-season annual grasses such as crabgrass ( Digitaria spp.) species ( Moshier et al., 1976 ; Shearman et al., 1980 ). Siduron does not control annual broadleaf weeds and has little postemergence activity ( Vencill, 2002 ). Quinclorac can be used both pre- and
Annual grassy weeds often inhibit establishment of spring-seeded creeping bentgrass (Agrostis palustris Huds.) on golf courses. The objective of this experiment was to evaluate the safety of the annual grass herbicide quinclorac in spring-seeded creeping bentgrass in varying climatic regions of the United States. Experiments were initiated in Indiana, Iowa, and North Carolina in Spring 2000. Treatments included siduron at 6.72 kg·ha-1 a.i. applied immediately prior to planting (PRE), and quinclorac at 0.84 kg·ha-1 a.i. applied 7 days before seeding (DBS), PRE, and 14 or 28 days after emergence (DAE). Herbicides were applied to three creeping bentgrass cultivars at each location. Siduron reduced establishment of `Providence', `L93', and `Putter' creeping bentgrass in Indiana. Quinclorac applied PRE, 14 DAE, and 28 DAE caused short-term phytotoxicity, primarily in `Providence' in Indiana. Quinclorac applications did not significantly affect cover of `Providence', `L93', or `Putter' in Indiana or `L93', `Pennlinks', or `Penncross' in Iowa. All applications of quinclorac reduced cover of `L93', `Pennlinks', and `Penncross' in North Carolina. Though quinclorac applications resulted in no long-term damage when applied to creeping bentgrass seedlings in Indiana or Iowa, results from North Carolina indicate that caution should be exercised when using quinclorac on seedlings of creeping bentgrass. Chemical names used: 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac); 1-(2-methylcyclohexyl)-3-phenylurea (siduron).
herbicides for selective postemergence (POST) control of smooth crabgrass in bermudagrass include quinclorac and MSMA ( McCarty et al., 2005 ). Quinclorac is a quinolinecarboxylic acid herbicide that causes cyanide accumulation in susceptible grasses, leading
irrigation restrictions to reduce the likelihood of phytotoxic effects on nonfood crops. Quinclorac is labeled for postemergence weed control in rice ( Oryza sativa ) and in warm- and cool-season grasses, including tall fescue ( Festuca spp.), kentucky
control in lakes, ponds, and other water bodies ( Koschnick et al., 2006 ; Michel et al., 2004 ). Thus, the need for additional effective aquatic herbicides is great. The herbicides tested in these experiments—bispyribac-sodium, quinclorac, topramezone
Siduron and quinclorac provide limited broadleaf weed control during seeded establishment of tall fescue. Carfentrazone and bromoxynil are contact herbicides that act primarily on broadleaf, dicot species. Research was conducted to evaluate tall fescue tolerance to carfentrazone or bromoxynil when integrated into traditional siduron and quinclorac weed control programs. Quinclorac at 0.84 kg·ha–1 applied at seeding followed by quinclorac at 0.84 kg·ha–1 35 days after emergence (DAE) and quinclorac at 1.68 kg·ha–1 plus carfentrazone at 0.034 kg·ha–1 applied DAE were the most injurious to tall fescue 42 and 49 DAE. While quinclorac sequential applications reduced turfgrass groundcover 42 DAE, tall fescue recovered by 49 DAE. Injury from all quinclorac treatments persisted until 63 DAE. Bromoxynil (0.28 or 0.56 kg·ha–1) or carfentrazone (0.017 or 0.034 kg·ha–1) caused minimal injury and no decrease in turfgrass groundcover when applied 35 DAE. While siduron applied at seeding followed by (fb) bromoxynil applied 35 DAE (6.7 fb 0.56 kg·ha–1) caused minimal tall fescue injury, a decrease in groundcover was observed at 49 DAE. No tall fescue cover reduction was observed for any treatment by 63 DAE. These data indicate that bromoxynil and carfentrazone can be safely used during seeded establishment of tall fescue beginning 35 DAE with no long-term effects on turfgrass stand development.
both experiments, five different rates of glyphosate (Roundup Weathermax; Monsanto Company, St. Louis, MO), dicamba (Clarity; BASF Corp., Durham, NC), clopyralid (Stinger; Dow AgroSciences, Indianapolis, IN), quinclorac (Facet L and Facet 75 DF, BASF
Smooth crabgrass [Digitaria ischaemum (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 (Agrostis stolonifera 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 (Lolium perenne 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-1) or chelated iron (Fe)+nitrogen (N) (FeSO4 at 1.1 kg·ha-1+N at 2.2 kg·ha-1) 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-1) 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-1) 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).
Three field experiments were conducted to determine if several preemergence and postemergence herbicides were safe to apply to creeping bentgrass (Agrostis stolonifera L. `Penncross') maintained at putting green height. When dithiopyr was applied at preemergence in late February or early March, the emulsifiable concentrate formulation (≤1.7 kg·ha-1) and granular formulation (≤1.1 kg·ha-1) did not reduce the quality or cover of creeping bentgrass. Applied at preemergence, bensulide plus oxadiazon at 6.7 + 1.7 kg·ha-1 and 13.4 + 3.4 kg·ha-1 reduced turfgrass quality for 2 to 3 weeks and 8 weeks after treatment, respectively. When MON 12051 and monosodium salt of methylarsonic acid (MSMA) (≤0.14 and ≤2.2 kg·ha-1, respectively) were applied at postemergence to creeping bentgrass in early June, the reduction in turfgrass quality varied from slight to moderate for 1 to 2 weeks, but turfgrass fully recovered with no effect on turfgrass cover. Quinclorac applied at postemergence in early June at ≥0.6 kg·ha-1 severely reduced creeping bentgrass quality and cover for ≥8 weeks. Diclofop at 0.6 kg·ha-1 applied to creeping bentgrass in June, July, or August maintained consistently higher quality and cover ratings than when applied at ≥1.1 kg·ha-1. Diclofop applied at 0.6 kg·ha-1 in June and repeated at the same rate in July reduced quality of creeping bentgrass less than when applied at 1.1 kg·ha-1 at any date. Chemical names used: O,O-bis (1-methylethyl) S-{2-[(phenylsulfonyl)amino]ethyl} phosphorodithioate (bensulide); (±)-2-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid (diclofop); S,S-dimethyl-2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate (dithiopyr); methyl-5-{[(4,6-dimethoxy-2-pyrimidinyl)amino] carbonylaminosulfonyl}-3-chloro-1-methyl-1-H-pyrazol-4-carboxylate (MON 12051); 3-[2,4-dicloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); 3,7-dicloro-8-quinolinecarboxylic acid (quinclorac).
Kikuyugrass (Pennisetum clandestinum Hochst.) an aggressive weed of cool season turfgrass in coastal California, Spreads rapidly by growth of robust stolons and seedlings. Kikuyugrass competition was studied by placing plugs of six turfgrasses in a kikuyugrass sward. Plug diameters increased when triclopyr (.56kg ai/ha) or quinclorac (.74kg ai/hg) were repeatedly applied (4 times) in combination with MSMA (2.2kg ai/ha). These herbicide combinations also eradicated kikuyugrass in lawns of cool season turfgrass. Kikuyugrass density was reduced from 75% of the turfgrass sward to 0%. Resurgence of kikuyugrass has not exceeded 5% 4 months posttreatment.