POST herbicide dicamba, but the lethal rate depended on plant age. Postemergence applications of clopyralid resulted in less than 45% control of purslane at harvest of leafy greens ( Norsworthy and Smith, 2005 ), but clopyralid is no longer labeled for
safe and cost-effective weed management protocol for seashore dropseed establishment, characterization of herbicide tolerance is essential. In this study, the tolerance of seashore dropseed to applications of pre- and postemergence herbicides and table
. 2004 ; McElroy and Breeden 2007 ). In Georgia, Tennessee, and Texas, application of the postemergence broadleaf herbicides aminocyclopyrachlor or 2,4-D + dicamba + MCPP, at different rates at 0, 2, 4, or 6 weeks before seeding perennial ryegrass
herbicide, followed weeks later by cultivation and debris removal ( Frances et al. 2010 ). Wildflowers are often propagated by seed, so use of preemergence herbicides at seeding can reduce establishment and decrease stand density. The use of postemergence
Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] is a turfgrass species traditionally adapted to low-rainfall areas that may incur unacceptable weed encroachment when grown in higher rainfall areas such as Florida. An experiment was performed to evaluate the tolerance of two new buffalograss cultivars, `Oasis' and `Prairie', to postemergence herbicides commonly used for grass, broadleaf, and sedge weed control. Twenty to 40 days were required for each cultivar to recover from treatment with asulam, MSMA, and sethoxydim (2.24, 2.24, and 0.56 kg-ha-l, respectively). Other herbicides used for postemergence grass weed control (metsulfuron, quinclorac, and diclofop at 0.017, 0.56, and 1.12 kg·ha-1, respectively) did not cause unacceptable buffalograss injury. Herbicides used for postemergence broadleaf weed control, triclopyr, 2,4-D, sulfometuron, dicamba (0.56, 1.12, 0.017, and 0.56 kg·ha-1, respectively), and a three-way combination of 2,4-D + dicamba + mecoprop (1.2 + 0.54 + 0.13 kg·ha-1), caused 20 to 30 days of unacceptable or marginally acceptable turfgrass quality, while 20 days were required for `Prairie' buffalograss to recover from atrazine treatments. `Oasis' buffalograss did not fully recover from 2,4-D or 2,4-D + dicamba + mecoprop through 40 days after treatment. Herbicides used for postemergence sedge control, bentazon and imazaquin, caused slightly reduced, but acceptable, levels of turf quality in both cultivars throughout the experiment. Chemical names used: 6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine (atrazine); methyl[(4-aminophenyl)sulfonyl]carhamate (asulam); 3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide (bentazon); 3,6-dichloro-2-methoxybenzoic acid (dicamba); (±)-2-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid (diclofop); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin); (±)-2-(4-chloro-2-methylphenoxy)propanoic acid (mecoprop); 2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]benzoic acid (metsulfuron); monosodium salt of methylarsonic acid (MSMA); 2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one(sethoxydim); 2-[[[[(4,6-dimethylethyl-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoic acid (sulfometuron); [(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid (triclopyr); (2,4-dichlorophenoxyl)acetic acid (2,4-D); 3,7-dichloro-8-quinolinecarboxylic acid (quinclorac).
herbicide performance in the spring, and our literature search revealed no reports in the refereed literature concerning the influence of spring application timing on dandelion control with postemergence broadleaf herbicides currently used on turfgrass
effective pre- and postemergence herbicides labeled for roadside use need to be identified. The studies in this preliminary and regional report characterized the response of tropical fimbry to the preemergence herbicides, oryzalin and oxadiazon, and to the
Trials were conducted under controlled conditions to determine the tolerance of young papaya plants (15 cm tall) to postemergence herbicides. Herbicides used were paraquat (1.68 Kg ai/Ha), MSMA (2.24 Kg ai/Ha), 2,4-D (4.26 Kg ai/Ha), bromoxynil (0.28 Kg ai/Ha), cyanazine (1.12 Kg ai/Ha), dimethenamid (1.12 Kg ai/Ha), endothal (0.56 Kg ai/Ha), imazameth (0.067 Kg ai/Ha), imazethapyr (0.028 Kg ai/Ha) lactofen (0.12 Kg ai/Ha), oxyfluorfen (0.03 Kg ai/Ha), acifluorfen (0.28 Kg ai/Ha), atrazine (2.24 Kg ai/Ha), and bentazon (1.12 Kg ai/Ha) as well as the untreated control. Atrazine, bentazon, cyanazine, imazemeth, imazethapyr, and dimethenamid did not cause phytotoxicity at the rates used and were equal to the untreated control. Other herbicides caused severe injuries followed by total death at 10 days after treatment.
With the potential introduction of glyphosate-resistant kentucky bluegrass (GRKB) (Poa pratensis L.), postemergence herbicides must be identified for renovation from glyphosate-resistant stands or control escaped GRKB. Field experiments were conducted in Indiana, Maryland, New Jersey, and Virginia from July to September 2004 to investigate efficacy of postemergence herbicides for kentucky bluegrass control. Herbicides tested included clethodim at 0.28 kg·ha–1 (a.i.), fluazifop-p at 0.43 kg·ha–1 (a.i.), formasulfuron at 0.03 kg·ha–1 (a.i.), glufosinate at 1.12 kg·ha–1 (a.i.), glyphosate at 1.68 kg·ha–1 (a.i.), rimsulfuron at 0.03 kg·ha–1 (a.i.), sethoxydim at 0.53 kg·ha–1 (a.i.), and trifloxysulfuron at 0.03 kg·ha–1 (a.i.). One and two applications of each herbicide were applied to separate plots with the sequential applied 4 weeks after initial treatments (WAIT). Single applications of glyphosate completely controlled kentucky bluegrass 4 WAIT in Maryland, New Jersey, and Virginia. Glufosinate completely controlled kentucky bluegrass with one application in Maryland and New Jersey but single and sequential applications provided only 80% to 88% control in Indiana and Virginia. Foramsulfuron and rimsulfuron required sequential applications for complete kentucky bluegrass control 8 WAIT in New Jersey and Maryland but <82% control was obtained in Indiana and Virginia. Trifloxysulfuron controlled kentucky bluegrass 95% to 100% with single applications in Maryland, New Jersey, and Virginia. Single applications of clethodim, fluazifop, and sethoxydim provided minimal stand reductions but sequential applications controlled kentucky bluegrass 65% to 100%. Results suggest glufosinate and trifloxysulfuron have the greatest potential for controlling GRKB while other herbicides provided erratic control and require sequential applications.
Twelve ornamental grasses from the genera Calamagrostis, Cortaderia, Eragrostis, Erianthus, Miscanthus, Sorghastrum, Spartina, Panicum, and Pennisetum were evaluated for tolerance to the postemergence herbicides fenoxaprop-ethyl, fluazifop-P, and sethoxydim at 0.4 kg a.i./ha. Calamagrostis was uninjured by fenoxaprop-ethyl as measured by visual injury ratings, height, and foliage dry weight. Greenhouse studies evaluated the tolerance of three Calamagrostis cultivars to fenoxaprop-ethyl rates of 0.4 to 3.2 kg a.i./ha with no observed visual injury from any treatment. However, the expansion rate of the youngest Calamagrostis leaf was reduced linearly with increasing herbicide rates each day after application. The highest rate (3.2 kg a.i./ha) reduced the leaf expansion rate by 1 day and all other rates by 3 days after treatment. Leaf expansion rate differed between Calamagrostis cultivars at different times after herbicide treatment. Dry weight of Calamagrostis arundinacea `Karl Foerster' was reduced at 4 weeks after treatment but not at 10 weeks after treatment. Chemical names used: (±)-ethyl 2-[4-[(6-chloro-2-benzoxazolyl)oxy)phenoxy]propanoate (fenoxaprop-ethyl); (R)-2-[4-[[5-trifluoromethyl)-2-pyridinyl]oxy]phenoxy]propanoic acid (fluazifop-P); 2[1-(ethoxy imino)butyl]-5[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one (sethoxydim).