Smooth Crabgrass Control in Perennial Ryegrass and Creeping Bentgrass Tolerance to Quinclorac

Abstract

<jats:p>Smooth crabgrass [<jats:italic>Digitaria ischaemum</jats:italic> (Schreber) Schreber ex Muhlenb.] is an invasive weed of cool-season turfgrasses. Previous research has demonstrated that quinclorac is an effective postemergence herbicide for crabgrass control, but performance has been erratic in some regions. Furthermore, quinclorac may elicit objectionable levels of discoloration in creeping bentgrass (<jats:italic>Agrostis stolonifera</jats:italic> L.). The objectives of this 3-year field study were to determine optimum rates and timings of quinclorac applications that provide consistent levels of effective crabgrass control and to assess creeping bentgrass quality responses to quinclorac. To evaluate crabgrass control, quinclorac was applied in early-, mid- and late-postemergence timings at various rates to a perennial ryegrass (<jats:italic>Lolium perenne</jats:italic> L.) turf. Similar treatments were applied to creeping bentgrass to determine if application timing and rate influenced the level and duration of discoloration. Quinclorac was applied alone or was tank-mixed with either urea (N at 6.1 kg·ha<jats:sup>-1</jats:sup>) or chelated iron (Fe)+nitrogen (N) (FeSO<jats:sub>4</jats:sub> at 1.1 kg·ha<jats:sup>-1</jats:sup>+N at 2.2 kg·ha<jats:sup>-1</jats:sup>) to determine if they would mask discoloration. Crabgrass control generally was more effective in the early- and midpostemergence application timings. A single application of quinclorac (0.84 kg·ha<jats:sup>-1</jats:sup>) was effective where crabgrass levels were moderate, but sequential (i.e. multiple) applications were required where crabgrass levels were severe. The most consistent level of crabgrass control where weed pressure was severe occurred with three, sequential quinclorac (0.37 or 0.42 kg·ha<jats:sup>-1</jats:sup>) applications. Creeping bentgrass exhibited 2 to 11 weeks of unacceptable discoloration in response to sequential quinclorac applications. Chelated Fe+N was more effective than urea in masking discoloration. In general, chelated Fe+N tank-mixed with quinclorac masked discoloration and turf had quality equivalent to untreated bentgrass on most, but not all rating dates. Chemical names used: 3,7,-dichloro-8-quinolinecarboxylic acid (quinclorac).</jats:p>

Efficacy of Two Dithiopyr Formulations for Control of Smooth Crabgrass [Digitaria ischaemum (Schreb) Schreb. ex Muhl.] at Various Stages of Growth

“…This response was not observed in Tennessee. Site-to-site variability in quinclorac performance has been reported by other researchers (Dernoeden et al, 2003).…”

“…Similarly, Dernoeden (2001) observed efficacy with mid-postemergence applications (plants with more than three leaves but less than four tillers) of quinclorac in two years of a 3-year study; in the third year, efficacy with quinclorac was not commercially acceptable. In another 3-year study, Dernoeden et al (2003) observed variable control with mid-postemergence applications of quinclorac at 0.84 kgÁha -1 . The researchers suggested that poor performance observed on heavily infested sites might be the result of increased seed reservoirs in soil, rapid plant tillering, and dense mats of smooth crabgrass leaves protecting smaller plants in the canopy from contacting the spray solution.…”

“…Quinclorac is a quinolinecarboxylic acid herbicide that causes cyanide accumulation in susceptible grasses, leading to phytotoxicity, root and shoot growth inhibition, and eventual necrosis (Ferrell et al, 2003;Grossman, 1998;Koo et al, 1994;Senseman, 2007). Quinclorac has been shown to provide effective POST control of smooth crabgrass in various cool-and warm-season turfgrasses (Chism and Bingham, 1991;Dernoeden et al, 2003;Enache and Ilnicki, 1991;Hart et al, 2004;Johnson, 1994aJohnson, , 1994bJohnson, , 1995Johnson, , 1996Reicher et al, 1999); however, turfgrass injury after treatment with quinclorac has been reported to vary considerably. For example, Johnson (1997) reported as high as 65% centipedegrass [Eremochloa ophiuroides (Munro) Hack] injury after treatment with quinclorac at 0.84 kgÁha -1 .…”

Creeping Bentgrass Tolerance and Annual Bluegrass Control With Bispyribac-Sodium Tank-Mixed With Iron and Nitrogen

“…), also elicits chlorosis in CBG. The yellowing caused by quinclorac can be partially masked by tank‐mixing the herbicide with chelated iron and nitrogen (3).…”

Influence of Herbicide Safeners on Creeping Bentgrass (Agrostis stolonifera) Tolerance to Herbicides

“…Many herbicides, including amicarbazone, bispyribac-sodium; fenoxaprop-p-ethyl, topramezone, and quinclorac are registered on many cool-season turfgrasses, but their use is limited or prohibited on CBG because they cause unacceptable turfgrass injury (Anonymous 2004(Anonymous , 2012a(Anonymous , 2012b(Anonymous , 2013Brosnan and Breeden 2013;Dernoeden et al 2003;Hart et al 2004;Jefferies et al 2013;Johnson 1994;McCullough et al 2010;McDonald et al 2006;Park et al 2002;Reicher et al 2002). For example, fenoxaprop-p-ethyl is widely used to control crabgrass and goosegrass in cool-season turfgrass at 200 g ha À1 (Neal et al 1990).…”