNDA; purple nutsedge, Cyperus rotundus L. CYPRO.

Control of Lesser Swinecress in Creeping Bentgrass Putting Greens

J. A. Hoyle, Postdoctoral Research Associate, C. M. Straw, Graduate Research Assistant, G. M. Henry, Associate Professor, Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602; T. Cooper, Graduate Research Assistant, L. L. Beck, Graduate Research Assistant, and A. J. Hephner, Graduate Research Assistant, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409