Bispyribac–sodium, Sulfosulfuron, and Interseeding Creeping Bentgrass for Long-term Control of Roughstalk Bluegrass

Abstract

<jats:p>Roughstalk bluegrass (<jats:italic>Poa trivialis</jats:italic> L.) contamination is problematic on golf course fairways from the Midwest to the mid-Atlantic regions of the United States. Bispyribac–sodium and sulfosulfuron have potential to selectively control roughstalk bluegrass. Our objectives were to determine the most effective herbicide treatments for short- and long-term roughstalk bluegrass control and to determine if interseeding with creeping bentgrass (<jats:italic>Agrostis stolonifera</jats:italic> L.) after herbicide treatments will improve long-term control of roughstalk bluegrass or conversion to creeping bentgrass. Plots were treated with bispyribac–sodium or sulfosulfuron and then half of each plot was interseeded with creeping bentgrass in early August, 2 weeks after the final herbicide application in 2006, 2007, and 2008 in Indiana. Roughstalk bluegrass cover reduction was highest when treated with bispyribac–sodium at 56 or 74 g·ha<jats:sup>−1</jats:sup> a.i. applied four times or sulfosulfuron at 27 g·ha<jats:sup>−1</jats:sup> a.i. applied three times. Interseeding with creeping bentgrass improved long-term roughstalk bluegrass control and quickened conversion to creeping bentgrass. Furthermore, bispyribac–sodium and sulfosulfuron appeared to be more effective in the first 2 years of the study when seasonal heat stress was greater, which appeared to improve long-term roughstalk bluegrass control and promoted creeping bentgrass establishment. Chemical names used: {2,6-bis[(4,6-dimethoxypyrimidin-2-yl)oxy] benzoic acid} (bispyribac–sodium), {1-[4,6-dimethoxypyrimidin-2-yl]-3-[2-ethanesulfonyl-imidazo(1,2-a)pyridine-3-yl) sulfonyl]urea} (sulfosulfuron).</jats:p>

Seasonal Changes in Morphology and Physiology of Roughstalk Bluegrass

“…1). Turf quality and percent cover averaged across harvest dates and years was highest for L93 followed by Laser and then Pulsar (Table 1), which was similar to that reported previously (Morton et al, 2009;Rutledge et al, 2010a). However, RBG cover never fell below 90% over the growing seasons of our study, which was less dramatic than those observed by Morton et al (2009), where cover of untreated Pulsar fell below 20% after intense summer stress while Laser maintained >90% cover (Morton, 2008).…”

“…Mean daily maximum temperatures in Morton et al (2009) in July were 29.3°C compared to 28.3 and 26.0°C in 2008 and 2009 of our study, respectively. Furthermore, signifi cant damage occurred in RBG in our previous studies (Rutledge et al, 2010a) with 20 or more days per growing season with maximum daily temperatures ≥30°C while highs reached ≥30°C on only 7 and 12 d during the growing seasons of 2008 and 2009, respectively ( Fig. 1).…”

Physiological Changes in Roughstalk Bluegrass Exposed to High Temperature

“…This difference in high temperature tolerance results in areas of stressed, dormant, or dead RBG throughout mixed stands of RBG and CBG during supra‐optimal temperatures, therefore relegating RBG to a weed in CBG fairways. Herbicides including bispyribac‐sodium and sulfosulfuron selectively control RBG in CBG (McCullough and Hart, 2006; Morton et al, 2009; Rutledge et al, 2010a). Control of RBG as well as injury to CBG from these herbicides is dependent on ambient temperature (Lycan and Hart, 2006; McCullough and Hart, 2006; Rutledge et al, 2010a).…”

“…Herbicides including bispyribac‐sodium and sulfosulfuron selectively control RBG in CBG (McCullough and Hart, 2006; Morton et al, 2009; Rutledge et al, 2010a). Control of RBG as well as injury to CBG from these herbicides is dependent on ambient temperature (Lycan and Hart, 2006; McCullough and Hart, 2006; Rutledge et al, 2010a). The relatedness of temperature to both decline and control of RBG makes understanding its physiology under high temperatures critical for maximizing control or improving management techniques.…”

“…Herbicides including bispyribac-sodium and sulfosulfuron selectively control RBG in CBG (McCullough and Hart, 2006;Morton et al, 2009;Rutledge et al, 2010a). Control of RBG as well as injury to CBG from these herbicides is dependent on ambient temperature (Lycan and Hart, 2006;McCullough and Hart, 2006;Rutledge et al, 2010a). The relatedness of temperature to both decline and control of RBG makes understanding its physiology under high temperatures critical for maximizing control or improving management techniques.High temperature stress in plants occurs when temperatures exceed the critical threshold at which photosynthesis begins to shut down (Paulsen, 1994;Karim et al, 1999) and antioxidant production ABSTRACT Roughstalk bluegrass (Poa trivialis L.) (RBG) is more heat sensitive than creeping bentgrass (Agrostis stolonifera L.) (CBG), but the physiological basis for this difference is poorly understood.…”