Annual Bluegrass (Poa annua) Control in Creeping Bentgrass Putting Greens with Amicarbazone and Paclobutrazol

Amicarbazone is a photosystem II–inhibiting herbicide recently registered for annual bluegrass control in established turf systems that include creeping bentgrass. However, research to date reveals potential issues with creeping bentgrass tolerance to amicarbazone. Currently, the plant-growth regulator paclobutrazol is widely adopted by turf managers for chemical annual bluegrass suppression in creeping bentgrass putting greens. Field experiments were conducted throughout North Carolina in the spring of 2010 and 2011 to assess treatment regimens that included amicarbazone (49, 65, or 92 g ai ha−1) and paclobutrazol (70, 140, or 280 g ai ha−1) applied alone, as tank-mixtures, or used in tandem, at varying rates and sequential timings for annual bluegrass control in creeping bentgrass putting greens. In general, regimens including both compounds provided greater annual bluegrass control and acceptable turfgrass tolerance compared with stand-alone applications of amicarbazone at 8 and 12 wk after initial treatment (WAIT). When comparing regimens that included amicarbazone at 49 or 65 g ha−1, creeping bentgrass tolerance was greater for the higher application rate applied less frequently. These results indicate amicarbazone usage on creeping bentgrass greens may be beneficially affected with the incorporation of paclobutrazol to treatment regimens because annual bluegrass control with the combination was equal to or greater than stand-alone amicarbazone applications, and creeping bentgrass tolerance was superior 8 and 12 WAIT. Nomenclature: Amicarbazone; paclobutrazol; annual bluegrass; Poa annua L.; creeping bentgrass; Agrostis stolonifera L. Amicarbazone es un herbicida inhibidor del fotosistema II que fue recientemente registrado para el control de Poa annua en sistemas de céspedes establecidos incluyendo Agrostis stolonifera. Sin embargo, la investigación hasta la fecha revela problemas potenciales con la tolerancia de A. stolonifera a amicarbazone. Actualmente, el regulador de crecimiento paclobutrazol es ampliamente adoptado por especialistas en céspedes para la supresión química de P. annua en putting greens de A. stolonifera. Experimentos de campo fueron realizados en North Carolina en la primavera de 2010 y 2011 para evaluar regímenes con tratamientos que incluyeron amicarbazone (49, 65, ó 92 g ai ha−1) y paclobutrazol (70, 140, ó 280 g ai ha−1), aplicados solos o en mezcla en tanque, o usados en tándem, a dosis variables y en aplicaciones secuenciale